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Title: Handbook of anæsthetics
Author: J. Stuart Ross
Contributor: Alexis Thomson
H. Torrance Thomson
Wm. Quarry Wood
Release date: April 29, 2025 [eBook #75985]
Language: English
Original publication: Edinburgh: E. & S. Livingstone, 1919
Credits: deaurider, Karin Spence and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)
*** START OF THE PROJECT GUTENBERG EBOOK HANDBOOK OF ANÆSTHETICS ***
HANDBOOK OF
ANÆSTHETICS
BY
J. STUART ROSS, M.B., CH.B., F.R.C.S.E.
LECTURER IN PRACTICAL ANÆSTHETICS, UNIVERSITY OF EDINBURGH;
HONORARY ANÆSTHETIST EDINBURGH DENTAL SCHOOL;
ANÆSTHETIST, DEACONESS HOSPITAL; INSTRUCTOR
IN ANÆSTHETICS, EDIN. ROYAL INFIRMARY
With an Introduction
BY
HY. ALEXIS THOMSON, C.M.G., M.D., F.R.C.S.E.
PROFESSOR OF SURGERY, UNIVERSITY OF EDINBURGH
AND CHAPTERS UPON
Local and Spinal Anæsthesia
BY
WM. QUARRY WOOD, M.D., F.R.C.S.E.
LATELY TEMPORARY ASSISTANT SURGEON, EDINBURGH ROYAL INFIRMARY
AND UPON
Intratracheal Anæsthesia
BY
H. TORRANCE THOMSON, M.D., F.R.C.S.E.
ANÆSTHETIST TO THE LEITH HOSPITAL
EDINBURGH
E. & S. LIVINGSTONE, 17 TEVIOT PLACE
1919
CONTENTS
CHAP. PAGE
INTRODUCTION BY PROFESSOR ALEXIS THOMSON ix
PREFACE xi
I. PHYSIOLOGICAL ACTION OF ANÆSTHETIC DRUGS 1
II. SHOCK AND ANÆSTHESIA 5
III. ASPHYXIA OR ANOXÆMIA 15
IV. METHODS OF ANÆSTHETISING 28
V. THE CLINICAL OBSERVATION OF THE PATIENT 31
VI. THE PREPARATION OF THE PATIENT 42
VII. NITROUS OXIDE 46
VIII. NITROUS OXIDE AND OXYGEN 60
IX. ETHER 74
X. INTRATRACHEAL ETHER 96
XI. CHLOROFORM 109
XII. ETHYL CHLORIDE 122
XIII. MIXTURES OF NITROUS OXIDE AND ETHYL CHLORIDE 128
XIV. MIXTURES OF CHLOROFORM AND ETHER 134
XV. SEQUENCES 137
XVI. THE ACCIDENTS OF ANÆSTHESIA 140
XVII. THE SEQUELÆ OF ANÆSTHESIA 151
XVIII. POSTURE OF THE PATIENT 157
XIX. THE CHOICE OF THE ANÆSTHETIC 162
XX. LOCAL ANÆSTHESIA 171
XXI. SPINAL ANÆSTHESIA 193
APPENDIX 201
INDEX 209
LIST OF ILLUSTRATIONS.
FIG. PAGE.
1. Shock (Grey and Parsons) 6
2. Shock (after Crile) 8
3. Diagram to Illustrate Anoci-Association (after Crile) 11
4. Apparatus for Lane’s Saline Infusion 13
5. Diagram of the Vicious Circle of Asphyxia 20
6. Hewitt’s Mouth Props 22
7. Bellamy Gardner’s Mouth Props 23
8. Phillips’ Modification of Hewitt’s Artificial Air-way 23
9. Silk’s Nasal Tubes 23
10. Tongue Forceps and Glossotilt 24
11. Apparatus for Opening Clenched Jaws 25
12. Frame for Adapting Vertical Cylinders to Foot Use 47
13. Nitrous Oxide Cylinders (upright and angle) 48
14. Complete Nitrous Oxide Apparatus 49
15. Barth 3-way Nitrous Oxide Tap 50
16. Hewitt’s Wide-bore Nitrous Oxide Valves 50
17. Ash’s Modification of Paterson’s Nasal Gas 58
18. Hewitt’s Apparatus for Nitrous Oxide and Oxygen 63
19. Diagram to Illustrate Action of Hewitt’s and Teter’s
Gas-Oxygen Methods 67
20. Details of Clark’s Expiratory Valve 68
21. The Clarke Gas-oxygen Apparatus 69
22. Marshall’s Sight-feed Gas-oxygen Apparatus 70
23. Clover’s Ether Inhaler, with Nitrous Oxide Attachment 77
24. Clover’s Inhaler, Diagram of a Vertical Section 78
25. Hewitt’s Wide-bore Ether Inhaler 80
26. Ormsby’s Ether Inhaler 81
27. Bellamy Gardner’s Mask and Ether Dropper 83
28. Four Photographs to Illustrate the Administration of Open
Ether 84–5
29. Shipway’s Warmed Ether Apparatus 91
30. Diagram of Intratracheal Apparatus 98
31. Electric Blower for Intratracheal Method 99
32. Kelly’s Intratracheal Apparatus 100
33. Shipway’s Intratracheal Apparatus 102
34. Hill’s Direct Laryngoscope 104
35. Diagram of Blood-pressure Curves Obtainable with
Chloroform 110
36. Vernon Harcourt’s Percentage Chloroform Inhaler 115
37. Chloroform Mask 116
38. Chloroform Drop Bottles 117
39. Junker’s Chloroform Apparatus 119
40. Tube of Ethyl-Chloride 122
41. Ethyl-Chloride Inhaler 124
42. Guy’s Gas and Ethyl-Chloride Inhaler 128
43. Details of Guy’s Inhaler 129
44. Diagram of Gas-Oxygen Method Introduced by Dr Guy and
the Author 130
45. The Guy Ross Gas-Oxygen Instrument 131
46. Rendle’s Cone 135
47. Clover Inhaler adapted for the Ethyl Chloride-Ether
Sequence 139
48. Two Photographs illustrating Sylvester’s Artificial
Respiration 146–7
49. Sitting-up Posture for Operations upon the Head and Neck 159
50. O’Malley’s Posture for Intra-nasal Surgery 160
51. All-metal Syringe for Infiltration Anæsthesia 176
52. Infiltration of the Brachial Plexus 183
53. Needle and Syringe for Spinal Analgesia 194
54. Position of the Patient for Spinal Analgesia 196
INTRODUCTION.
The securing of a safe anæsthesia during operations is more important
than ever before, partly because of the mere number of operations,
and partly because of the greater extent to which other operative
risks--hæmorrhage, shock and infection--have been overcome. The risk
from the anæsthetic is now so very small that the joint aim of the
surgeon and anæsthetist to abolish it altogether is not far from
being accomplished. The author of this volume has done a good deal to
accomplish this end, and it is a matter of congratulation that he has
now published an account of his methods, so that a larger circle may
benefit from his teaching and his experience.
The author very properly goes further and maintains that anæsthesia
must not only be safe but must also be good; good anæsthesia is
absolutely vital to good surgery. Only a generation back many surgeons
professed to see no difference as to who gave the anæsthetic; at the
present day no one willingly embarks upon a difficult operation without
the aid of a skilled anæsthetist.
In various parts of the book the author has very rightly laid great
emphasis upon the influence which the work of the surgeon has upon
that of the anæsthetist. The latter may learn much from an occasional
glance at the field of operation. He should not interest himself in the
details of operative procedure to the distraction of his mind from his
own responsibilities; but he can, in abdominal surgery, see for himself
whether the muscles are properly relaxed, and observe the state of
operation, so that he can when necessary deepen the anæsthesia in good
time, while not maintaining deep anæsthesia when a light one would
suffice. Finally, he can check his other sources of information as to
the condition of the circulation by noticing the force with which cut
arteries spout, the colour of the blood and the size of uncut veins.
Like other branches of medicine, adequate study as well as practical
experience is required in order to master the art of administering
anæsthetics, and that a reliable manual of instruction is essential,
goes without saying; I feel on perfectly safe ground in recommending
this book as such both to the student and the practitioner.
ALEXIS THOMSON.
PREFACE.
This little book is an attempt to present to the student and
practitioner a condensed account of modern anæsthetic views and
practice. In choosing a general scheme I have tried to lay emphasis
upon the relation of anæsthesia to general medical science rather than
upon elaborate descriptions of anæsthetic apparatus and methods which
a few years hence may be superseded. I have therefore devoted the
first four chapters to an account of the various forces which modify
the physiology of the patient during an operation under a general
anæsthetic, in so far as we at present understand them. I trust that
they will prove not only a sound basis for the information given in
the rest of the book but also a help towards forming a judgment upon
new methods and appliances as and when they meet the attention of the
reader.
In making a selection of drugs and appliances for description, I have
eliminated those which do not appear to me to have any real sphere of
usefulness.
The account of nitrous oxide and oxygen has been given in some
detail. Both the profession and the lay public have arrived, through
the experiences of the war, at a more just appreciation of the
possibilities of this combination than was at all general before
the year 1914. At the present day, no one who proposes to engage in
anæsthetic work can afford to remain unpractised in its administration.
I have an apology to make to my women readers. Throughout the book,
when speaking of the anæsthetist, I have presumed the male sex. Such
phrases as “his or her” and “he or she” are tedious and inelegant, and
their omission must not be taken as forgetfulness on the author’s part
that women frequently make very good anæsthetists.
Professor Alexis Thomson has added to the many kindnesses I have
received at his hands by writing the Introduction which immediately
precedes this Preface, and I wish to express my sincere thanks to him
for such a valuable addition to the book.
From Mr David Wallace, F.R.C.S.E., I have received much valuable help
and guidance in anæsthetic matters. It was largely due to his kindly
assistance and moral support that I was encouraged to persevere with my
early attempts to use nitrous oxide and oxygen in major surgery. The
hints which are given in connection with Genito-Urinary Surgery are
also derived from him.
The chapters upon Local and Spinal Anæsthesia are entirely the work of
Mr Wood, to whom I must express my gratitude for the admirable way in
which he has done the work.
I must also thank Dr Torrance Thomson most sincerely for his useful
contribution in chapter X, which constitutes a complete
monograph upon Intratracheal Anæsthesia.
To Dr Wm. Guy I am indebted for the photographs which appear in the
book, and I must express my sincere gratitude to him for the trouble he
has taken in the matter.
Much thanks are also due to the following firms who have been kind
enough to lend illustrative blocks:--Messrs Claudius Ash & Co. Ltd., G.
Barth & Co., De Trey & Co., J. Gardner & Son, Allen & Hanbury’s Ltd.,
Meyer & Phelps, Coxeter & Son, Down Bros., Ltd., Krohne & Sesemann, and
Mr J. H. Montague.
Lastly, I must express my high appreciation of the courtesy which the
publishers have shown to me, and of their generosity in the matter of
illustrations.
J. STUART ROSS.
_October 1919._
Handbook of Anæsthetics.
CHAPTER I.
PHYSIOLOGICAL ACTION OF ANÆSTHETIC DRUGS.
Every anæsthetic drug has certain pharmacological peculiarities of its
own, but all have much in common, and it is to these common features we
shall first direct our attention.
Reaching the blood stream by absorption from the lung alveoli, the drug
enters into loose combination with the red blood corpuscles; a small
proportion only is carried in the plasma. Within the corpuscles it
must of necessity displace a certain proportion of the oxygen normally
carried: this factor is of great importance only in the case of nitrous
oxide gas, which readily displaces the larger part of the normal oxygen
content. In the case of other anæsthetics, the same process occurs; but
to a less extent. Detailed figures of the extent to which the blood
gases are altered in various stages of chloroform anæsthesia will be
found in Appendix III.
The actions of individual drugs upon the circulatory, respiratory,
and excretory systems differ so considerably that a small section
has been devoted to this subject in each of the chapters devoted to
nitrous oxide, ether, and chloroform respectively. One feature is,
however, dependent upon the _state of anæsthesia_ rather than
the action of the particular drug, and that is a certain slight fall
of blood pressure. This phenomenon is seen even in natural sleep, and
is presumably due simply to lack of normal stimuli such as tactile,
visual, and auditory impressions which in the ordinary circumstances of
life, help to maintain the tone of the vasomotor system. That such a
fall is due to the _state_ of anæsthesia admits of little doubt,
but the fact is not always easy to demonstrate since each of the drugs
themselves have a marked influence upon the B.P., which masks the pure
effect of the anæsthetic sleep.
Action upon the Nervous System.
It is in this system, of course, that we look for the characteristic
action of anæsthetics, since if we had a choice, it is the brain
only which we should desire to influence by our drug. It used to be
said that anæsthetics paralyse the brain from above downwards, but
that is only approximately true. More correctly we may say that the
more highly developed parts of the brain are earliest affected, and
that those portions, such as the vital medullary centres, which man
shares in common with his humbler zoological relatives, maintain
their activity until the last. Moreover, it must be remembered that
before any brain centre succumbs, it passes through a preliminary
stage of _excitement_, varying in intensity with varying drugs
and also with different types of patients. Those who are accustomed
to administer to their nervous centres repeated large doses of such
nerve poisons as alcohol and tobacco, may show very evident signs of
this preliminary cerebral irritation during the process of induction
of anæsthesia; so do also the unhappy possessors of nervous systems
deranged from other causes such as epilepsy.
_The first centres to be attacked are those of thought and perception._
The patient is incapable of coherent reasoning, and loses touch to
some extent with impressions from the outside world. _Muscular sense
and co-ordination next become affected._ Although still able to move
the limbs or the head, movements are incoherent, and if at this stage
the patient were put upon his feet, he would stagger as he does in
alcoholic intoxication. By this time _sensation_, both tactile and
special, begins to be affected. The patient is no longer cognisant of
pain,--if cut he would at any rate not have a remembrance of pain.
_The special senses_ are at this stage also lost, one of the last to
go being the auditory sense, a point which is sometimes forgotten by
those inclined to talk while anæsthesia is being induced. _Muscle tone
is the next function_ to be lost, and at this stage all movements on
the part of the patient should cease except those of respiration. _The
reflexes_ disappear at varying stages: the spinal reflexes, _e.g._
the knee-jerks, disappear fairly early, probably before muscle tone
is entirely abolished, but certain other reflexes persist to a later
stage. Those which are of most interest to the anæsthetist are the
conjunctival, corneal, and pupillary reflexes of which he will find
full details in Chapter V.
Lastly the _vital medullary centres_, respiratory, vasomotor, and
cardiac are overcome, and at this stage we have passed beyond the
stage of a proper anæsthesia into that of over-dosage. In passing it
may be observed that the level at which one endeavours to work is that
indicated by the loss of muscle tone and of some of the reflexes and
the full activity of the medullary centres, and that an anæsthetic is
good or bad according as it gives a wide or narrow margin between these
two events.
Upon the _peripheral nerves_, anæsthetics have much less effect than
on the central nervous system. Faradisation of a _motor nerve_ will
in the deepest anæsthesia still cause immediate contraction of the
muscles supplied by it, showing that the conductivity of the nerve
is unaffected. Of far more importance, however, is the fact that
the _sensory nerves_ are not paralysed. That pain is not felt by
the patient is due simply to the loss of function of the cerebral
sensory centres; _injury to the nerve still causes an impulse to be
transmitted to the brain_. Since no operative procedure can be carried
out without more or less trauma (injury) to sensory nerves, we may
picture the brain of the patient undergoing a surgical operation while
under a general anæsthetic, as being constantly bombarded by sensory
stimuli, which though not consciously appreciated by the sleeping
patient, are yet capable of producing reflex effects of a definite
character, the importance of which to the work of the surgeon and
anæsthetist it is difficult to exaggerate, and of which a condensed
account will be found in the succeeding chapter.
CHAPTER II.
SHOCK AND ANÆSTHESIA.
Under this short and convenient title, the author proposes to discuss
all the changes observable in the patient’s condition, the causation
of which can be traced to the procedure of the surgeon. The use of
the term _shock_ was at one time, and by some teachers still is,
restricted to a definite clinical condition. The patient was described
as lying pallid and almost pulseless, with dilated pupils, cold
sweating skin, and gasping, irregular respirations. In the view more
generally taken to-day, that is but the extreme and final manifestation
of a syndrome, which any patient who suffers trauma (whether inflicted
accidentally or by the surgeon) exhibits in a greater or less degree,
and from which general anæsthesia protects a patient to a very limited
extent only.
Professor Crile, to whose work we owe so much of our knowledge on this
subject, has said, “In general anæsthesia, part of the brain only is
asleep.” Though consciousness is abolished, many parts of the brain
are quite capable of responding to _centripetal impulses_ passed
to the brain through sensory nerves injured by the knife. A full
account of the changes demonstrated by Crile in some of the cells of
the grey matter of the brain as a result of such stimuli, and of the
interpretation put upon these by their discoverer, is not suitable for
a text-book of anæsthesia. It is sufficient to say that such changes
have been discovered, and that their occurrence as a result of trauma
is not prevented by inhalational anæsthesia. Such changes, though of
the utmost interest scientifically, cannot be demonstrated clinically,
and it is to alterations of _blood pressure_ and of _respiration_ that
we must look for clinical evidence of the effects of _shock stimuli_.
[Illustration:
FIG. 1.--Shock--Blood pressure of a dog undergoing
laminectomy under general anæsthesia (Grey and Parsons.)
(_Reproduced by kind permission of the Authors._)]
With every incision by the surgeon, sensory nerve twigs are of
necessity injured. The fibres found in sensory nerves are, it will
be remembered, either pressor, or depressor--that is, stimulation of
them, causes either an increase or decrease of the blood pressure,
the depth and frequency of respiration being usually affected in the
same direction as the B.P. That such changes do commonly occur is
easily recognised by clinical observation. The veriest beginner in
anæsthesia soon learns to expect a deeper, quicker respiration and a
stronger pulse as soon as the operation has begun. These changes have
been studied experimentally upon animals and upon the human subject by
the use of the sphygmomanometer: Fig. 1, drawn from Grey & Parson’s
Arris and Gale Lectures of 1912, shows a tracing from a dog undergoing
laminectomy under general anæsthesia, and gives a good idea of the
early evidences of shock.
* * * * *
We may condense the results of much work on this subject under the
following headings:--
(_a_) Most stimuli from the field of operation cause a
sharp rise of blood pressure, followed by a sharp fall.
(_b_) Successive stimuli delivered quickly one after
another add their effects together, the total result being
considerably greater than from one severe trauma.
(_c_) After a time, the pressor effect of stimuli begins
to lessen: the animal or patient “wears out,” and finally no
pressor result can be obtained by the most massive stimulation:
the curve of B.P. steadily falls: the condition of full surgical
shock is produced.
(_d_) The tearing or pulling of tissues produces more
powerful stimuli than the use of a sharp knife, and, therefore,
brings on the full condition of shock more rapidly.
(_e_) Stimuli from some tissues cause much more reflex
effect upon the organism than from other less sensitive
structures. This is well exemplified when an abdominal section
is in progress. Incision of skin causes immediate response in
deepened respiration and higher B.P.: division of the fascia
very little effect. If the muscle is divided by the knife, again
little reflex effect is noticeable, but if it be stretched and
split by the fingers, the response is powerful. The parietal
peritoneum, however delicately handled, is one of the most
sensitive structures in the body, and, unless the patient is
fully under at the stage either of opening or closing this
layer, actual breath-holding or straining will occur. On the
other hand, incision or suture of the hollow viscera will cause
practically no response however light the anæsthesia, provided
these structures, and their connections with the parietes, are
not pulled upon.
(_f_) Stimulation of certain selected areas, of which the
spermatic cord is a well-known but by no means the only example,
results in an almost immediate fall of blood pressure with
little or no preliminary rise. In the operating theatre, we
sometimes see faintness or syncope arising quite suddenly during
operations in such regions. This subject is explained more fully
in Chapter XVI. under the term “Reflex Syncope.”
Illustration:
FIG. 2.--Combined blood pressure chart showing
the average of a number of experiments.--A--Under nitrous
oxide and oxygen. B--Under ether. At each spot marked
x, a trauma (burning of the paw) was inflicted. (After
CRILE.)]
(_g_) While no general anæsthetic protects absolutely
from shock stimuli, some anæsthetics give more protection than
others. Nitrous oxide is the most effective in this respect,
its powers being two and a half times greater than that of
ether: chloroform is even less effective than ether (_see_
Fig. 2).
(_h_) The claim made by the older generation of surgeons
that shock could be prevented by the use of a _deep_
anæsthesia, and that the occurrence of any “Reflex syncope” was
always a sign of too light an anæsthesia cannot be made good. At
the same time, it must be admitted that too light an anæsthesia
does increase the likelihood of shock. _Prolonged deep_
anæsthesia, on the other hand, produces by itself a condition
indistinguishable from shock, with the single exception of
nitrous oxide gas.
(_i_) Operative shock is predisposed to by several factors
of which the following are the most important:--
1. Hæmorrhage before or during operation.
2. Sepsis.
3. Fear.
4. Prolonged starvation.
5. Certain diseases, especially hyperthyroidism
(exopthalmic goître).
Theories of Shock.
So far as we have touched in the above upon theory, it has been theory
which receives general acceptance and which accords with known clinical
facts. When we come to discuss _the reason why blood-pressure falls
in shock_, we are in more debatable country.
Crile’s original view was that the upstroke seen in such charts as
shown in Fig. 1 are caused by reflex vaso-constriction, and that the
final fall of B.P. was due to exhaustion of the vaso-motor centre.
This view he does not seem to have modified as a result of his later
discovery of degenerative changes in certain cells of the grey matter
of the brain.
Other workers, J. D. Malcolm in this country, and Yandell Henderson,
of Yale, U.S.A., maintain an opinion diametrically opposite. In their
view, in fully developed shock, the vessels are in vaso-constriction,
and the circulation is arrested from undue internal resistance to blood
flow.
A third explanation of lowered B.P. has been offered, and while its
significance is not understood, there is fairly general agreement as
to its validity. This factor is a _reduction in the total blood
volume_--an oligæmia. No one has as yet demonstrated to what region
or organ the missing blood volume has retreated.
YANDELL HENDERSON’S ACAPNIC THEORY OF SHOCK.
Acapnia is a condition in which the CO_{2} content of the blood and
tissues has been brought to too low a level. Those who climb mountains
suffer from it, and so do those who breathe rapidly and heavily for a
prolonged period. Carbon dioxide is necessary for the vigour of the
respiratory centre, of which it may be termed the natural regulator.
Moreover, the heart and the great veins which empty into it require a
certain proportion of CO_{2} in the blood.
Admittedly, patients inhaling anæsthetics do on occasion breathe too
deeply. Sometimes they do so voluntarily before losing consciousness,
sometimes reflexly as a result of such a manœuvre as stretching the
sphincter ani. Do they thereby bring their CO_{2} down to a level which
does serious harm and which can be considered a cause of collapse under
anæsthesia? Henderson says they can and do: most other workers deny the
possibility.
[Illustration:
FIG 3.--Diagram (after CRILE) to illustrate
anoci-association. In “A” the trauma is inflicted on the leg,
and the brain being wholly unprotected, considerable shock
is suffered. In “B” the brain is protected by inhalational
anæsthesia from the effects of fear, etc. In “C” the sensory
nerves from the seat of trauma are blocked by novocaine,
and the brain also protected by inhalational anæsthesia.
Theoretically no shock is suffered.]
Prevention and Treatment of Shock.
There are many theories of shock but only one anti-shock technique
which will bear examination. Founding upon his own theory, Crile about
1913 elaborated his ANOCI-ASSOCIATION method of which the
following are the leading features (_see_ Fig. 3):--
(_a_) _Prevention of fear._--Every member of this team is taught
the all-important art of so dealing with the patient that no
unnecessary fear is allowed to remain in his mind. That art does
not consist in endless repetition of the phrase, “Do not be
frightened,” but rather in each so bearing himself or herself
before the patient that he may gradually acquire the conviction
that he is surrounded by careful, kindly, and skilful persons
who are doing for him what they do for hundreds of others, and
doing it with an expectation of his early and complete recovery
so certain that they do not need to put it into words unless
definitely questioned. Such an art is not acquired in a day, and
some unhappy few are so constituted that they can never acquire
it.
As a further preventative of fear, and also for other reasons
explained in Chapter vi., the patient receives a dose of morphia
(⅙th grain, with ¹⁄₁₂₀th grain atropine, hypodermically) three
quarters of an hour before operation. Some surgeons go further,
and give a sedative the night before operation. Veronal gr.
viii. is the favourite prescription of Prof. Alexis Thomson of
Edinburgh.
(_b_) The sensory nerves are “blocked” by infiltration with
novocain. By the systematic use of local in conjunction with
general anæsthesia, the harmful stimuli from the area of
operation are prevented from reaching the brain. For the details
of this measure, the reader is referred to Chapter xx.
(_c_) The anæsthetic of choice in Crile’s practice is nitrous
oxide and oxygen (_see_ Chapter vii.).
The whole of this technique has not been generally adopted as a
routine, but nevertheless the teachings of Crile have greatly
influenced the mind and practice of most surgeons and anæsthetists.
Traces of that teaching are to be found everywhere in the organisation
built up during the Great War to save as many as possible of the lives
of badly smashed men. At no previous time in the history of surgery was
the problem of shock so pressing, and a brief resumé of the methods
adopted is here set down, as an example of how shock should be dealt
with.
[Illustration: FIG. 4.--Lane’s apparatus for
subcutaneous infusion of saline solution.]
Treatment of Shock among the Casualties of the War.
The first essentials demanded were the most careful organisation, the
provision of equipment far in advance of most home civilian hospitals,
and of surgical teams specially trained to a high level of excellence.
Upon recovery from the field, the injured man received at the ADVANCED
DRESSING STATION, such first aid dressing as was necessary, and a
substantial dose of _morphia_. When the latter had had time to take
effect, the case was passed back to the Field Ambulance (where he
received his first dose of antitetanic serum), and from there to the
CASUALTY CLEARING STATION. During every stage of the journey, he
received as much _warm fluid nourishment as possible_. Arrived at
the C.C.S., the severe case was passed first into the RESUSCITATION
WARD. This department, under the charge of a specially trained M.O.,
concentrated largely upon two measures--the thorough _warming_ of the
patient, and the replacing as far as possible of the fluids lost to
him by hæmorrhage and shock. The warming in many C.C.S.’s was effected
by electric radiant heat baths. The fluids were replaced either by
way of infusing blood from another patient, or by the use of _gum
saline solution_. Introduced into a vein, the action of this solution
persists for a much longer period than that of ordinary saline, being
less easily lost by osmosis through the capillaries into the tissues.
From the resuscitation ward, the patient passed to the OPERATING
THEATRE. Though the full technique of anoci-association was not always
possible, the maxims which Crile had sought to inculcate into the
practice of surgery influenced the work of surgeons and anæsthetists
very profoundly. Nitrous oxide and oxygen was used for all the severely
shocked cases, and infiltration with local anæsthetics where feasible
and necessary.
Subcutaneous Infusion of Saline.
For those who do not feel bound to adopt the Crile technique this is a
simple measure which does much to minimise shock in prolonged abdominal
operations. Saline infusion into a vein is so rapidly excreted that its
influence is very fugacious, but if the fluid be introduced under the
skin during the period of operation it is slowly absorbed as required
by the blood. Sir Arbuthnot Lane is a strong advocate of this measure.
Fig. 4 shows a suitable apparatus. The needles are thrust into the
loose areolar tissue under the breast, one on each side, and a pint or
more of fluid is _slowly_ run in from the reservoir.
CHAPTER III.
ASPHYXIA OR ANOXÆMIA.
Some degree of asphyxia is a common complication of inhalational
anæsthesia: indeed some small degree of it is almost unavoidable. It
is hardly too much to say that the difference between a good and a bad
anæsthetist is that the one recognises and deals with asphyxia in its
early stages, while the other allows it to assume serious proportions
before he becomes aware of its existence. The man who only realises
that asphyxia is present when the patient is deeply cyanosed and has
ceased to be able to draw any air at all into his chest may know much
of the physiology of anæsthetic drugs, and be well up in complicated
anæsthetic apparatus, but knows nothing of the proper practice of
anæsthesia.
Asphyxia arises during anæsthesia from several causes. In the first
place, the drug which the patient is inhaling and absorbing into the
blood, turns out from his red corpuscles a corresponding quantity
of oxygen. While this is only seen in its extreme form in the case
of nitrous oxide gas, it is a factor acting even in the case of
other anæsthetics. Secondly, during deep anæsthesia, the respiratory
centre may be somewhat depressed, and the force and frequency of the
respiratory act diminished. Thirdly, the respiratory passages may be
partially or wholly occluded from _mechanical_ causes. This is far
the most important type of asphyxia, being the most common, the most
fatal, and the most easily prevented.
Common Causes of Mechanical Asphyxia.
(1) CLENCHING OF THE JAWS arises not uncommonly during anæsthesia,
being specially frequent towards the end of the induction period.
Since a very large proportion of individuals have nasal passages
insufficient in bore to carry the full volume of respired air,
respiration must be obstructed if the jaws are clenched.
(2) FALLING BACK OF THE LOWER JAW AND BASE OF THE TONGUE OVER THE
EPIGLOTTIS.--This is always liable to happen after the muscles are
deeply relaxed.
(3) MUCOUS OR BLOOD OR A FOREIGN BODY IS DRAWN BY INSPIRATION INTO
THE AIR PASSAGES.--Changes of position of the head may release
mucous which has been gathering in some parts of the mouth or pharynx.
For instance, if the head has been lying on the side for some time, a
pool of mucous or saliva commonly gathers in the most dependent cheek,
and unless this is mopped out before the head is brought into the
mesial position, this pool will be suddenly tipped backwards, and very
probably drawn into the larynx. Again, in operations upon the nasal or
oral cavities, blood is always liable to be inspired, and not a few
teeth have found their way into the air passages in the practices of
dental surgeons who do not take precautions against this accident.
(4) SPASM OF THE ADDUCTORS OF THE VOCAL CORDS is one of the most common
and most baffling incidents in anæsthesia. It announces its presence by
the commencement of _laryngeal stridor_, a high-pitched crowing noise,
which is as annoying for the surgeon and anæsthetist to hear as it is
detrimental to the progress of a smooth anæsthesia. Inspired mucous or
blood almost invariably sets it up, and the two conditions of fluid
in the larynx and narrowing of the glottis from approximation of the
cords, add their effects together, with resulting obstruction of a high
degree.
Laryngeal stridor, however, frequently occurs even when no fluid
has been inspirated. It may be set up as a reflex from the area
of operation. Dilatation of the sphincter ani, and removal of the
prepuce in circumcision, are two common examples of this. It is also
undoubtedly sometimes caused by giving too strong a vapour during the
latter part of the induction stage. Stridor unfortunately sometimes
occurs from no obvious cause at all, or to speak more correctly,
from causes which are at present not known to us. It is the author’s
belief that one of these causes may prove to be _morphia_ given as a
preliminary to inhalational anæsthesia. In his experience, stridor
has been more frequent with morphia than without, particularly if
chloroform be the anæsthetic chosen. Beyond that he cannot at present
go.
(5) PRESSURE UPON THE AIR PASSAGES OF NEOPLASTIC OR INFLAMMATORY
SWELLINGS IN THE NECK.--In such cases any obstruction which may
exist before induction will probably become intensified during the
process, and a complete arrest of respiration is not uncommon. Large
goîtres are the most common type of neoplasm to give trouble, and all
acute inflammatory conditions in the neck which extend towards the
trachea are notorious for their tendency to give cause for anxiety
during anæsthesia.
The Physiology of Asphyxia.
An animal, subjected to asphyxia, either mechanically or otherwise,
shows the following signs:--
(_a_) _Increase of the force and frequency of the
respiratory movements of chest and abdomen._ Even though
there be a complete mechanical obstruction, increased efforts
to breathe will still be made for some moments, although air no
longer passes in and out of the chest.
(_b_) There is a considerable rise of blood pressure owing
to a high degree of vaso-construction.
(_c_) The pupils dilate.
(_d_) Generalised convulsions.
(_e_) The animal succumbs finally from cardiac failure.
No heart muscle can continue to function properly if supplied
by the coronary arteries with venous blood. Moreover, the
heart pump has to act against the greatly increased peripheral
resistance induced by vaso-constriction. It must therefore be a
matter of time only when the strongest and healthiest heart will
cease to contract under the abnormal conditions of asphyxia.
There are in asphyxia, two alterations in the blood-gasses, _i.e._
lack of oxygen and increase of CO_{2}. The action of these two
conditions have been differentiated by experimental work (Starling,
Kayala, Jerusalem), and one can say definitely that the excess of
CO_{2} is the cause of the increased activity of the respiratory
efforts, and that the remaining phenomena are due to oxygen starvation.
This point is of some importance in considering anæsthetic methods
in which re-breathing (breathing in and out of a bag) is practised.
The use of such methods has often been thoughtlessly condemned as
“poisoning the patient with his own CO_{2}.” Within the limits usually
practised, a re-breathing method does not involve any such risk,
provided oxygen starvation does not occur. This point is referred to
again in Chapter iv.
Clinical Signs of Mechanical Asphyxia in the Anæsthetised Subject.
The classical signs of asphyxia above described are hardly to be
expected in the operating theatre, but essentially the condition
of the patient who develops respiratory obstruction while under an
anæsthetic is similar to that produced experimentally in animals in the
laboratory. The changes most easily observed are as follows:--
(1) _Alteration of the colour._--Cyanosis shows itself earliest
in the lips, and the lobules of the ears,--later the whole face
becomes dusky.
(2) _Dilatation of the pupil_, which ceases to respond to the
stimulus of light.
(3) _The respiratory movements increase in depth and
frequency._--The chest and abdominal walls heave forcibly; but
(4) _The volume of air passing in and out of the glottis is
diminished._--In complete obstruction, of course, none passes
at all. In passing we may draw the moral that persistence of
chest movements is no proof of the passage of air in and out
of the chest: that can only be proved by hearing the movement
of air through glottis and mouth or nose, or feeling it on the
delicate skin of the back of the observer’s hand.
(5) _True convulsions are not seen_, unless we may consider
the jactitation of deep N_{2}O anæsthesia as such (see Chapter
VII.). Nevertheless, there are obvious and most valuable signs
of asphyxia to be found in the muscular system often quite
early. These consist in the incidence of _muscular rigidity_,
which is frequently observed first in the muscles of the
abdominal wall. A surgeon performing laparatomy will notice
at once the occurrence of this phenomenon, than which hardly
anything can complicate and delay his task more effectively.
The anæsthetist who knows his work will, upon hearing from the
surgeon a complaint as to the rigidity of the abdominal wall,
devote his attention first to securing a perfectly free air-way
before deciding that a deeper anæsthesia is required.
[Illustration: FIG. 5.--Vicious circle of asphyxia.]
Prevention and Treatment of Asphyxia.
Once asphyxia, especially mechanical asphyxia, has begun, it almost
invariably tends to get worse. The engorgement affects among other
venules, those which run under the mucous membrane of the respiratory
tract, still further obstructing the passage of air. The muscular
rigidity, moreover, soon manifests itself in the adductors of the
vocal cords and the muscles which close the jaws: the patient has
thus entered into a “vicious circle,” Fig. 5. It is evident that the
prevention of the earliest signs of asphyxia is to the anæsthetist a
matter of vital interest. The cardinal points to watch are as follows:--
(1) Keep the neck of the patient as far as possible in a natural
position, _i.e._ do not either flex or extend the head unduly
upon the body unless the nature of the operation demands such an
unusual position.
(2) Maintain a free passage for air either through the nose or
the mouth.
(3) Keep the lower jaw in good position throughout the
administration.
(4) Avoid turning the face from the lateral to the dorsal (face
up) position unless essential. If it has to be done, be careful
first to mop out any “pool” from the dependent cheek.
(5) Deal as effectively as possible with the earliest appearance
of laryngeal stridor.
Let us see how in a normal case, these rules can be applied. With
the patient lying (or, in exceptional circumstances, sitting) in a
comfortable position, the shoulders and head raised above the rest of
the body and the face looking upwards (or straight forwards, in the
case of the sitting patient), the anæsthetic is begun slowly, and the
patient encouraged to take his time and to breathe naturally. At this
stage the jaw needs no support, the muscles being neither relaxed by
deep anæsthesia, nor spastic from asphyxia. With the advent of muscular
relaxation, the head is turned to one side, that which is opposite to
the side on which the surgeon will be working, being usually chosen.
We must now determine whether the patient can breathe best through the
mouth or the nose, and make sure that the channel chosen is as free as
possible. In the majority of cases it will be found that respiration is
oral, and that all that is necessary is to support the lower jaw by a
finger hooked into the depression just below the symphysis mentes. The
hands of the anæsthetist, therefore, take up a position from which in
nine cases out of ten they will never require to be moved.
_The hand of the side toward which the patient’s face is turned_
supports the jaw and keeps the face-piece or mask adapted to the face.
The middle finger is pressed into the space below the symphysis mentis,
and _exercises traction forwards and a little upwards_, thus preventing
the jaw from slipping backwards; the index finger lies along the lower
part of the mask, maintaining adaptation between it and the chin; the
thumb bears on the mask higher up, keeping its upper part pressed
against the bridge of the patient’s nose, and also serving as a _point
d’appui_, or fulcrum, from which the jaw traction by the middle finger
can conveniently be exercised. This grip once learnt is not fatiguing
to the hand, and is in the author’s opinion one of the essential points
for the beginner to master (_see_ Fig. 28C, page 85).
_The opposite hand_ holds the drop bottle, if the method in use is
an open one, the wrist resting upon the uppermost side of the patient’s
head.
[Illustration: FIG. 6.--Hewitt’s dental props.]
Fig. 28C shows this grip in operation, while Fig. 28D shows the
alternative frequently adopted. This alternative has various
disadvantages. It covers up a larger part of the patient’s face than
the method recommended, and it tends to tilt the mask sideways. The
little finger is supposed to be hooking forward the jaw by pressing
behind its angle, but such a method is very fatiguing if in use for
more than a few moments.
In a proportion of cases, it is found that a free air-way cannot be
maintained by these simple measures. Upper or lower teeth (or both)
may be missing and traction upon the lower jaw only closes the mouth
the more firmly. In most of these cases, the difficulty can be met
by the use of the _dental prop_. These are made in various sizes and
shapes, of which the best known are Hewitt’s and Bellamy Gardner’s
(_see_ Figs. 6 and 7). The latter are made of aluminium and are of
small size only. They are the most convenient for cases with teeth
both in the upper and lower jaw, but who suffer from a receding lower
jaw not easily kept forward unless the prop is used as a rocker, as it
were, upon which it can be slid forward. Hewitt’s props are of plated
metal, with lead on the cups, to avoid injury to the teeth. They are
made in five sizes, of which the middle and larger are very convenient
for cases in which one or both rows of teeth are missing.
[Illustration: FIG. 7.--Bellamy Gardner’s Dental
Props.]
[Illustration: FIG. 8.--Phillips’ modification of
Hewitt’s artificial airway.]
For cases entirely without teeth, and in which a large flabby tongue
is prone to fall back over the epiglottis, the mouth tube (Fig. 8) is
very convenient. The rubber shank lies along the top of the tongue, the
metal end lies between the gums. As originally introduced by Hewitt,
the air-way was circular in cross section, but the flattened model
figured is a distinct improvement. It was introduced by Dr Phillips.
[Illustration: FIG. 9.--Silk’s nasal tubes.]
Occasionally one decides to facilitate nasal rather than oral
breathing, and if the natural passages are inadequate, recourse may be
had to the passage of a short piece of drainage tube of the calibre of
a number 10 catheter, and about 3 inches in length. With such a tube
in one or both sides of the nose, reaching from anterior to posterior
nares, nasal respiration is usually possible even in much obstructed
noses (Silk). (Fig. 9.)
[Illustration: FIG. 10A.--Bellamy Gardner’s
tongue-clip.]
[Illustration: FIG. 10B. Ring tongue
forceps.]
[Illustration: FIG. 10C. Glossotilt.]
[Illustration: FIG. 11A.--Boxwood wedge for
opening jaws.]
[Illustration: FIG. 11B.--Wedge for opening
jaws.]
[Illustration: FIG. 11C.--Mouth gag.]
If proper and timely use be made of one or other of these simple
devices, the use of the _tongue forceps_ is rarely necessary.
Occasionally, however, it may be required, and a suitable appliance
should always be at hand for an emergency. Fig. 10 shows two types. The
little clip of Mr Bellamy Gardner is preferable to the ring type, the
passage of the spike through the tongue substance producing less after
pain, than the bruising following the use of the other instrument. The
third drawing in Fig. 10 is of an instrument not much known outside
Edinburgh; it is called a glossotilt, and is intended to lever forward
the base of the tongue, as an alternative to nipping the tip of the
organ with forceps, and has, in the opinion of some, various advantages.
Before using either mouth prop or tongue forceps, it is occasionally
necessary to use some mechanical means to lever open a tightly clenched
jaw. The earlier one interferes in a case of mechanical asphyxia, the
less necessity will exist for the use of such means. Fig. 11 shows two
well-known mouth gags, and also a box-wood wedge, the use of which is
less liable to injure teeth than a metal instrument. If a gag is used,
the blades when closed should lie the one behind the other, not side
by side. This ensures a minimal thickness to be inserted between the
tightly clenched teeth.
Treatment of Laryngeal Stridor.
This is of necessity difficult since the causation of the condition is
in many cases obscure. _The error_ common to most beginners, and to
many who would resent such a title being applied to them, is to regard
the appearance of stridor as an indication to _deepen the anæsthesia_.
Whether the cause lie in local irritation of the laryngeal mucous
membrane or in some stimulus from the area of operation, the condition
is presumably always essentially a reflex spasm of the adductors of
the vocal cords, but it is a _reflex which may persist even in an
anæsthesia so deep that the vital medullary centres are in peril_.
The preventive treatment consists chiefly in following the other rules
set forth above for the prevention of asphyxia with such faithful care,
that the patient never enters into the vicious circle of asphyxia of
which stridor is so prominent a feature. Patience in the induction
stage--the avoidance of _forcing_ the anæsthetic upon the patient--is a
safeguard not to be forgotten.
Once the condition has arisen, it saves time to _withdraw the
anæsthetic_ altogether, and to allow the patient to breathe nothing
but fresh air. Brisk friction of the lips with a rough towel often
does good, presumably by setting up a “cross reflex.” In severe cases,
a most valuable measure is the inhalation of pure oxygen, a cylinder
of which should always be at hand in the operating theatre. Even an
obstructed air-way will convey enough undiluted oxygen to reduce the
venosity of the blood, and so cut across the “vicious circle.”
So much for the treatment of the early stages of asphyxia, the more
advanced stages constitute one of the “accidents of anæsthesia,” and
are dealt with in Chapter XVI.
CHAPTER IV.
METHODS OF ANÆSTHETISING.
Certain terms such as “open method,” “closed method,” etc., are used in
describing different systems of anæsthetising, and it will save time
later if these are now defined.
The OPEN METHOD is one in which the drug is dropped or poured upon
a fabric stretched on a mask which does not lie in close apposition
to the face. If the student will experiment with such a mask as
Schimmelbusch’s, he will find that by no effort can he make its whole
circumference touch his face at the same time. Anæsthetics vapourised
from such masks must of necessity be inhaled freely diluted with fresh
air. These masks are only suitable for use with chloroform.
The PERHALATION METHOD.--This term is not used often, but it is the
most strictly correct name to give to the process commonly called
“open ether.” If the student will examine Bellamy Gardner’s open ether
mask (Fig. 27) he will find that it is deliberately shaped to lie
over its entire circumference in close apposition to the face of the
average patient. In actual use it is well however to make sure of this
apposition by the use of a ring of gauze as shown in Fig. 28A. Upon the
mask is stretched gauze of a thickness just as great as will permit
free respiration to take place through its layers. The whole bulk of
the respired air must pass _through the fabric_, none escaping between
the face and mask.
The term “SEMI-OPEN” is applied to various methods now rarely seen. One
of the best known of these was the anæsthetic cone, still used by a few
for C.E. mixture (_see_ Fig. 45).
The term “CLOSED METHOD” is applied to one in which the patient
breathes in and out of a closed bag. The Clover and Ormsby inhalers are
“closed” instruments. With this method the patient rapidly uses up the
oxygen of the contained air, and accumulates considerable CO_{2}; life
could not be sustained for any long period of time under such a system.
Oxygen must be supplied from time to time by permitting say one breath
in five to be taken from the fresh air instead of from that in the bag.
Alternatively, oxygen from a cylinder may be supplied by an accessory
pipe into the inhaler.
* * * * *
This method is also referred to as the RE-BREATHING METHOD.
* * * * *
The VALVED METHOD is used only with “gas” or “gas-oxygen.” The
facepiece fitting accurately, the patient draws all the volume of
his inspiration from the inhaler: his expirations he propels through
a valve, into the general atmosphere of the room. If nitrous oxide
unmixed with oxygen is being given, the patient suffers from oxygen
starvation even more rapidly and completely than in the re-breathing
method. During the induction period of gas anæsthesia, such oxygen
starvation is practised deliberately, and if not pushed too far is
harmless. It cannot, however, be continued for more than a brief space
of time. The admixture of oxygen to the vapour being breathed entirely
abolishes this unfavourable feature of the valved method.
There is, however, another consequence of the use of “valves” which
is unaffected by the addition of oxygen. Reference has already been
made to _Yandell Henderson’s acapnic theory_, and if under any form
of anæsthesia the patient can be reduced to a condition _of CO_{2}
starvation_, it will be when the valved system of administration is in
operation for a prolonged period. As a matter of experience, patients
breathing “on the valves” do often exhibit shallow respirations and
slight pallor which is rapidly and very strikingly remedied by turning
to the rebreathing method. One can hardly doubt that the improvement
is due to a gradual re-accumulation of carbon di-oxide in the blood and
tissues.
Two other terms referring not to the type of inhaler but to the method
of supplying the drug, are in use.
By the “DROP” METHOD, we mean one in which the anæsthetic is supplied
in a steady series of drops. The flow may be quick or slow, but it
always arrives on the mask in isolated drops of uniform size. Such a
method demands more constant attention than the next to be described,
but it is capable of yielding that even uniformity of vapour strength
so desirable in open methods.
THE DOUCHE METHOD is unfortunately far more commonly used by those
whose attention has never been drawn to the significance of the
difference between the two. Supplies of the drug rendered, say, every
twenty seconds cannot possibly give an even vapour strength.
“SINGLE DOSE” methods are of use chiefly in dental surgery. The patient
is charged up with the anæsthetic, and the operator has to begin his
work as soon as the mask is withdrawn from the face, ceasing as soon as
the patient shows any signs of recovering consciousness of pain.
Single dose anæsthetics are in a class by themselves. In order to
achieve success with them, special experience on the part of the
administrator and mutual confidence between operator and anæsthetist
are essential.
The period of anæsthesia available to the operator which any particular
“single dose” anæsthetic may be expected to yield is obviously a matter
of the first importance, and the table given in Chapter XIX.
will be found helpful in this connection.
CHAPTER V.
THE CLINICAL OBSERVATION OF THE PATIENT.
Stages of Anæsthesia.
Anæsthesia has been divided into four clinical stages corresponding
to the degrees to which the nervous system has been affected. The
boundaries between these stages are often ill-defined, but the
terminology has some value as facilitating description.
THE FIRST STAGE lasts from the commencement of inhalation up to the
time when volitional self-control is lost by the patient.
THE SECOND STAGE in the older text-books was said to be characterised
by struggling, shouting, and breath-holding. With a patient not
addicted to alcohol and with the anæsthetic skilfully administered,
this description is unduly lurid.
THE THIRD STAGE is that of full surgical anæsthesia.
THE FOURTH STAGE is that of over-dosage.
The Ocular Reflexes in Anæsthesia.
These give such valuable assistance to the anæsthetist that it will be
well to define and describe them as a preliminary. They are three in
number.
THE CONJUNCTIVAL REFLEX is best elicited by drawing the upper lid
upwards from the eyeball and retaining it in that position with one
finger, while with another finger the ocular conjunctiva is lightly
touched in the area of the inner canthus. If the anæsthesia is very
light, both lids attempt to approximate and close the palebral
fissure. The upper lid may slip down from under the retaining finger
and come into its proper place, while the lower lid is elevated. At
a deeper level of anæsthesia there is not complete action of the
orbicularis but merely of a certain part of it, so that all that is
observed is a _twitch inwards of the lower lid_. Even this form of the
reflex disappears before the corneal reflex.
THE CORNEAL REFLEX is elicited by pushing up the upper lid by one
finger and with the pulp of the _same_ finger lightly brushing the
centre of the cornea as soon as it is exposed, when we feel or see the
upper lid come back into position with a sharp definite twitch. The
examining finger must be slipped smartly out of the way as soon as
the cornea has been touched. Even in deep anæsthesia, a trace of this
reflex can usually be elicited if the little manipulation be properly
performed.
The conjunctival and corneal reflexes are frequently confused in the
mind of the student. The most common mistake made is to pin the upper
lid firmly somewhere in the region of the bony roof of the orbit,
to dab the eye far too vigorously, and to believe that no reflex is
present because no movement of the upper lid takes place. In the first
place, the upper lid cannot move if it is rigidly held against a bony
plate: in the second place, it is wholly unnecessary to inflict upon
the cornea more than the lightest of touches. Both these reflexes
are to be used with great discretion, undue frequency and excessive
vigour of touch being alike capable of setting up serious inflammatory
reaction.
THE PUPILLARY LIGHT REFLEX is elicited by shutting off light from
_both_ pupils for ten to twenty seconds and then smartly withdrawing
the protecting fingers and allowing as strong a light as possible to
fall on to the eye. The response of the ciliary muscle should _always_
be present; its absence is a certain indication of something wrong:
some sluggishness may be permissible under ether, but even that is
suggestive of trouble if chloroform is the anæsthetic.
The use of a preliminary hypodermic of morphia tends to make the pupil
somewhat smaller than normal, and to elicit the light reflex it may be
necessary to cut off illumination for a somewhat longer period than
if no morphia had been given. Nevertheless with a little care, the
light reflex should always be capable of demonstration even in the
morphinised subject.
The Observation of a Normal Case.
In the case of nitrous oxide and of ethyl chloride, the patient passes
through the various stages very rapidly, and the picture of anæsthesia
as induced by either of these two is therefore best described
separately. The following may be taken, therefore, as an account of
what is to be observed in the patient inhaling ether or chloroform,
unless a specific reference is made to one of the other anæsthetics.
FIRST STAGE.--The first sign that some effect is being produced in the
patient is usually the appearance of the movements of _swallowing_;
the hyoid and thyroid can be felt or seen to be moving in conjunction
with the muscles of deglutition. During this stage, the patient being
still to some extent under volitional control, there should be no other
movement noticed. The eyes are usually closed and the colour normal;
the respiration may be hurried by excitement, but judicious handling of
the patient will do much to minimise this.
THE SECOND STAGE is really entered when volitional control is lost.
It may be characterised by struggling and shouting by the patient,
even if the anæsthetic is properly administered; but with a healthy
patient and a good anæsthetist, all that usually occurs in the way of
movement by the patient is some rigidity of the limbs and a slight
attempt, perhaps, to lift the head from the pillow or a limb from the
couch. The breathing tends during the first part of this stage to be
light and is rarely entirely regular: slight pauses occur, usually
after an inspiration, less commonly after expiration. Serious “holding
of the breath” (after an inspiration) rarely occurs save in the type
of patient who is also struggling; if it does occur to a degree which
causes any blueness of the patient’s face (cyanosis), it usually calls
for the removal of the anæsthetic for a moment until normal breathing
has been resumed.
The colour of the face rarely departs much from normal during the
second stage, unless cyanosis from breath-holding intervenes.
The eyes are usually opened, as the second stage progresses, and the
eyeballs tend to rotate slowly in every plane. The pupils are usually
large, but react sharply to light. Both conjunctival and corneal
reflexes are brisk.
THE ONSET OF THE THIRD STAGE is marked by the appearance of muscular
relaxation. Any limb which the patient may have been holding rigidly
up sinks down on to the couch, and it will be found that if an attempt
be now made by the anæsthetist (as it should be) to turn the head of
the patient to one side or another, the muscles of the neck no longer
resist.
_The respiration_ also alters in type, losing its tendency to lightness
and irregularity, and becomes full, deep, and regular. In open ether
anæsthesia particularly, expiration commonly assumes a “blowing” type
very characteristic, and which to the trained ear is of itself an
indication that full surgical anæsthesia is present or at any rate not
far distant.
_The colour_ varies somewhat with the anæsthetic in use. With ether it
is usually somewhat higher than normal, and a trace of blueness may
be present if the method is the “closed” one. Anything more than a
trace, however, must be regarded as abnormal, whatever the method or
anæsthetic may be. With chloroform the colour is perhaps a little paler
than that normal to the individual.
_The eyelids_ are usually half open, and the eyeballs at rest looking
forward and slightly downwards. An extreme rotation downward may
usually be taken as a sign of very deep anæsthesia. _The pupil_ is, as
already said, always active to light, but its actual size varies with
the anæsthetic used. With ether, particularly “closed” ether, it may be
large (4–5 millimetres): with open ether, preceded by morphia, about
3–4 millimetres: a good chloroform anæsthesia usually exhibits a pupil
of only 2–3 millimetres, and if morphia has also been given, it may be
pin-point in size. Too much emphasis must not be placed, however, upon
the mere size of the pupil; that may vary within wide limits without
necessarily indicating serious abnormality. The essential point is that
the light reflex shall be brisk. A pupil of 5 millimetres reacting
sharply to light may be of no special moment: one of that size immobile
to light would cause real anxiety.
_The conjunctival reflex_ usually disappears fairly early in the
third stage: if briskly present, the anæsthesia is certainly a light
one, and probably insufficient for an abdominal section. _The corneal
reflex_ if properly taken in the way already described can usually
be elicited throughout the third stage. In an anæsthesia deep enough
for abdominal section it is, of course, not brisk, but we may say
generally that its entire absence is _presumptive_ evidence of a very
deep anæsthesia--probably undesirably deep. It must not be forgotten
that some local causes such as drying of the surface of the cornea
may cause it to disappear, and in case of doubt it is sometimes worth
while to wash out the eye with a little saline solution. If after doing
so the anæsthetist still finds the reflex not present he should be on
his guard. Provided, however, that the light reflex is still present
and colour and respiration satisfactory, he need not consider that the
patient is in any immediate danger.
Broadly speaking, then, the third stage, the stage which is called for
by the requirements of major surgery, is characterised by (1) full
regular respirations; (2) colour not much removed from normal; (3)
moderate sized pupil, larger in the case of ether than chloroform; (4)
conjunctival reflex faint or absent; (5) corneal reflex just present,
or, in a deep third stage, just absent; (6) light reflex present: these
may be regarded _as the signs of fully developed surgical anæsthesia_.
The absolute beginner may be so completely out of his reckoning as
to mistake the quietude of the later part of the first stage for the
appearance of the third stage. For the prevention of so gross an error
as that, the reader need only be referred to a patient study of the
foregoing. But even a man with considerable experience may frequently
be in doubt exactly as to _how far through the third stage his patient
has passed_. He may have attained a level which will permit an incision
to be made into the skin without movement on the part of the patient,
but not one which would relax the abdominal muscles sufficiently for
the peritoneum to be opened without eliciting considerable resistance
from the abdominal muscles. In such moments of doubt, the author is
accustomed to request the surgeon to make his skin incision, and
_observe the effect which this trauma has upon the depth, frequency,
and regularity of respiration_. This furnishes a most valuable guide
to the depth of anæsthesia. In a third stage of very light degree, the
respiratory rhythm will be interrupted and the breath held for a second
in inspiration. Apart from any other sign, that may be taken as an
index that the anæsthesia is very light--too light to permit of opening
the peritoneal cavity. In a very deep anæsthesia the respiration
is little affected by the skin incision, while at a moderate and
more desirable level the respiration is quickened and deepened, but
unaffected in the regularity of its rhythm.
THE FOURTH STAGE IS STAGE OF OVER-DOSE.--This stage is, of course,
never entered voluntarily. Its earliest signs are loss of all tone in
the muscles of expression, complete loss of corneal reflex, a widely
dilated pupil _insensitive to light_, and a type of respiration which
though definitely weakened may show occasional deep gasps. Circulatory
failure and cessation of respiration from failure of the medullary
centre are the closing phenomena of overdose.
The Circulation in Anæsthesia.
It will be perhaps noticed that in the foregoing, no reference has
been made to the examination of the pulse. This is not an oversight on
the part of the author. It is perfectly true that under any anæsthetic
not complicated by an asphysical element, the blood pressure falls as
the drug takes effect, and that in the case of chloroform the fall is
often quite considerable. Such a fall can be appreciated by the skilled
finger, but only by concentrating upon that examination a degree of
attention which necessarily detracts from the administrator’s available
energy for the observation of other signs which are of equal value, and
can be more rapidly and certainly appreciated and appraised.
It is nevertheless essential to assure oneself during the whole
progress of an anæsthesia that the circulation is in a satisfactory
condition. Two obvious guides to this are the colour of the patient’s
face and the force with which cut arteries spout. As regards the colour
in circulatory failure, one would naturally expect a pallid face, and
this indeed is the rule. It must not be forgotten, however, _that
cyanosis may sometimes be cardiac in origin_. Cases do sometimes occur
when a bluish tinge is seen on the lips, ears, and nostrils, apart from
any obvious cause of oxygen starvation. In these we may reasonably
suspect that the right heart is failing, and take measures accordingly.
Another valuable index to the state of the circulation is the “skin
reflex,” that is, the speed with which the circulation returns to an
area of the skin which has been pinched. The student should train his
eye by occasionally pinching the lobule of the patient’s ear and
observing first the white area so produced, and later the rate at
which, in a normal case, the healthy colour returns.
Abnormal Phenomena in Anæsthesia.
It is not intended to furnish here any account of matters more suitably
treated under the “Accidents of Anæsthesia,” which are fully described
in Chapter xvi., but merely to draw the attention of the student to
certain departures from the normal course of anæsthesia which are
encountered with varying frequency, to ascribe them as far as possible
to their true causation, and indicate methods of prevention.
The abnormalities fall into two classes, those connected with the
nervous and muscular systems, and those in which respiratory changes
are evident.
MOTOR AND NERVOUS SYSTEM.
_Clonus or tremor_ sometimes appears in one or more limbs, even the
trunk being affected in severe cases. Ether is practically the only
anæsthetic under which the tremor ever appears, and the condition is
often spoken of as “ether tremor.” It rarely appears in the female
subject, being almost limited to powerfully built young men. Coming
on towards the end of the second stage, it frequently persists in the
deepest of third stages, and in bad cases there is usually no option
but to change over to chloroform--always supposing that the tremor will
interfere with the work of the surgeon. If it will not, the condition
calls for no active treatment, since it is in itself not dangerous.
_Movements recalling to the observer the condition of athetosis seen
in the limbs of hemiplegics_ are occasionally seen in the anæsthetised
patient. The fingers of a hand may be slowly moved, or one or other
shoulder may be shrugged. The exact cause of these movements is
obscure. They occur in all types, both sexes, and at all ages; they are
not necessarily asphyxia though a trace of asphyxia seems sometimes
to conduce to them. They persist for some time after the third stage
has been entered, and ultimately disappear without any obvious cause
other than the passage of time. It is rare for them to continue more
than five or ten minutes after full anæsthesia has been induced. Their
practical importance lies purely in this, that the inexperienced
anæsthetist observing some muscular movements still persisting, may
take them as an infallible sign that anæsthesia is not complete, and
may deliberately take his patient to a deeper level. If in doubt, the
anæsthetist must, of course, consult all the other recognised guides,
such as the eye reflexes, but once he has seen these movements in a
case, and had demonstrated to him _their slow, rhythmical character_,
he is not likely to be misled on a future occasion.
_Muscular rigidity_ has been mentioned already in Chapter iii. When
it persists in a patient in whom other signs suggest that a full
anæsthesia has been produced, the anæsthetist will usually find that
attention to the air-way, and perhaps a whiff of oxygen, will remedy
the trouble.
Respiratory Abnormalities.
_Shallow breathing_ or even slight temporary arrests of
respiration arise frequently. During the induction stage they may be
due to:--
1. Apnœa or acapnia following voluntary excessive breathing.
2. Using morphia before chloroform.
At a later stage, it may be due to:--
1. Acapnia following excessive breathing excited reflexly from
the seat of operation.
2. Direct reflex inhibition of the respiratory centre.
An example of this is seen sometimes when the bladder is
over-distended by lotion.
3. Impending vomiting.
_Moist sounds_ not uncommonly appear. The student’s general knowledge
of medicine will enable him to decide whether the fluid is likely to
be in the pharynx, larynx, trachea, or bronchi. If in one of the first
two named, it will suffice to swab out the throat and encourage the
patient to cough. If, however, moisture is evidently present in the
trachea or bronchi, the condition is one calling for considerable care
and judgment. It arises more commonly with ether than with chloroform.
Much will depend upon how much longer the surgeon requires to finish
his operation. If only a few minutes more are required, nothing is
necessary but to cut down the amount of ether being given to the
minimum possible. If, however, the surgeon has still a good deal to do,
the safest thing is to withdraw the ether and substitute chloroform
or a mixture. Be it clearly understood, however, that such a change
over is not devoid of risk. If it is to be made, it must be done
early, before the patient is cyanosed and almost drowned in his own
secretion. In a neglected case where cyanosis has already appeared,
there will be no option but to interrupt the operation, empty the chest
by encouraging coughing, and to aid the process by compressing the
patient’s chest during expiration. Thereafter chloroform may be given,
but with the greatest care.
_Gasping and sighing_ are not common phenomena but when they occur,
call for close notice from the anæsthetist. Excluding, of course, such
occurrences in the first stage, before volitional control has been
lost, they may be _usually but not invariably ascribed to overdosage
or to the appearance of definite surgical shock_. Whenever they are
noticed, therefore, it behoves the administrator to overhaul the
patient thoroughly, to consult the eye reflexes, the skin reflex, and
the pulse, and not to rest until he is assured that there are no other
signals of danger to be found.
_Stertor and stridor._ The first of these is caused by flapping of the
soft palate. It is a noise low in pitch, resembling ordinary snoring.
Indicating as it does that the palatal and therefore probably other
muscles, are relaxed, it may if moderate in volume usually be taken as
a favourable sign. If it becomes very loud, however, the probability
is that the base of the tongue has fallen back; cyanosis will begin to
appear, but will immediately be remedied by pulling forward the jaw or
in extreme cases, using the tongue forceps.
_Stridor_ is a high-pitched sound produced by approximation of the
vocal cords. It has already been dealt with in Chapter iii.
False Anæsthesia.
This term has been applied to a condition often seen in children,
and occasionally in adults. It is almost limited to chloroform: the
author has never seen a genuine case when ether has been in use. It
appears very quickly after inhalation has begun: the muscles are
relaxed, the respirations quiet and regular, the conjunctival reflex
sluggish. A very marked feature is the excessive smallness of the
pupil. Obviously then, the condition much resembles a true third stage,
but if the operation be begun, the mistake will very rapidly be made
evident, for the patient will at once move and cry out. In essence, the
condition is simply one of ordinary sleep. It can be recognised by its
appearance after a period of inhalation too brief for the induction
of true anæsthesia, by the very small pupils and the lightness of the
respiration. It will be a waste of time to permit the condition to
continue, as the lightness of the respiration delays the taking in of
a dose of the anæsthetic sufficient to induce a proper third stage.
The remedy is simple,--rub the lips and face smartly with a towel or
the hand, when respiration will at once deepen and the pupil dilate.
Thereafter, the induction should proceed normally.
CHAPTER VI.
PREPARATION OF THE PATIENT.
For all but short anæsthesias conducted chiefly by nitrous oxide, the
intestinal tract of the patient must receive careful preparation. In
doing this, one must avoid excessive starvation and purgation, both of
which tend to increase shock.
We will suppose that the operation is timed for 10 a.m. on Tuesday
morning. On Monday morning the patient receives an aperient which
may be varied a little to suit his taste and habits. If he has no
preference, there is nothing better than an ounce of castor oil. During
the rest of Monday, he has a light diet: fish and milk pudding in the
middle of the day, a little soup at night. The aperient should operate
before 9 p.m. When that is over, the patient retires to bed. During the
day he may be allowed to move about his room a little, but should not
undertake any exertion.
If there be excessive nervousness, or a natural tendency to insomnia,
sulphonal gr. 15 or veronal gr. 8 may be given early in the evening, to
ensure a night’s rest.
About 6 a.m. on Tuesday morning, a large soap and water enema is given,
and when this has operated, a cup of tea or a little soup or Bovril may
be taken. Thereafter nothing should be given by mouth.
The early forenoon is the time of choice for any operation, but if
an afternoon time be of necessity chosen, the patient should not be
starved throughout the forenoon. A repetition of the early morning meal
may be allowed about 11 a.m.
In cases such as gastro-enterostomy, where the alimentary tract will be
opened, the preparation must be a little more stringent. It is usual
to allow no solids at all the day before. A saline enema may be given
an hour or two before operation, when the soap and water has been
evacuated.
Preliminary Hypodermic Medication.
This great improvement in anæsthesia was practised many years ago by
a few surgeons, but it was only when open ether assumed its present
position of pre-eminence that it was widely adopted.
The present routine is to give morphia gr. ⅙, atropine gr. ¹⁄₁₂₀ to
adult patients three quarters of an hour before operation. It has the
following _advantages_:--
(1) The nervous fears of the patient give place to a feeling of
bien-être.
(2) The secretions of saliva and of mucous from the respiratory
mucous membranes are limited.
(3) A little less inhalational anæsthetic is required.
(4) The after vomiting is lessened, and probably the liability
to inflammatory respiratory complications also reduced.
The _disadvantages_ can be met by proper care and dosage. They are as
follows:--
(1) Morphia _plus_ chloroform depresses the respiratory centre
at an early stage of anæsthesia. Respiration becomes infrequent
and shallow, and cyanosis appears before the patient is really
sufficiently anæsthetised for the purposes of the surgeon.
(2) The larger the dose of morphia, the more troublesome is this
premature failure of respiration.
_The moral_ is obvious: give the small doses above recommended and
induced with mixtures weak in chloroform, or better still with ether
only (see page 86).
Some years ago, before these facts were appreciated, there was a
fashion for giving very large doses of preliminary narcotics. The
combinations most favoured were as follows:--
SCOPOLAMINE-MORPHINE.
Scopolamine is a form of hyoscyamine and is itself a powerful narcotic.
Two or sometimes three doses of the mixed drugs were given at intervals
of an hour, the last half an hour before operation. Scopolamine gr.
¹⁄₂₀₀, morphia gr. ⅛ was the usual formula: some surgeons added a dose
of atropine or strychnine with the idea of stimulating the respiratory
centre.
The patients went to the operating or anæsthetising room so drowsy
that they were unaware of their surroundings, and afterwards had no
recollection of the actual beginning of the inhalation. So humane a
method naturally attracted a good deal of attention, but the serious
depression of the respiratory centre which seems inevitable in the
method has gradually caused it to disappear from the practice of
most surgeons and anæsthetists. At the present day, it is only to
be recommended in midwifery practice; to the drowsy semi-conscious
condition produced, the name of _Twilight Sleep_ has been given.
OMNOPON AND OMNOPON-SCOPOLAMINE.
Omnopon is composed of a mixture of several of the alkaloids derived
from opium; the makers claim that it produces less after malaise than
morphia alone. It may be given before anæsthesia in doses of ⅙–⅓ gr.,
either alone or combine with a small dose of scopolamine. It gives
quite good results if not pushed to excess.
HEROIN HYDROCHLORIDE
This comparatively modern sedative is used by some surgeons in
preference to morphia. A dose of ¹⁄₁₂ gr. is quite sufficient, three
quarters of an hour before operation. Atropine should always be
combined with it.
* * * * *
To young children, morphia should not be given, but atropine may be
given freely. A child of twelve months tolerates a dose of ¹⁄₂₀₀ gr.
quite well: one of six years, will take ¹⁄₁₅₀ gr.
In ages ranging from 12 years upwards, greatly reduced doses of morphia
may be given. No child under 15 years requires more than ¹⁄₁₂ gr. of
morphia at most.
CHAPTER VII.
NITROUS OXIDE.
Special Physiology.
Upon the nervous system, nitrous oxide acts like other anæsthetics,
but the stages of anæsthesia are passed through so rapidly that a
second stage can hardly be distinguished. It is rare for struggling or
excitement to be manifest, unless air or oxygen be admitted at the same
time, when the effect which led Humphrey Davy more than a century ago
to apply to nitrous oxide the name of “laughing gas” is very evident
indeed.
Upon the other systems of the body, nitrous oxide has little if any
effect in itself. The essential point to remember in connection with
nitrous oxide administered unmixed with air or oxygen is that there
is an _inevitable element of asphyxia_. The larger part of the
oxygen normally carried by the red blood corpuscles is eliminated
and replaced by N_{2}O: oxygen starvation is therefore of necessity
present. In other words, the “vicious circle of asphyxia” (_see_
Fig. 5) is entered, and muscular spasm is bound ultimately to appear.
Moreover, the blood pressure rises very materially as a result of the
lack of oxygen. That no harm results to the normal healthy patient
from this rise is due to the fact that the gas does not in itself
poison the heart muscle, which can therefore stand up to the extra
strain of working against higher resistance, so long as the process
is not carried to extremes. A heart muscle weakened by the action of
chloroform would give out at once if exposed to such a test.
Apparatus.
Nitrous oxide is supplied by the makers as a fluid condensed in iron
bottles or cylinders, and only becomes gaseous upon being released from
them. In passing from the fluid to the gaseous state, heat is of course
lost, and it will be noticed that the end of the cylinder which is in
use becomes rapidly crusted over with frost. Ice, moreover, forms in
the small channel at the head of a cylinder, and is apt from time to
time to block it.
The cylinders are of various sizes and designated after the numbers
of gallons of gas which they will supply: 25 is the smallest size, 50
or 100 are more usual; anything up to 500 is occasionally met with in
hospital practice. Moreover the cylinders are of two types, called
respectively _vertical_ (for use in the upright position), and
_angle_ for use in the horizontal position (_see_ Fig. 13).
[Illustration: FIG. 12.--Frame for adapting vertical
cylinders to foot use.]
[Illustration:
FIG. 13A. FIG. 13B.
Two types of N_{2}O cylinders.
A. Vertical (or ordinary). B. Angle.]
The cylinders are fixed in frames of various types of which examples
are seen in Figs. 13 and 14.
Upon each cylinder, of whatever size or type, will be found a label
stating its weight when full and empty, the difference representing
the weight of the contents when the bottle is full. For instance, in
the case of the 50-gallon cylinder the weight of its full charge is 15
ounces. Weighing the cylinder is the only certain means which we have
to estimate how much of the charge remains. The student will readily
appreciate therefore that once a cylinder has been used at all there
is always a risk of the supply of gas from it running out during an
administration. It is for this reason that cylinders are habitually
used in couples, one of which is always supposed to be quite full. To
this one it is well to attach a label marked “full,” and care must be
taken to replace at once a cylinder known to be empty. In this way we
always have upon the frame one cylinder partly and another entirely
full.
[Illustration: FIG. 14.--Complete N_{2}O apparatus,
showing twin cylinders, supply pipe, 2-gallon bag, 3-way tap,
and face-piece.]
By whatever makers the cylinder is supplied it will be found that the
thread upon the outlet pipe is the same, and the metal nipple figured
in Fig. 14 will fit it. To the distal end of the nipple, a rubber tube
is attached which leads to a rubber bag usually of 2 gallons capacity.
The remainder of the apparatus may be of several types.
Fig. 15 shows the ordinary _Barth three-way_ tap with facepiece;
the indicator on the tap has three possible positions designated on
the dial as “Air,” “Valves,” and “No Valves.” If the tap is pointed
backwards towards the bag at the position marked “air” the end of the
bag is closed and the patient is breathing air only. With the tap in
the middle position of “valves,” the inspiration of the patient will
draw gas from the bag, but the expiration closes the valve which is now
in operation at the orifice of the bag, and will open the expiratory
valve which conducts the expired air into the general atmosphere. In
the third position of “no valves” the patient breathes both in and out
of the bag.
[Illustration: FIG. 15.--Barth 3-way N_{2}O tap.]
[Illustration: FIG. 16.--Hewitt’s wide-bore gas
valves.]
Fig. 16 shows the Hewitt type of inhaler. The calibre of the orifices
through which respiration takes place is greater than in the Barth
three-way tap, and to that extent this type of valve is to be
preferred. Although differently arranged exactly the same possibilities
are present in it.
The _facepiece_ is sometimes made of celluloid with an inflatable
rubber edging. The object of this type of facepiece is that the
colour of the lips may be appreciated by the anæsthetist during the
administration. The preferable plan is to make the whole facepiece of
rubber with an inflatable border. Such a facepiece made by a good maker
will last many years, and is much more stable and reliable than its
celluloid competitor.
The Care of the Nitrous Oxide Apparatus.
This is a matter of considerable moment, particularly to those who do
not use their apparatus every day. After use, the valves, facepiece,
and bag should be disconnected from each other, all moisture wiped away
from the bright parts, and the bag hung up with its open end downwards,
and preferably in a warm room. If re-breathing has been extensively
practiced it is well to wash the bag out with some carbolic lotion
before hanging it up. The rubber valves in the valvepiece are liable
to lose their elasticity, particularly if kept in a cold place after
becoming damp. From time to time the valve piece should be taken to
pieces, the valves carefully dried in front of a warm fire and powdered
over with a little talc.
Administration.
Most commonly nitrous oxide is administered to a patient sitting in a
chair. Care should be taken that the respiration of the patient shall
not be obstructed by tight clothing round the throat or chest, and
that the head and neck are neither unduly flexed nor extended upon the
shoulders. The patient should not have any solid food for two hours
before the anæsthetic. At the last moment he should be instructed to
empty his bladder. Artificial dentures if present should be removed,
and, if the anæsthetic is being given for the purpose of the extraction
of a tooth, it will be necessary before applying the facepiece to
insert between the teeth a dental prop. (See Fig. 6.) Standing to the
left and slightly behind the patient the anæsthetist’s first step is to
secure good apposition between facepiece and face. This is best done by
working from above downwards: that is to say, secure first a good fit
at the bridge of the nose, and then approximate the remainder of the
rim of the facepiece to the cheeks and lower jaw. During this stage the
indicator of the tap is kept at “Air.”
Working with the left foot the administrator now opens the head of one
of the cylinders with the foot key. It is wise first to have loosened
this with a hand key, and leave it just “on the swing,” otherwise
one’s boots are apt to suffer! Gas is allowed to flow into the bag
until it is partially, but by no means tightly distended. The patient
is instructed to breathe naturally and easily, and during the whole
process the anæsthetist should converse with him in a quiet easy way.
The tap is now turned to “valves” and the patient begins to inspire
the gas, a supply of which is allowed to flow steadily from cylinder
into bag. After a few breaths of the gas, when the sensibilities
of the patient are a little dulled, it is wise to allow the gas to
flow a little more freely and to distend the bag. This exercises
upon the patient a slight _positive pressure_, which has been proved
both experimentally and practically to increase the rapidity of the
absorption.[1] The valves are left in operation for some thirty or
forty seconds, after which time the supply of gas should be cut off
and the tap be pushed over to the position of “no valves” for further
twenty seconds. This should be ample to secure full gas anæsthesia.
_The phenomena_ seen in nitrous oxide anæsthesia are so different from
those of any other that a few words must be said about them. Within a
few seconds of the inhalation beginning, the colour of the patient
shows evidence of the presence of the gas in his blood. The normal
complexion changes first to a dull pink, and very rapidly to the
definite blue of cyanosis. The _eye symptoms_ are of the utmost value.
Very early the pupil begins to dilate, and the eyeball tends during the
first twenty or thirty seconds to rotate as if the patient were looking
for some object in his field of vision. In full anæsthesia the eyeball,
however, comes to rest, usually pointed downwards. The pupil is widely
dilated, the conjunctival reflex is almost or even entirely abolished,
but the corneal reflex is still brisk. _The respiration_ tends to
become steadily deeper and more frequent, and in the later stages
stertor at least, if not stridor usually develops. _The muscles_ under
ordinary nitrous oxide anæsthesia are rarely entirely relaxed, but the
limbs hang motionless, and it is only if an attempt be made to move
them into some abnormal position, that one appreciates the persistence
of muscular tone.
A phenomenon peculiar to nitrous oxide anæsthesia is observed in its
deepest stage. Designated as _jactitation_, it consists in a tremor
beginning in the limbs, but spreading from them to the trunk if its
development is allowed to proceed. It is a finer movement than that
described under “ether tremor” (page 38), and wholly different in type
from the athetosis referred to on page 38. Jactitation is almost wholly
an asphyxial phenomenon, and is therefore definitely an indication
that the process of oxygen starvation has been carried as far as is
permissible.
_The signs of fully developed nitrous oxide anæsthesia_ then are:--
1. Deep regular snoring respirations.
2. Dilated pupils.
3. Rotation of the eyeball downwards.
4. Loss of conjunctival but persistence of corneal reflex.
5. A colour of the skin definitely blue, but not blackish blue.
6. The commencement of jactitations.
_The signs of overdose_ are:--
1. An enormously dilated pupil not re-acting to light.
2. Loss of corneal reflex.
3. A blackish blue colour.
4. Jactitations fully developed.
5. Failing respirations.
The final arrest of respiration in nitrous oxide anæsthesia is usually
painfully sudden. Upon the respiratory side the only warning is one or
two gasps, and even that is sometimes absent. The paralysed pupil and
the jactitations are the most useful signs of overdose.
The above, then, may be taken as an account of what one expects to see
in a normal gas anæsthesia during the induction stage. For the great
majority of cases, nitrous oxide is given for the purpose of rendering
painless the extraction of a tooth, and it is, in this large class of
case, the induction stage only which need be considered. It requires
only some fifty to sixty seconds to bring the patient to the stage
described under the heading “fully developed anæsthesia” and when that
has been attained, the mask may be removed and the operation begun.
From the moment of removal of the mask, however, it must be noted that
the patient begins to breathe fresh air and to eliminate the N_{2}O.
The period of anæsthesia available to the surgeon or dentist during
which he must perform the operation, is therefore very small. In thirty
seconds the patient has frequently recovered sufficiently to begin
to feel pain, and it is rare to secure more than forty-five or fifty
seconds by the use of a single dose of nitrous oxide.
Nitrous Oxide and Air.
If the nature of the operation does not necessitate the removal of the
mask from the face, it is possible to maintain nitrous oxide anæsthesia
for some considerable time. The exact length of that time varies a good
deal with two factors--the type of patient and the experience of the
administrator. Heavily built muscular patients are not easily dealt
with by prolonged gas anæsthesia (unless with admixture of oxygen as
explained in chapter viii.) Of far greater importance, however, is the
other factor. The student can easily be taught to give a single dose
of gas for the extraction of a tooth, or the momentary incision of an
abscess. He will, however, be wise to secure a good deal of practice in
that class of work before attempting to prolong gas anæsthesia for more
than a minute or two.
With reasonable skill and experience and the utmost care, it is,
however, perfectly possible to prolong nitrous oxide anæsthesia for
periods of five, ten, or even fifteen minutes in the average healthy
patient. As soon as the signs of full anæsthesia appear, the valve
tap is pushed back to “air” for the space of one inspiration and
one expiration, and then at once pushed back to “no valves.” By
this manœuvre, one inspiration of air is permitted to the patient,
whose colour at once shows amelioration, or at any rate no further
progression of cyanosis. The admission of air is repeated every third,
fourth, or at most fifth respiration. After the first minute or so
of this cycle of events, it is obvious that the contents of the bag
will be composed of a mixture of nitrous oxide, air, and CO_{2} in
proportions quite impossible to calculate. It is therefore best to
push the indicator to “valves,” and allow the bag to be emptied by the
suction of the patient’s inspirations. The cylinder head is then opened
by the turning of the foot-key, and the bag filled again with gas. The
cycle of “air” and “no valves” is then begun again for another minute
or so.
It must be understood that by this process, it is not to be expected
that an ideal anæsthesia can be produced. Some movement of the patient
will not improbably take place when sensitive structures are cut or
handled by the surgeon, and at no time will the muscles be entirely
relaxed. Such an anæsthesia is therefore only suitable for a limited
class of case, but does admirably for, say, opening an abscess,
exploring its interior, and removing from it a sequestrum or an easily
found foreign body. During his service in Macedonia the author had not
at his disposal any of the appliances later to be described under the
heading of nitrous oxide and oxygen, and found “gas and air” a most
useful form of anæsthesia for the requirements of military surgery as
seen in a Base Hospital, under active service conditions.
Contra-indications to the Use of Pure Nitrous Oxide Gas.
In the healthy subject, there is no safer anæsthetic than nitrous oxide
when administered properly and limited to its proper province.
From the account given of the physiological action of the gas it will,
however, be obvious to the student that in a limited class of case its
use is not permissible. Such cases fall into two categories.
_Firstly, cases in which an asphyxial element already exists will
have their condition greatly aggravated by the substitution of N_{2}O
for the oxygen in their blood._--Already caught in the vicious circle
of asphyxia, nitrous oxide would but push them deeper into the
vortex. Examples of such cases are patients suffering from tumours or
inflammatory swellings in the neck which are pressing upon the air
passages. In passing, one may note that it might be the desire of the
surgeon to submit an individual case falling into this group to the
operation of tracheotomy for the immediate relief of the condition. The
short space of time required for this little operation might well tempt
the unwary to choose nitrous oxide as the anæsthetic, and in point of
fact such an error of judgment has more than once been made with fatal
results.
_Secondly, no patient suffering from any condition which will be
aggravated by a sudden rise of blood pressure, should be submitted to
nitrous oxide undiluted by oxygen._--Examples of such conditions are
cases of _dilated right heart_ with weakened cardiac musculature.
Such hearts could not be expected to work against a peripheral
resistance suddenly raised, say, from 120 mm. of Hg, to 180 or even
200 mm.--figures well within the possible in deep gas anæsthesia.
Similarly, so great an increase of pressure would be dangerous
to a patient suffering from an _aneurysm_, or from _extensive
arterio-scelorosis_ with high blood pressure.
It will be noted that the above warnings are limited to the use of pure
nitrous oxide, that is, N_{2}O unmixed with oxygen. The extent to which
the dangers referred to can be met by the admixture of oxygen in the
manner to be described in the next chapter is largely a matter of the
skill and experience of the administrator.
Nasal Methods.
The object of using this route is to be able to continue the
administration throughout the period in which the dentist is doing his
work. The essentials of a suitable apparatus are:--
1. A malleable nosepiece which can be closely adapted to the
nose.
2. Two supply pipes from bag to nosepiece.
3. Some means of admitting air to the stream of gas.
4. A two-gallon bag.
5. A supply of gas.
6. A mouth cover with an expiratory valve only.
The patient is instructed to breathe in through the nose, but to
expire through the mouth. The gas is supplied under some pressure and
the mouth cover ensures that no air is inspired by that route. Some
patients find it easier to conduct both inspiration and expiration
through the nose, and for their benefit an expiratory valve is also
provided in the nosepiece. After unconsciousness has supervened, nearly
all patients begin to-and-fro nasal breathing. The mouth cover may then
be removed, and if it be desired to economise gas, the expiratory valve
in the nosepiece may be thrown out of action.
[Illustration: FIG. 17.--Ash’s Modification of
Paterson’s Nasal Gas
DESCRIPTION:--A--Nose-Cap Attachment with Stopcock for
Air and Gas, and with Inspiratory and Expiratory Valves
and Shutter. B--Nose-Cap. C--Sliding Clip on India-rubber
Tubings. D--Bifurcated Mount. E--Bag Mount. F--Gas Bag
Compressor. G--Gas Bag. H--India-rubber Tubing. MC--Mouth
Cover. This is fitted with an expiratory valve, and should
be used at the same time as the Nose-Cap. By using the two
together patients are more quickly anæsthetised than they
would be if only the Nose-Cap were used, and the Nitrous
Oxide is economised.]
Air must be admitted in limited quantity through the tap after
the first thirty seconds or so; by a judicious regulation of this
mechanism, anæsthesia may be prolonged for five or ten minutes.
Facility with nasal gas comes only after some considerable practice.
Fig. 17 shows Ash’s No. 3 Patented Nasal Inhaler, which admits of
Air or Gas being administered either by the Naso-Oral Method, or by
to-and-fro nasal breathing. _Air_ only is admitted when the Shutter A
is open and turned to the right as far as it will go. _Nitrous Oxide_
is admitted when the Shutter A is open and turned to the left as far
as it will go, and the patient will breathe it in-and-out through the
nose. _For the Nasal Oral Method_, close Shutter A and turn it to
the left as far as it will go. This will cause the patient to inhale
through the nose and exhale through the mouth.
Nasal attachments are provided with most of the gas-oxygen apparatuses
mentioned in the next chapter. With them good results can be obtained
with much greater ease.
For a more detailed account of nasal methods, the student is referred
to works devoted entirely to Dental Anæsthesia.
CHAPTER VIII.
NITROUS OXIDE AND OXYGEN.
The account given in the previous chapter of anæsthesia by nitrous
oxide and air will have convinced the student that it is a somewhat
inelegant method with a limited sphere of usefulness. The reason is
obvious. In atmospheric air, oxygen exists only in the proportion
of about one to four of nitrogen. To sustain life it is therefore
necessary to admit to the anæsthetic mixture an amount of air which
leaves too little room for the anæsthetic factor--nitrous oxide. If,
however, pure oxygen be used, the nitrous oxide is diluted to a much
less degree, and far better results are obtained.
The exact scope for gas-oxygen anæsthesia cannot at present be defined
with certainty. The work of Crile, and the experience of the war have
done much to enlarge it. We may say that the following are definite
indications for its use:--
(1) Minor operations lasting 5–15 minutes, particularly if
performed on out-patients.
(2) Operations of any variety upon the subjects of severe shock.
(3) Operations upon patients suffering from acute sepsis.
(4) Operations repeated upon the same subject at short intervals.
As regards (3) and (4), the lack of toxic properties in nitrous oxide
gas, and the rapidity with which it is eliminated, give it a tremendous
advantage over ether or chloroform. To men with shattered bones and
extensive damage to soft tissues, badly infected with sepsis, who
required repeated opening up of pockets, changing of gauze packs, etc.,
the advantage of gas-oxygen over ether was evident, and was easily
appreciated by the patients themselves during the late war.
There are, however, certain _drawbacks_ to the method which must be
appreciated--
(1) The necessary plant is heavy, bulky, and costly; it cannot
be easily transported.
(2) The running cost is high as compared with ether or
chloroform.
(3) It has been said by some that gas-oxygen can only be given
by an expert. That is a statement too extreme, in the author’s
opinion. Certainly, of all anæsthetics it is the most difficult
to give successfully. Adequate study and proper teaching by an
expert are required, but given these two helps, any one can soon
learn to administer gas-oxygen for minor surgery. Considerably
more experience is, however, necessary before the beginner
should give it for an abdominal section.
Apparatus.
A good gas-oxygen apparatus is necessarily rather complicated. The
machines in the market are numerous, and of the most diverse external
appearance. Certain broad principles, however, underlie all the
machines, and it is to be hoped that some one of them will before long
become practically the standard. Once that is effected, hospitals and
nursing homes could be expected to provide them. So long as every
anæsthetist asks for a different machine, they certainly never will do.
A good machine must provide means for the following:--
(1) _An even flow_ of both gases under perfect control.
(2) _A percentage of Oxygen_ in the mixture rising at the
will of the administrator from 2 to 15 or 20.[2] To meet this
requirement it is not necessary that any indicator should be
provided which shows with mathematical precision what percentage
of oxygen is being given. The colour of the patient tells us at
once if too much or too little oxygen is being supplied, and all
we need in the apparatus is some mechanism whereby we can tell
approximately to what extent we are increasing or decreasing the
percentage.
(3) _Positive Pressure._--If the pressure at which the gases are
supplied to the patient can be raised a little above that of
the ordinary atmosphere, absorption is increased and a deeper
anæsthesia produced. In the author’s view, this is an essential
point in a good instrument.
(4) _Re-breathing._--To supply the whole volume of gases
required for inspiration during a long operation is costly and
quite unnecessary. Yet that is what is being done if the whole
administration is conducted upon the “valvular” principle.
Moreover, a prolonged inhalation upon the valves tends to remove
a great deal of CO_{2} from the patient’s blood and tissues
(_see_ Chap. IV.). Periods of partial or complete re-breathing
do much to deepen respiration, and reduce the cost of the
anæsthetic.
(5) _Warming the Gases._--While not essential, this is certainly
an advantage.
(6) _Addition of Ether Vapour to the mixture._--Gas-oxygen
even well given is hardly capable of reducing to quiescence
very robust people, unless the oxygen percentage is kept to an
undesirably low level. The merest trace of ether vapour as an
adjunct is a great assistance during the stages of the operation
where very sensitive structures such as the parietal peritoneum
are being handled. The more experienced the anæsthetist, the
less will he require such assistance.
Hewitt’s Apparatus.
This, with the exception of one designed by Dr Guy and the author,
and described on page 130, is the only machine with any pretence to
portability by hand. It does not satisfy all the requirements above
referred to, but the fact that it was the first practicable means
introduced in this country to give gas-oxygen entitles it to full
description. (_See_ Fig. 18.)
[Illustration: FIG. 18.--Hewitt’s gas oxygen
apparatus.]
Essentially it consists of the following:--
(1) A supply of nitrous oxide and oxygen in separate cylinders.
Hewitt’s own stand held two of nitrous oxide and one of
oxygen.[3]
(2) Rubber pipes of supply for each of the two gases. For
convenience, it is sometimes arranged that one of these shall
run inside the other.
(3) Two 2-gallon bags. Nitrous oxide is led into the one, oxygen
into the other. The mouth of _each_ bag is guarded by an
inspiratory valve.
(4) The mixing chamber. Upon the surface of this are marked
successively: “Air,” “N_{2}O,” “O_{2}, 1 2 3 4 5 6 7 8 9 10.”
As the indicator is pushed from “air” to “N_{2}O,” the patient
begins to inhale nitrous oxide only, but as it travels into the
numerals 1, 2, etc., a proportion of oxygen is added.
Immediately below the mixing chamber is the _expiratory valve_.
(5) Lastly, there is the _facepiece_, identical with that used
for pure nitrous oxide.
It would be fallacious to suppose that the numerals 2, etc., on the
dial represent accurately the percentage of oxygen yielded by the
instrument when the indicator points to one of these figures, nor
did Hewitt ever make such a claim. What the figures do represent is
a number of holes in the wall of the mixing chamber, opposite to the
aperture from the oxygen bag, which are uncovered one by one as the
indicator moves over. The amount of oxygen which enters into the mixing
chamber is regulated by the number of these holes uncovered, and also
by the tension of the oxygen bag. If the figure on the dial is to be
even a rough index of the actual percentage of oxygen present in the
mixture, it is necessary to keep the tension reasonably constant,
_i.e._ to regulate the flow of oxygen from the cylinder by manipulation
of the foot key. In a brief administration for, say, a dental case,
this is not necessary. It is sufficient to fill the oxygen bag once,
and then turn off the supply. If, however, a long administration is
required, a constant flow of oxygen of just the requisite amount must
be secured.
Administration.
Put the lever at “air,” and fill up each bag to an equal and moderate
degree of distention. Adapt the facepiece accurately to the patient’s
face, and then push the lever to “N_{2}O”. After a few inhalations,
move to 2 of oxygen; regulate the flow of nitrous oxide from the
cylinder so that the N_{2}O bag remains slightly distended. Gradually
move the indicator along the numerals until the figure 6 or 8 is
reached at the end of about a minute or a minute and a half. Women and
children require more oxygen than men. The former are easily cyanosed;
if the latter are fed too generously with oxygen, they are apt to
become excited. Take as your guide to the amount of oxygen required the
colour of the patient, the type of respiration, and the size of the
pupil.
The _colour_ aimed at can only be learnt by experience, but is best
described as a dull pink.
_The Type of Respiration._--Too little oxygen leads to stertor and even
stridor; too much oxygen, to a light almost noiseless respiration,
which to the experienced ear is the certain precursor of a stage of
excitement. Such a stage is clear evidence of too much oxygen having
been given.
_The pupil_ should not be dilated to anything like the degree seen with
undiluted nitrous oxide. A moderate distention only is to be desired.
_Full Anæsthesia_ should be reached in 100–120 seconds. It is marked
by:--
(1) Dull pink complexion; (2) full respiratory movements with
a stertor not exceeding that of gentle snoring; (3) eyeballs
rotated downwards; (4) moderately dilated pupils; (5) loss of
conjunctival reflex; (6) corneal reflex present but not very
active.
If the object be the removal of a tooth, the mask may now be removed,
and the dentist may rely upon a period of anæsthesia somewhat longer
than that furnished by pure nitrous oxide. He ought to secure
approximately one minute in which to do his work.
Anæsthesia by this apparatus may however be prolonged for an
indefinite time if desired. In order to maintain the patient in the
condition described above, it will be necessary gradually to increase
the supply of oxygen. For this purpose Hewitt added to his mixing
chamber a supplementary oxygen supply giving 10 or 20 volumes of
oxygen. As a matter of fact, all the necessary supply can be got
through the original ten holes _if the tension in the oxygen bag
be increased_. The regulation of all this requires, of course,
considerable practice and experience.
The signs upon which we rely for warning that the supply of oxygen is
insufficient to keep the patient safe, are chiefly the colour of the
face, which must not pass from dull pink to blue, and the size of the
pupil.
[Illustration: FIG. 19.--Diagrams to illustrate
action of (A) Hewitt (B) Teter gas oxygen apparatus. Note
that in A the mouths of both bags are guarded by valves of
inspiration, while in B the oxygen bag only possesses it.]
Deficiencies of Hewitt’s Apparatus.
These are chiefly two:--
(1) There is no means of producing _positive pressure_. Any
attempt to distend the nitrous oxide bag beyond a certain point
simply leads to escape of the gas through the mixing chamber and
out of the expiratory valve even during inspiration. To this
defect especially must we attribute the fact that an anæsthesia
deep enough for abdominal section is difficult to secure with
the Hewitt instrument.
(2) There is no means of securing _re-breathing_. The whole
administration must of necessity be conducted “upon the valves.”
This latter fault is remedied by the modification introduced by
_Burns_, who took away the inspiratory valve from the mouth of
the N_{2}O bag, and fitted a cap over the expiratory valve which
could be rotated so as to throw the valve out of action. The
author first met this modification at a Base Hospital in France,
and found it a great improvement upon the original instrument.
It is, however, only an imperfect attempt to adopt Teter’s chief
principle.
The Teter and Allied Machines.
The rapid spread of nitrous oxide and oxygen anæsthesia in the
U.S.A. brought forward a number of machines of which Teter’s was the
forerunner; the other well-known machine of the group is the Clarke.
They differ in principle from the Hewitt apparatus in that they permit
re-breathing and the use of positive pressure. Diagrammatically, the
two are contrasted in Fig. 19.
[Illustration: FIG. 20.--Details of the Clarke
Expiratory Valve. In the position of the lever marked “open”
the valve lifts easily and widely, and the breathing will
be purely valvular: in the position marked “half open,”
the valve lift is diminished, and the breathing is partly
valvular, partly to-and-fro. In the position “closed”
re-breathing only is possible.]
The key to Teter’s advance is his removal of the inspiratory valve from
the mouth of the nitrous oxide bag, and his substitution for Hewitt’s
rubber expiratory valve, of a _rigid_ valve, the lift of which
can be diminished or entirely abolished, at will (_see_ Fig.
20). By damming, as it were, the flow from the expiratory valve, the
administrator can oblige the patient to practise a certain amount of
re-breathing, and, if he keeps up a free flow of the gases, he can
develop a pressure in the nitrous oxide bag definitely exceeding that
of the atmosphere.
Teter also introduced into his apparatus a means to warm the gases, and
to add a little ether vapour to the mixture when required.
[Illustration: FIG. 21.--The Clark gas oxygen
machine.]
The Clarke machine is similar in principle to the Teter, but makes a
strong point of the intimate mixture of the two gases produced in the
mixing chamber which occupies the centre of the apparatus (Fig. 21).
In both these machines, it will be observed, the two bags for N_{2}O
and O_{2} respectively are attached to the stand, and the mixed gases
are led to the patient by a pipe of wide bore. When re-breathing
occurs, it must therefore be up and down this pipe, but the width of
the bore seems to obviate any disadvantage which theoretically might be
expected from this form of respiration.
[Illustration: FIG. 22.--Marshall’s sight-feed
gas-oxygen apparatus. Of the two glass bottles the one to the
left is the sight-feed, that to the right the ether chamber.]
In the experience of the author and of many other anæsthetists, very
good results can be obtained from either of these machines.
Sight Feed Machine.
In the author’s opinion, machines based upon this principle are likely
to take a prominent place in the future of gas-oxygen. Fig. 22
explains the simple mechanism. Each gas is led through a tube dipping
into water contained in the sight feed mixing chamber. The ends of
the pipes are open, and on the sides of each pipe also are a number
of holes. If the pressure at which either gas is delivered is small,
bubbles will be seen ascending towards the surface of the water from
the upper holes only. The greater the pressure, the further down the
pipe does the gas carry before all of it escapes through a hole, and
one can therefore get an accurate estimate of the pressure from the
number of holes through which the bubbles are seen escaping.
Upon the surface of the water, the two gases meet and enter into
mixture and are conveyed away by the third pipe which, of course, does
not dip into the water.
Once the eye of the anæsthetist is trained to its use, this is a very
simple means of gauging the relative proportions of oxygen and nitrous
oxide which are being delivered, and manipulation of the cylinder heads
combined with visual inspection of the sight feed enable one to strike
the right proportions very easily. The nitrous oxide is usually kept at
a constant pressure sufficient to ensure bubbles, not only from all the
side holes, but also a few from the open end of the tube. The oxygen
pressure is begun at the point where there is a little bubbling from
the top hole only, and is gradually increased until there is a full
supply from two holes, occasionally a little even from a third.
Messrs Coxeter have recently brought out two sight feed machines
designed by Mr Leonard Boyle and Dr Geoffrey Marshall, of which the
latter is shown in Fig. 22. This apparatus may be put up in either
portable form or a larger type for use in hospitals. An ether chamber
is provided for use when necessary in either type.
As originally introduced, the remainder of the apparatus consisted
simply of an ordinary two gallon bag, Barth 3-way tap, and rubber
facepiece. With such an appliance, it is not possible to secure
“positive pressure, a point which the author brought to the notice
of the makers. Messrs Coxeter are willing to supply a facepiece and
expiratory valve which obviate this defect, being supplied with a mica
expiratory valve the lift of which can be controlled. There should be
no inspiratory valve.
Administration of Gas-oxygen for the purposes of Major Surgery.
The patient is prepared with the same scrupulous care as if ether
or chloroform is to be administered. Half an hour before operation,
morphia gr. ⅙ and atropine gr. ¹⁄₁₀₀ are given hypodermically. The
anæsthetist before beginning administration, must look over the
apparatus most carefully and satisfy himself that every part of it is
in perfect order, and that a sufficient supply of both gases is at hand.
The inhalation is begun by the use of nitrous oxide alone, given “on
the valves,” and at no great pressure. After a few breaths, oxygen
is added very guardedly, the proportion being steadily raised during
the first two minutes: after that point, a further increase will not
be necessary until several more minutes have elapsed. The pressure at
which the mixture is being given is also steadily increased and should
reach the maximum permissible within a few minutes. A useful plan
is to allow the flow of gases to remain constant, but to close the
expiratory valve at frequent intervals for about forty to sixty seconds
at a time. During this period of complete re-breathing the tension in
the supplying bag will of course rise, falling again slightly when the
expiratory valve is allowed once more to come into action. As soon as
the tension falls appreciably, the valve is again closed down.
It is wise, particularly in one’s early days, to give a trace of ether
vapour during the latter part of the induction stage, and to maintain
it until the operation is well under way. Once the anæsthetist is
satisfied that the narcosis is proving deep enough for the purposes
of the operation, the ether may be shut off and will probably not be
required again.
Remember that _depth_ of anæsthesia can be secured in three ways--(1)
cutting down the oxygen percentage; (2) increasing the tension of
the mixed gases; (3) adding a little ether. Of these, No. 1 is most
undesirable, and if carried to the least excess over a period of more
than a minute or two may lead to an accident. No. 3 is the means for
the beginner to rely upon, until he learns the judicious and skilful
use of No 2. The anæsthetist who is learning the method of anæsthesing
must resolve that nothing shall tempt him to overstep the stage of dull
pink colour, and moderate pupils. If with gas-oxygen alone, he cannot
get a satisfactory anæsthesia without resorting to oxygen starvation,
let him not be ashamed to turn on his ether.
Abdominal relaxation sufficiently complete to permit the surgeon to
explore the abdominal cavity with ease, is not readily secured by
gas-oxygen in a patient of robust type. Fortunately, it is the weakly
or the severely shocked who really _need_ this form of anæsthesia, and
in them abdominal relaxation is fairly easily obtained.
Professor Crile, as has already been explained, does not rely upon
the inhalational anæsthetic alone. He infiltrates each layer of the
parietes with novocain, thus producing a local anæsthesia. If this
method be faithfully carried out by the surgeon, a most complete
relaxation of the muscles can be secured.
CHAPTER IX.
ETHER.
The drug commonly known as ether and otherwise described as ethylic
ether or sulphuric ether, has a chemical formula (C_{2}H_{5})_{2}O.
It is a transparent colourless fluid with a specific gravity of ·720
to ·723. A brand much used in the States has an S.G. of ·713 only, a
point which is greatly emphasised by its supporters, who claim that it
volatises quicker and therefore is more powerful in action. The author
has in actual practise not found much difference between this brand and
any good British one.
Ether is highly inflammable and volatilises readily at ordinary
room temperatures. Its boiling point is 96° to 98° Fahr. Whether
evaporating from a fabric such as gauze, or from bulk in a jar, ether
cools very rapidly, and the fall in temperature soon reduces the
ease of its volatisation. This point is of some practical importance
in anæsthetics, and some years ago the author made a number of
observations, hitherto unpublished, with a view of ascertaining some
definite facts in this connection. His results will be found in
Appendix I.
_Ether vapour_ is heavy--two and a half times heavier than air. It
therefore tends in a room to flow towards the floor, and to remain
for some time unmixed with the general atmosphere. Since it is highly
explosive, this constitutes a definite danger if any naked light or
open fire is present. Everyone who handles ether should bear in mind
these physical peculiarities of its vapour.
Ether is affected by prolonged exposure to bright sunlight, and also by
prolonged bubbling through it of air, nitrous oxide, or oxygen. Ether
which has been subjected to any of these measures should be inspected
before being put back into reserve, and if any brown discoloration
is noticed, it should either be sent to the hospital laboratory for
redistillation, or presented to the theatre sister for use as a
cleaning agent. Such contributions are always gratefully received.
Most of the ordinary impurities of ether are acid in reaction, while
ether itself is absolutely neutral. Any specimen which turns litmus
paper red should be sent to the laboratory for examination.
Sources of Supply.
Ethylic alcohol may be prepared either from ethyl alcohol or from
methylated spirits. In the former case it carries, however, the cost
of the duty imposed upon potable spirit, and since perfectly good
anæsthetic ether can be prepared from the latter source, it is waste of
money to use the more expensive article.
Physiology.
Ether acts upon the nervous system like other anæsthetics: as compared
with chloroform, however, the stage of excitation of each centre
before its paralysis is apt to be marked. There is, therefore, in some
subjects, a greater tendency to struggle; healthy subjects properly
handled do not show much evidence of irritation of the cerebrum. All,
however, show some evidence of stimulation of the respiratory centre,
which is not prolonged. _Prolonged deep and rapid respiration under
ether is due to other causes than the action of the drug itself._ It
is of course seen in “closed ether,” but the active agent is excess of
CO_{2}, not ether.
The working margin of safety in ether, _i.e._ the stage between loss of
spinal reflexes and the poisoning of respiratory centre is much wider
than in chloroform.
Some experiments of Waller made many years ago showed that upon nerve
tissue, ether acts much less powerfully than chloroform: in the
proportion, he found, of one to seven or eight. These laboratory
results have received entire confirmation by later workers who have
estimated the actual vapour strength required of either drug to produce
or maintain anæsthesia. Roughly, to induce anæsthesia, we require 2 per
cent. chloroform, or 16 to 18 per cent. of ether (_see_ Appendix II.).
The Circulation.
The first effect of ether is a temporary stimulation of the heart,
which beats more rapidly and more strongly, thus raising the blood
pressure. This effect is not very prolonged; like all other drug
stimulation, it is followed by depression. In the healthy subject
properly anæsthetised, such depression is very moderate in degree, and
in a normal administration it is probable that the heart, after the
first few minutes, is acting very much at its normal speed and force.
Ether is, however, a marked vaso-dilator, and the net result upon blood
pressure is a slight fall after the first few minutes.
If the method in use is “closed,” the pressure remains slightly raised
for some considerable time, usually throughout the administration. The
slight anoxaemia induces a vaso-constriction; and the CO_{2} excess,
in the view of Henderson (_see_ page 10), maintains a good return of
venous blood to the heart and a satisfactory cardiac output. For a note
of certain blood changes resulting from ether and other anæsthetics
(_see_ Appendix III.).
Respiratory System.
In addition to the effect upon the medullary centre already referred
to, ether effects the respiratory tract more profoundly than other
anæsthetics. The mucous membranes are irritated, and in some cases
there is a great outpouring of mucous. Though usually limited to the
upper part of the tract (nose, pharynx, and trachea), the irritation
sometimes extends deeply into the chest, affecting even the small
bronchioles. These unpleasant effects of ether are in the great
majority of cases, quite transient: after the first ten minutes no
addition to the secretions is noticed. In a minority, however, the
effect persists, the whole chest is filled with moist sounds, and
persistence with the drug is impossible.
_The kidneys_ are always slightly irritated by ether, and if they
are or recently have been subject to inflammatory disease, a very acute
exacerbation is apt to follow the use of the drug. In the healthy
kidney this is not to be feared, nor does it seem to be an appreciable
danger where one kidney is sound, even if the other is the seat of
gross organic disease necessitating its drainage or removal.
[Illustration: FIG. 23.--Clover’s ether inhaler, with nitrous
oxide attachment.]
Methods of Administration.
Many methods have been tried, but those which at present hold the field
are--
(1) Closed Ether.
(2) Open Ether, more properly called the Perhalation Method.
(3) The “Vapour” Method.
(4) The Rectal Method (Gwathmey’s oil-ether).
(5) The Intratracheal Method, described separately in Chapter
X.
[Illustration: FIG. 24.--Diagram of a vertical section through
the middle of Clover’s Inhaler. A. shows the ether dome; B.
Central tube removed from apparatus]
(1) Closed Ether.
The two inhalers originally brought out for this were Clover’s in
London, and Ormsby’s in Dublin. At a later date Hewitt’s “wide bore”
modification of the Clover was introduced.
(_a_) _The Clover instrument_ (see Fig. 23)[4] consists of a
face-piece, a dome-shaped ether chamber, and a one-gallon bag, usually
attached to the top of the ether chamber by a =T=-shaped tube. The
details of the method by which the amount of ether inhaled by the
patient is graduated are best appreciated by unscrewing the milled
head at the top of the dome, and withdrawing the tube which runs
through it (_see_ Fig. 24). In the tube will be found two slots, one
about half an inch above the other, and each extending for half the
circumference of the tube. Between these two slots the tube is divided
by a diaphragm. In any case, therefore, air passing up or down the tube
must pass in and out of these slots.
Now turn to the tubular space left in the dome piece, and examine
visually and with the finger its interior. On the one side of its
middle will be found two slots leading into the circular ether chamber
which occupies a large part of the dome. On the other side will be
found a small cavity, as deep from above downwards as the two slots
combined, but _not_ communicating with the ether chamber. It is obvious
that with the tube inside, if this cavity is opposite the slots in
the tube, air will pass up the tube out of one slot and back into the
other, without coming into contact with the ether at all. If on the
other hand the slots in the tube are opposite the slots in the ether
chamber, the air passes over the surface of the contained ether, and
volatises some of it.
Intermediate positions of the tube give a condition where part only
of the air passes over the ether. The indicator attached to the tube,
combined with the figuring “O, one, two, three, full,” to be found
on the outside of the base of the dome, shows at any moment what
proportion of the air is passing into the ether chamber.
To use the instrument, fill the metal measure provided with ether,
withdraw the stopper from the ether chamber, and pour in the ounce
and a half of ether which the measure contains. Replace the stopper,
and blow through the tube to expel any ether vapour which may have
appeared in it. Leave the rubber bag at first unattached: the patient
will feel more comfortable if during the first minute the top of the
tube is open. With the indicator at 0 adapt the face-piece to the face
and allow the patient to breathe up and down the tube. By rotating
the dome, ether is then gradually turned on, until the figure two
is reached in the first minute. The indicator is then slipped back
nearly to zero for a second, and the rubber bag slipped on during
an _expiration_: it must be moderately inflated to supply the
requisite volume of air for respiration.
[Illustration: FIG. 25.--Hewitt’s wide-bore ether
inhaler.]
The rotation of the dome is again begun and the indicator is made to
travel away from the zero, until at the end of about five minutes, it
reaches “full.” After the first few minutes, it will be necessary to
give an occasional breath of fresh air, otherwise an undesirable degree
of cyanosis will result, but it must be done with great discretion, or
struggling will ensue. At the end of about five minutes, anæsthesia
should be fully established. A little extra ether is then poured
into the chamber, the indicator pushed back to about “two” and the
administration continued. One breath of fresh air is given in every
three or four. Spells may be given with the bag off altogether, but
during such periods the indicator will require to be advanced a little,
and refills of ether provided more frequently than would be necessary
if the bag were on.
Hewitt’s-wide-bore.
The principle of this is identical with that of the Clover, but the
channels being wider, there is less mechanical interference with the
ingress and egress of air. The actual construction differs also, in
that to turn on the ether, instead of rotating the dome, one moves the
indicator (_see_ Fig. 25). The instrument certainly gives results
a little better than those obtainable by the Clover, but it is heavier,
and rather more bulky.
Ormsby’s Inhaler (_See_ Fig. 26).
This consists of a facepiece, a cage made of wire or thin steel slips
and containing a sponge; and lastly, a one gallon bag which fits
over the cage. In the face-piece is an air vent, which can be either
entirely closed, partially or entirely opened.
[Illustration: FIG. 26.--Ormsby’s Inhaler. The cage
for the sponge does not show in the figure, it projects
upwards from the bag-mount, and is therefore enclosed in the
bag.]
To use the instrument, take out the sponge and warm it either by
wringing it out of hot water, or better by leaving it a few minutes on
the top of a hot steriliser. Push it back into the cage, open the air
vent fully, and holding the inhaler upside down, pour on to the sponge
a measure full (about half an ounce) of ether. Tell the patient to
inhale deeply, and then catch the resulting expiration in the bag by
quickly adapting the facepiece to the face at the appropriate second.
After a few seconds, begin to close the air vent, when it will be
found that the bag begins to wax and wane with each expiration and
inspiration respectively. After the first three minutes, the inhaler
must be removed, more ether poured in, the air vent opened again
partially, and the inhaler again applied to the face. After full
anæsthesia is induced, the air vent may constantly be left partially
open.
_N.B._--It must be observed that the air vent is not valved: it is
merely an opening through which part of the respired air may pass in
and out without going near the ether sponge.
In actual practice, the induction stage of closed ether is almost
invariably assisted by using either nitrous oxide, or a small dose of
ethyl chloride as a preliminary: these methods are described in Chapter
XV.
The question now arises, what _scope_ is to be assigned in modern
anæsthesia, to closed-ether methods. Formerly a large proportion of
anæsthesias, long or short, were conducted by the closed method, and
while the greater number of anæsthetists no longer utilise them to the
same extent as formerly, they may still be regarded as of the utmost
value in a limited class of cases. They are speedy in action, powerful
enough to overcome the most refractory patient, and with reasonable
skill very safe. On the other hand, the anæsthesia obtained is not
of the most desirable type. There is a great deal of salivation and
mucous secretion from the respiratory mucous membranes; the respiratory
movements are deeper than in open methods, from the excess of CO_{2}
present in the blood, and this leads to a good deal of heaving of
the abdominal wall, which may be most troublesome to the surgeon
if he is opening or closing that cavity. Moreover, after their use
more headache, malaise, and vomiting occur than after open-ether, and
perhaps a little more tendency to bronchitis or pneumonia. For these
reasons, many anæsthetists and surgeons now object to their use in
abdominal surgery, though some still adhere to them for the induction
stage, passing to the open method when the patient is once well under.
(2) Open Ether.
As already explained the strictly accurate term for this is
Perhalational Ether, but so cumbersome a terminology stands small
chance of general acceptance.
Apparatus.
The essential points in a proper outfit have already been explained
(_see_ page 28) and are all well met by the mask and ether dropper
introduced by Mr Bellamy Gardner (_see_ Fig. 27). The mask is covered
with from twelve to sixteen layers of gauze, and lies on the gauze
ring, shown in the Fig. 28A, which completes the fit between face and
facepiece. The dropper fits into the ordinary six ounce dispensary
bottle: the long arm dips into the ether, the short one allows air
to enter the bottle to replace the ether used. A dropper can also be
improvised by using a cork with slots cut at each side and with
a gauze or wool wick inserted along one of these. The author finds
these uncertain in their action, however: with Gardner’s dropper, a
steady flow of _drops_ of ether slow or fast as required, can always be
obtained once the student has acquired the knack of using the appliance.
[Illustration: FIG. 27.--Bellamy Gardner’s (A) open ether
mask; (B) ether dropper.]
[Illustration: FIG. 28.
_A._--Open ether. Ready to begin.
_B._--Open ether. Condensing towel in position.]
[Illustration: FIG. 28.
_C._--Open ether. Correct method of holding mouth and jaw.
_D._--Open ether. Alternative method of holding mask.
The towel and gauze have been removed so as to show the
tilting of the mask which this method is liable to cause.]
To Mr Bellamy Gardner’s outfit, the author adds a folded towel, pinned
at one corner, so as to form a short cone. The base of this cone
embraces the mask and face; through its upper apperture the anæsthetic
is dropped on to the mask. The cone can be rotated into the position
most convenient for this purpose in any given position of the patient’s
head (Fig. 28).
Problems of the Induction Period.
Open-ether is not a powerful anæsthetic, just not powerful enough for
one to be sure that one can induce full anæsthesia with it alone, in a
powerful subject. The reason for this is shown in Appendix II, and may
be here condensed by explaining that some 18 per cent. to 20 per cent.
of ether vapour is required to induce anæsthesia, while it is not easy
to get more than 14 per cent. off an open mask. How is this situation
to be met?
Reference has already been made to one solution of the problem. _A
closed ether method may be used for induction_, and this practice is
widely used. The author does not often adopt this course, fearing that
the undesirable features of closed ether may persist even after the
change to an open method has been made.
Another possibility even more widely favoured is to use _chloroform as
the inducing agent_, and only to turn to ether when full anæsthesia
is obtained. To this plan the author is strongly opposed. It exposes
the patient to the risks of the induction stage of chloroform which
are much greater than those of the later stages. Moreover, to develop
the full advantages of open-ether, a preliminary hypodermic of morphia
is essential, and the drawbacks of chloroform _plus_ morphia are
elsewhere mentioned (page 43).
The use of a _mixture of chloroform two parts, ether three parts_,
presents the same disadvantage, but in a degree so much smaller that
in powerful or alcoholic patients, the author believes this to be the
method of choice (_see_ Chapter xiv.).
_Dr Silk_ has recently suggested another plan. He has sought to make
open-ether easy for the non-expert with a view of encouraging the
wider use of so valuable a method. For this purpose he advocates the
admixture of one part of chloroform in thirty-two of ether (a dram of
chloroform in four ounces of ether). This is to be given in exactly the
same way as perhalational ether, and will, Silk says, give a type of
anæsthesia, and a degree of safety, identical with those of pure ether.
The author’s experience with Silk’s mixture is too limited to enable
him to offer any opinion upon its merits.
Lastly, there remains the plan of using _ether as the main inducing
agent_, but assisting its action by the intermittent and most guarded
addition of small quantities of C_{2}E_{3} mixture. This is the
author’s “stock” method; but in teaching it to students, too much
emphasis cannot be laid upon the small quantities of chloroform mixture
required or _permissible_. _As a consequence of the perhalational
method here advocated, every drop of chloroform which appears on the
mask will when volatilised, give a very much higher percentage of
CHCL_{3} vapour in the inspired air, than the same quantity exhibited
on the ordinary open chloroform mask._ Once the student has grasped
this essential fact, ordinary care and intelligence will enable him to
guard against a danger which is only existent if unappreciated.
The Administration.
For many of the hints given in this section the author is indebted to
Dr W. J. Ferguson of New York, and Dr Hornabrook of Melbourne.
Success in inducing with open-ether is attained only by attention to a
number of small details. The student who thinks that some of these are
too trifling for his notice is usually the man who informs you that
induction by open-ether is impossible, the fact really being that he
has not taken the trouble to learn, or has never had proper tuition.
The following are the points demanding attention:--
1. Always give a dose of morph-atropine or other narcotic, half
to three-quarters of an hour beforehand.
2. See that the patient is comfortable on the table. Prop up his
head and shoulders a little with pillows. In powerful subjects
Hornabrook tilts the whole table down at the foot-end, for a few
degrees.
3. Adhere strictly to perhalation and to the drop method. You
will never induce with open-ether if the whole volume of the
respired air does not pass through the gauze.
4. Chat to the patient as long as consciousness can possibly
persist. Tell him he is doing very well. Don’t shout complicated
instructions at him as to how to breathe: it annoys and muddles
him.
5. When the gauze ring and the mask are in position, allow one
or two drops of ether to fall on the mask, then pause: in a few
seconds the mild ether vapour so formed will soothe the upper
respiratory tract, and prepare it for the stronger vapours yet
to come. This does not waste time--it saves it.
6. When the administration is again begun, attend closely to
the rate of dropping. At first not more than one drop in three
or four seconds is wanted. The full rate of dropping cannot be
attained for at least ninety seconds.
7. Give no mixture for the first ninety seconds; thereafter some
five to ten drops every half minute or every twenty seconds
according to type of patient. Have the mixture bottle handy so
that no time is wasted in changing bottles. Stop the addition of
mixture as soon as full anæsthesia is attained.
8. Slip the folded towel over the mask and tuck its base well
round the chin and face. Do this only after the first two
minutes have elapsed.
9. As soon as the neck muscles are relaxed, turn the patient’s
head over to one side, and let the hands assume the position
described in Chapter iii. and illustrated in Fig. 28C.
10. The student is warned to discourage the too early attentions
of the nurse or house-surgeon. These officials are naturally
anxious to “get the patient ready for the Chief” and are
apt to start “cleaning up” before the patient has lost all
consciousness. A man who is doing his level best to go to sleep,
derives neither pleasure nor profit from a wholly unexpected dab
of ice-cold methylated spirit upon his umbilicus.
By the use of the method here advocated, induction is singularly easy
and successful in good subjects. The struggling stage is either not
represented at all, or appears only in the form of the lifting of
a limb and a slight occasional pause or catch in respiration. Full
anæsthesia is often announced audibly, by the commencement of a gentle
“blowing.” Once it is heard, the anæsthetist may rest assured that a
workable level of anæsthesia is either present or not far off.
Amounts of Ether required.
If the above instructions are followed, the amount of ether required
is not excessive. Anæsthesia is attained after the use of about 1½ to
2 ounces of ether and one or two drams of mixture. The next forty to
fifty minutes demand about another four or five ounces of ether; no
mixture at all. Some practice, is required before these small figures
are attained. The more practice, the less ether is required.
III.--VAPOUR ANÆSTHESIA.
In a sense, all forms of ether anæsthesia are vapour methods, but
in all the forms so far described, the patient has to vapourise the
drug for himself: in a true vapour anæsthesia this is done for him,
and the mixture of air and ether vapour propelled towards him. One
of the keenest advocates of this method is Dr Gwathmey, of New York.
He lays great stress also upon the necessity of warming the vapour,
claiming that this measure will prevent the loss of heat to the patient
incidental to the warming up in the air passages of the cold vapour
usually supplied by other methods; but the results of the laboratory
experiments upon which Gwathmey founded his case are inapplicable to
the human subject, in that they were performed upon dogs and cats,
which lose heat largely from the mouth and air stream. Man is not a
hairy animal, and transacts most of his thermolysis through the medium
of his skin. None the less, warming the vapour of ether has value since
the process removes some of the irritant effects so marked in the case
of cold ether vapour.
Apparatus for the Vapour Method.
In 1913, Karl Connell described such an apparatus, which was then in
use at the Roosevelt Hospital, New York. The ether was vapourised by
dropping it into a warm chamber. Air was pumped into the chamber, and
carried the ether vapour in known percentage, and at known pressure as
shown by gauges. Such mechanism is ideal, but would certainly be rather
costly. Its great value was that it informed us with certainty what
proportions of ether in the atmosphere were necessary to induce and
maintain anæsthesia (_see_ Appendix II.).
A simple mechanism was brought out shortly afterwards by Dr Shipway, of
Guy’s, and is known as Shipway’s warmed Ether.
It consists essentially of the following parts (_see_ Fig. 29):--
(1) A small hand bellows (B).
(2) An ether bottle, with tube for delivery of air stream
dipping deeply into the fluid: the exit tube of course does not
dip in. The bottle stands in a metal pan in which water at about
75° Fahr. is to be placed (E).
(3) A thermos flask (W) in which is a metal tube (U). The
etherised air passes along this tube, and picks up heat from its
walls. The thermos is filled with water at about 180° Fahr.
[Illustration: FIG. 29.--Shipway’s warmed ether vapour
apparatus.]
(4) A mask upon which a towel or gauze is to be stretched: the
rubber tube bringing the air and ether is brought through the
covering material and delivers the anæsthetic vapour in the
region of the mouth.
(5) Additional to the above, there may be added a small
chloroform bottle (C). In specimens of the instrument containing
this convenience, there has, of course, to be a regulating tap
(T) at the head of the ether bottle, which will divert more or
less of the air stream towards the chloroform.
This little machine, somewhat resembling a cruet stand in its
appearance was widely used in France. Owing to the kindness of
the Edinburgh Red Cross Committee, one was provided for the Base
Hospital with which the author proceeded to Salonika, where he used
it extensively. The impression of it formed by himself and others
was that it was peculiarly easy to maintain with it a steady level
of anæsthesia. It had, however, no claim to banish post-anæsthetic
bronchitis and pneumonia, of which in spite of much anxious care and
thought, a fair number of cases were seen during the winter time
(_see_ page 151).
In using the machine, it is necessary to remember that from the
physical point of view, one is providing from the machine a small part
only of the total volume of air required by the patient.
The bellows are quite small: one squeeze of the hand will not supply
more than about the equivalent in volume of one or two fluid ounces.
The larger part of the volume required by the patient has to be
obtained from the general atmosphere, so that the percentage of ether
which may be as high as 25 in the exit tube, will be greatly lowered by
the time it reaches the patient’s respiratory tract.
* * * * *
The actual strength of ether breathed by the patient will depend upon:--
1. The force and frequency with which the pump is compressed.
(_N.B._ It is of course useless to pump during expiration).
2. The depth of ether in the bottle.
3. The temperature of the water bath in which the ether bottle
stands. The warm water should only be put in at the last moment
before starting, otherwise very strong ether vapour will collect
on the surface of the ether, and the first puff of the bulb will
expel a highly irritant vapour towards the patient.
With specimens of this machine which have the addition of the
chloroform bottle, it is perfectly possible to conduct even the
induction stage of anæsthesia; a mere trace of chloroform vapour will
be sufficient. It is unnecessary to give detailed instructions for the
use of the machine. A preliminary consideration of the above physical
facts, together with a little cautious practice, will enable the
student rapidly to acquire facility with the method.
IV.--RECTAL ETHERISATION.
For such operations as the removal of jaw or tongue there are obvious
advantages in being able to introduce ether vapour to the blood per
rectum, since the mouth and air passages are thereby left free for the
attention of the surgeon.
Many years ago this was attempted by vapourising ether and propelling
the vapour through a tube high up into the rectum. This method was
abandoned, as it led to a good deal of inflammatory trouble afterwards.
Recently, Dr Gwathmey suggested a new method of utilising the rectal
route which has largely overcome this objection.
Gwathmey’s Oil Ether Method.
This consists in passing into the rectum a mixture of olive oil and
ether. The bowel is first carefully washed out, and an hour before
operation, the patient receives a hypodermic of morphia, gr. ⅙;
atropine, gr. ¹⁄₁₂₀. A suppository of chloretone gr. v is also passed
into the rectum to act as a local sedative. Half-an-hour later, the
patient is put into the left lateral position, a soft catheter
attached to a funnel is passed some six inches up the rectum, and the
mixture of oil and ether poured into the funnel. It is wise to take at
least five minutes to introduce the whole dose.
The following table shows the dosage required:--
+------------------+-------------+------------------------------------+
| | Strength of | |
| Age of Patient. | Ether in | Quantity of Mixture required. |
| | Mixture. | |
+------------------+-------------+------------------------------------+
| Under 6 years | 50% | One ounce to each 20 pounds body |
| | | weight (no preliminary morphia) |
| | | |
| 6 to 12 years | 55% to 65% | Do. do. |
| | | |
| 12 to 15 years | Do. | One ounce to each 20 pounds body |
| | | weight (but use ¹⁄₁₂ gr. morphia) |
| | | |
| 16 years and | 75% | One ounce to each 20 pounds body |
| upwards | | weight with ⅙ gr. morphia as a |
| | | preliminary |
+------------------+-------------+------------------------------------+
In practice then, for the ordinary adult, one uses eight ounces of the
mixture, six ounces of which are pure ether. The oil and ether require
to be shaken together, but remain blended long enough for introduction.
In five or ten minutes, the patient begins to feel a rather pleasing
numbness and tingling in the lower, and later the upper extremities,
and drops quietly to sleep in about twenty minutes. In a large
proportion of cases, it is necessary to deepen the anæsthesia by the
use of the open mask for a few minutes, but once a deep anæsthesia has
been thus obtained, the absorption from the rectum will balance the
loss in expiration and maintain a good anæsthesia for three quarters of
an hour at least.
On return to bed of the patient, the nurse passes two tubes placed side
by side, as high into the rectum as she can; the end of a Higginson
syringe is inserted into one of them, and a considerable quantity of
soap and water is pumped gently into the bowel, escaping down the
second tube. The washing must be continued until all smell of ether
is removed. Finally the soapy water itself is washed away by a little
saline.
Unless there be some pre-existing local inflammatory disease of the
rectum (in which case the method should not be used), there are no
unpleasant sequelæ after oil ether. The chief objection to the method
is the amount of labour thrown on the nursing staff, which is so
considerable as to bar it from adoption as a routine. This should not,
however, be allowed to prevent its use in the limited number of cases
in which it is strongly indicated. These are:--
(1) Panic-struck cases who cannot face the ordeal of ordinary
methods.
(2) Nose, throat, and tongue operations where intratracheal
ether is not available.
CHAPTER X
INTRATRACHEAL INSUFFLATION OF ETHER
Intratracheal insufflation consists in driving a current of air under
pressure, through a tube introduced by way of the mouth and larynx,
deeply into the trachea. The current of air which is continuous,
returns between the tube and the wall of the trachea, and escapes
through the mouth and nose.
Certain Physical Considerations.
The work of Meltzer and Auer has demonstrated that this insufflation of
air into the trachea under adequate pressure ventilates the pulmonary
alveoli, and enables the normal diffusion of gases to be carried out
for many hours, independently of all respiratory movements. If the
air in its passage under pressure is made to pass through a chamber
containing ether, we are enabled to introduce into the pulmonary
alveoli, ether vapour of varying strength, and, by this means, to
maintain surgical anæsthesia.
* * * * *
THE ACTUAL PROCESS OF EXTERNAL RESPIRATION consists in the absorption
of oxygen from the alveoli into the blood of the lung capillaries, and
the elimination of carbon dioxide from the lung capillaries into the
alveoli. The oxygen has to be brought from the outside to the alveoli,
and the carbon dioxide has to be conducted from the alveoli to the
outside. Between the outside and the alveoli is the long airshaft,
consisting of mouth and nose, pharynx, larynx, trachea, bronchi and
bronchioles. In natural respiration the conduction of oxygen inwards,
and of carbon dioxide outwards, is carried through by a complicated
pumping mechanism. In ordinary inhalation anæsthesia, this mechanism is
entrusted with the task of introducing ether vapour into the alveoli.
In intratracheal insufflation the work of this natural pumping
apparatus is taken over by an artificial mechanism. In considering the
justification for this, the following points are to be noted:--
(1) The patient is unconscious--not naturally so as in
sleep--but unnaturally as the result of drugs; there is
therefore a probability that the elaborate natural mechanism
may not work smoothly--especially is there a danger that the
free airway may be interfered with. Intratracheal insufflation
obviates this danger.
(2) By means of the artificial mechanism, air is brought with
some force to the mouth of the bronchi, and thus a more rapid
and more powerful diffusion of gases takes place.
(3) The mechanism ensures the maintenance of a current of air
blowing forcefully from the trachea and larynx through the
pharynx, mouth and nose. This re-current continuous air-stream
effectively prevents the entrance of blood or any infectious
material into the bronchi and air cells, and thus the danger of
septic lung troubles is obviated.
(4) In certain intrathoracic operations the normal respiratory
mechanism is deliberately interfered with. Intratracheal
insufflation by the constant maintenance of sufficient positive
pressure, prevents or regulates the collapse of the lung
which occurs when the thorax is opened, and thus obviates the
necessity for the somewhat elaborate positive and negative
pressure cabinets and masks which had been devised for
intrathoracic operations.
(5) Incidentally it may be noted that intratracheal insufflation
of air provides us with an excellent means for performing
artificial respiration. Many instances have now been recorded
of its utility in this respect. Dr Elsberg records the case
of a patient who had taken morphia with suicidal intent, on
whom artificial respiration by this method was kept up for 12
hours, without any respiratory movements taking place, recovery
ultimately ensuing.
The Apparatus.
This consists of (_see_ Fig. 30):--
1. Instrument for producing air current (A).
2. Ether chamber and various regulating taps (B).
3. Device for warming vapour (C).
4. Safety valve (D).
5. Manometer (E).
6. Intratracheal catheter, with rubber tubing linking up the
various parts of the apparatus (H).
[Illustration: FIG. 30. Diagram of intratracheal apparatus.]
1. THE AIR CURRENT is obtained either by means of an ordinary
glass-blower’s foot bellows, or an electric motor may actuate a
rotatory blower which produces a current of air. The blower may be made
to rotate at a speed varying from 50 to 1000 revolutions per minute
(_see_ Fig. 31).
The foot bellows is simple and inexpensive, and there is no reason why
it should not be efficient. The electrically rotated blower is more
efficient, ensures a smoother air current, and saves much labour.
2. THE ETHER CHAMBER.--Ether vapour may be produced by either of two
methods. Fig. 32 shows Kelly’s instrument where air is blown over the
surface of a considerable quantity of liquid ether. Dr Meltzer[5]
maintains that the effectiveness of the etherization is proportional
to the diameter of the ether bottle. In this connection it may be well
to recall certain points pertinent to the subject of etherization. A
satisfactory etherization depends on the establishment in the blood
and tissues of an ether tension of definite strength. Boothby[6]
states that this tension should correspond to about 15 per cent. of
ether vapour in the alveolar cells. “If when this tension has been
established, less than 15 per cent. ether vapour is administered,
outward diffusion occurs from the tissues and blood to the air and the
anæsthesia becomes lighter.”
[Illustration: FIG. 31.--Electric blower to supply current of
air for intratracheal anæsthesia.]
[Illustration: FIG. 32. Kelly’s intratracheal apparatus.]
In an apparatus such as we are describing the strength of the ether
vapour depends on and is influenced by a variety of factors, among
which the following may be specially noted:--
(_a_) _The diameter of the ether chamber._--The larger the
diameter the stronger will be the ether vapour. The chamber is
generally kept two-thirds full: the less the empty space in the
chamber the stronger will be the vapour.
(_b_) _The rapidity of the air-current._--The larger the amount
of air passing over the ether the more rapid will be the
vapouration, with the result that the temperature of the liquid
ether will rapidly fall and the strength of the ether vapour in
the air will be correspondingly lowered.
(_c_) _The temperature of the liquid ether._--The higher the
temperature of the liquid ether the stronger will be the
percentage of ether vapour in the air. If the ether chamber is
placed in a bath of water which is maintained steadily at an
adequate temperature and if the rate of the air flow remains
constant, a constant strength of ether vapour will be given off.
It is well in this connection to remember that the boiling
point of ether is low and that a very high percentage of ether
vapour is readily obtained if the temperature in the water
bath is allowed to rise beyond 80°F. For further information
regarding ether percentages _see_ Appendix I and II.
Such an instrument as Kelly’s requires at its head a _regulating tap_,
movement of which is capable of diverting part of the air stream direct
to the patient without coming in contact with the surface of the ether.
In this way the maximum strength of vapour may be diluted as and when
required.
In Fig. 33 is shown Shipway’s instrument. Here the drug is dripped
into a chamber, the floor of which is kept warm. The ether volatilises
at once and the vapour is carried away by the air stream passing
through the chamber. The strength of ether vapour in this instrument is
regulated solely by the rate of drip which is in complete control of
the administrator.
Whichever method of making ether vapour is utilised the instrument
should be capable of producing a maximum at least of 15 per cent. to 18
per cent., and means must be provided to reduce this percentage at will.
3. DEVICE FOR WARMING VAPOUR.--It is doubtful if the warming of
inspired or insufflated vapour has any appreciable influence on
the body temperature, but there is a fairly general consensus of
opinion that if the ether vapour is warmed there is less likelihood
of irritation of the respiratory mucous membrane. It is to be noted,
moreover, that in intratracheal insufflation the natural apparatus for
warming the inspired air is put out of action. This warming can be
effected by the simple device of carrying the tube through a chamber of
hot water after it emerges from the ether chamber.
4. SAFETY VALVE.--Dr Meltzer insists very strongly on the necessity
of having a safety valve capable of controlling the maximum pressure
under which the air may enter into the intratracheal tube. By a
simple device, any excess of desired pressure will cause the air to
bubble through mercury and thus never reach the lungs. In this way any
possibility of accident from undue intrapulmonary pressure is obviated.
[Illustration: FIG. 33.--Shipway’s intratracheal
apparatus.]
5. MERCURY MANOMETER to indicate the pressure in the tube in m.m.
of mercury. It has been experimentally established[7] “that the
pressure in the trachea and in the bronchi is only a small fraction
of the pressure in the manometer outside of the body, and that the
intratracheal pressure grows considerably less with the decrease of
the diameter of the intratracheal tube.”
6. INTRATRACHEAL CATHETER.--It is essential to have an instrument of
adequate rigidity which can be satisfactorily sterilized. The ordinary
coudé catheters, or the silk web white enamelled cylindrical catheters,
are suitable. The size should be selected from a range of 18 to 25
French. It is preferable to err rather on the side of a small than a
large tube. An ordinary adult will require a tube of about size 22 to
24, a plethoric alcoholic, on the other hand, might need a 25.
A tube of too large a calibre interferes with the free return of air
and spontaneous respiration soon becomes too slow. Expiration is
prolonged, active, and laboured, and after a few minutes, respiratory
movements may cease entirely. The only way to meet such a situation is
to withdraw the tube and insert a smaller one.
TECHNIQUE OF ADMINISTRATION.--It is advisable in adults to administer
about three quarters of an hour before the operation, a hypodermic
injection of morphia (gr. ⅙) and atropine (gr. ¹⁄₁₀₀), or of
scopolamine (gr. ¹⁄₁₀₀) and morphia (gr. ⅙). The latter combination is
more efficacious in alcoholic subjects. In children, atropine alone
should be given.
It is to be remembered that intratracheal insufflation of ether is a
method of maintaining not of inducing anæsthesia. Induction is carried
out in the ordinary way. When this has been done, the catheter is
passed.
The introduction of the catheter does present some difficulty, but
this is largely overcome as skill and confidence are acquired with
practice. It may be carried out indirectly, or a view of the glottis
may be obtained by the aid of such an endoscope as Hill’s, and the
catheter inserted between the cords. The latter method is probably the
more satisfactory, but it is well to acquire the skill to pass the
catheter indirectly as in a certain small proportion of cases there are
obstacles to the use of the endoscope.
To facilitate catherization the pharynx and epiglottic region may
be cocainized with a 5 per cent. solution before induction. Hill’s
endoscope (Fig. 34) is distally illuminated by a small electric lamp,
which is connected with a small pocket battery. A useful modification
of this has been devised by Mr Dott. In it, the catheter is passed
along a separate compartment, so that the view of the glottis is
undisturbed. The point of the catheter comes into view at the distal
extremity of the endoscope and can be guided between the cords into the
trachea.
[Illustration: FIG. 34.--Hill’s Direct Laryngoscope.]
It is essential before attempting intubation, that there should be
thorough relaxation. The lower jaw should be so slack that a gag is not
required. The head is then placed in the occipito-shoulder position, or
is allowed to hang over the end of the table. The tongue is controlled
by forceps, and the endoscope passed slowly along its dorsum until the
epiglottis comes into view. The point of the endoscope is then passed
sufficiently far below the tip of the epiglottis to ensure that it will
not slip; too deep insertion must be avoided. The endoscope being held
in the left hand, the hyoid bone is lifted up by a tilting movement of
the hand. The glottis is thus brought into view. The catheter stiffened
by means of a probe is then passed through the glottis into the
trachea and the endoscope withdrawn. The bifurcation of the trachea in
the adult is at a distance of about 26 cm. from the incisor teeth. The
catheter should be marked accordingly, and inserted to a point just
short of this. The probe is then withdrawn, and connection made with
the air current.
It occasionally happens that unexpected difficulty is met with on
attempting to pass the catheter by direct vision. The larynx may be so
fixed that the glottis does not readily come into view; or in the case
of an intraoral neoplasm the view may be obstructed by the presence of
blood. In such cases the catheter can be introduced by the indirect
method. The middle finger of the left hand is passed along the dorsum
of the tongue until the epiglottis is felt. The index finger is then
used to guide the point of the catheter to the glottis through which
it is then passed. No undue force must be used. A stilette should be
inserted into the catheter which should be moulded almost to a right
angle at its terminal third. If the stilette is withdrawn when the
point of the catheter is over the mouth of the glottis, the instrument
will, as a rule, slip easily into the trachea.
Occasionally the tube passes into the œsophagus. With care and adequate
relaxation such a mistake should not occur, but the possibility of it
should be kept in mind. If the operator will abstain from attempting to
pass the catheter until such time as he has a satisfactory view of the
glottis, mistakes of this kind will seldom occur. The essentials are a
good illumination and an adequate relaxation.
Mild glottic spasm may supervene on the passage of the catheter but
this rapidly passes off. At first the degree of concentration of the
vapour should be low or irritation will result, evidenced by spasm and
coughing. The strength of the vapour is gradually increased until the
necessary concentration is attained. The pressure should vary according
to the requirements of the case and should range between 10 mm. to 25
mm. Hg. The safety valve must be set so as to make any pressure above
this impossible.
In the majority of cases the course of anæsthesia is smooth and
uneventful; the colour remains a rosy pink, the pulse is good, and the
respirations quiet and regular. It is undesirable that the respiratory
movements should be abolished altogether; their presence indicates that
neither the central nor the peripheral respiratory mechanism is being
overdosed with ether.
Theoretically, the constant plus-pressure in the lungs might be
thought to interfere with the circulation in the large veins, and
in the pulmonary vessels themselves. It is therefore well to reduce
the pressure in the catheter to zero every minute by opening the tap
provided for the purpose for a second or two.
At the conclusion of the operation, before withdrawing the catheter
it is well to flush out the lungs with air so as to remove any ether
vapour that is present. In a certain number of cases, notably in
big alcoholic subjects, difficulty may be experienced in securing
a sufficiently deep anæsthesia with good relaxation. It is seldom,
however, that patience and the careful introduction of a stronger
vapour will not suffice to overcome this. In alcoholic subjects, as
previously suggested, preliminary medication with scopolamine and
morphia will help. It really becomes a question, if one may put it
so, of coaxing the unconscious patient to tolerate an ether vapour of
adequate strength.
Advantages and Special Indications.
The general opinion of anæsthetists appears strongly to favour the view
that the absence of strain and the perfect æration in intratracheal
ether insufflation tend to lessen the shock of operation. The
post-operative history of patients also suggests that there is a
lessened liability to pulmonary complications as compared with cases
in which ether has been administered by other methods. Dr Elsberg[8]
of New York in this connection writes: “The absence of any pulmonary
complications has led us to use this method of anæsthesia in all
patients in whom pulmonary complications were to be feared after an
anæsthesia or operation. Thus on all asthmatics, in patients with
chronic bronchitis and emphysema, in patients who require gastric
resection and the like, we no longer, during two years, have seen the
much dreaded post-operative pneumonia wherever intratracheal anæsthesia
was used.”
In addition, there is ample evidence[9] that the introduction of a
catheter into the trachea and its presence therein does not tend,
as might have been expected, to set up any irritation at the time
or predispose to subsequent trouble. Apart from these general
considerations, which suggest the advantage of a somewhat extended use
of intratracheal ether insufflation, the method has obvious advantages
in all operations about the mouth, such as those for excision of the
upper jaw, those undertaken for the removal of nasopharyngeal growths
and various plastic operations involving the nasal and buccal cavities.
In such cases the danger of aspiration of blood, mucus, etc., is
obviated and the anæsthetist is well out of the surgeon’s way, while at
the same time an even interrupted delivery of ether vapour is effected.
In operations for removal of glands in the neck the surgeon has the
field to himself, and is not hampered nor is his asepsis endangered by
the proximity of the anæsthetist’s mask.
In such operations as laminectomy and nephrectomy the postural
difficulties with which the anæsthetist has to contend, and which also
tend to interfere with free respiration, are eliminated.
The great advantage of the method in intrathoracic operations has
already been referred to.
The introduction of intratracheal insufflation of ether was rendered
possible by the pioneer work of Drs Elsberg, Meltzer, and Auer. The
writer would like to acknowledge his indebtedness to their writings, of
which he has made free use.
CHAPTER XI.
CHLOROFORM.
Physical Characteristics.
Chloroform is chemically trichlor-methane, CHCL_{3}. It is a
colourless, transparent fluid, with a specific gravity of 1·491 at
17°C. Its vapour is even heavier than that of ether, approximately
four times heavier than air. It is not inflammable, but the action of
an open fire or naked flame tends to break it up into hydrochloric
acid and phosgene, both of which are highly irritant gases to all who
breathe them. The patient suffers, but since all the other occupants of
the theatre are also affected, warning is given before serious harm has
been inflicted.
Chemically pure chloroform is a somewhat unstable product, but the
addition invariably made to it by the producers, of a trace of
alcohol, prevents any serious risk of decomposition in bulk. It should
be neutral in reaction and have an agreeable non-irritating odour:
departure from the normal in either respect indicates the possibility
of the presence of acids or aldehydes, and the necessity for referring
a specimen to the laboratory.
Like ether, chloroform may be obtained from pure ethyl alcohol or from
methylated spirits, and the remarks made in the chapter upon ether
apply to the case of chloroform also. A third source of supply is
acetone, from which perfectly good chloroform can be produced.
Physiology.
Chloroform is an irritant to the skin and mucous membranes. A drop left
on the skin and covered over with impermeable material will produce a
deep and painful blister. A drop falling into the eye, if not instantly
washed away, produces a very powerful inflammatory reaction, and many
eyes have been totally lost from carelessness in this respect. Such
incidents are of course actionable, and heavy damages may be given.
[Illustration: FIG. 35.--Diagrammatic representation of
various blood pressure curves obtainable with chloroform.
Line ABA′ represents curve desired in normal chloroform
administration.
Line ABCB′ represents gradual overdosage.
Line ABCC′ represents recovery by inversion.
DD′ represents syncope from vagal inhibition: in its course,
one attempt of the heart to “escape” is shown.]
The special peculiarities of the action of chloroform upon the nervous
system have already been emphasised in the account given of the
physiology of ether (see page 75). Its action upon the _circulatory
and respiratory systems_ has been the subject of many researches,
and of much embittered controversy. The literature is therefore very
extensive, and the account of it must be severely condensed. The
following may be taken as a brief resumé of present day opinion (_see_
Fig. 35):--
(1) In every case of chloroform administration, there is a fall
of blood pressure.
(2) If the drug be presented in weak concentration (less than 2
per cent. vapour strength), the fall is gradual and even (line
AB).
(3) If the same strength (say 2 per cent.) of vapour as produced
the above effect be prolonged unduly, the respiration will cease
at a time when blood pressure is still well above zero (line
ABCB′).
(4) The fall of pressure is due to diminished force of cardiac
action, and at a later stage also to vaso-motor paresis.
(5) The cessation of respiration is due partly to fall of
blood pressure in the vessels supplying the medullary centre;
partly to gradual poisoning of the centre itself by the drug.
That the fall of B.P. in the cerebral vessels is in itself one
explanation of the cessation of respiration, was proved many
years ago by Leonard Hill in his inversion experiments. Just
at the stage when respiration had ceased, the anæsthetic was
withdrawn, and the animal inverted into the head-down position.
The B.P. in the carotid at once began to rise, and natural
respiration was resumed (line A′BCC′).
The above conclusions refer to chloroform given in moderate vapour
strength; other effects are produced if higher percentages are
administered:--
(6) With high concentration of chloroform vapour, the fall
of blood pressure is rapid, and is apt to become suddenly
precipitous (line DD′).
(7) The cause of these sudden falls is inhibition of the
heart by over-activity of the vagus: cutting the vagi always
terminates the effect unless delayed so long that the animal is
dead: in an animal fully under atropine, these vagal actions
cannot be produced.
(8) If the heart is inhibited by vagal action, the respiration
ceases at once, usually after one deep inspiratory sigh.
(9) An inhibited heart may “escape” from vagal action before the
animal is dead: frequently, however, the inhibition persists and
the animal dies.
(10) Struggling and breath-holding in the early stages of
induction cause sudden falls of blood pressure. Many observers
believe that these falls also are due to vagal activity, others
hotly deny this. All are united in believing that to _press_
chloroform upon a patient who is struggling and holding the
breath, is fraught with grave risk of causing sudden syncope.
(11) The abnormal irritability of the vagus above referred to is
a feature mainly of the induction stage, disappearing once full
anæsthesia is developed.
(12) It is an undoubted clinical fact that there is a risk
of sudden arrest of heart’s action if the operation is begun
before the stage of full anæsthesia is reached. A reasonable
explanation of such accidents is furnished by supposing a reflex
inhibition acting through the vagal centre already rendered
hyper-sensitive by partial chloroformisation.
Views of Goodman Levy.
This worker has demonstrated in animals that the heart is sometimes
thrown by chloroform into the condition of fibrillation--a delirium
of the cardiac muscle, from which recovery is rare. It occurs in
the early stage, before full anæsthesia has been reached, and is
predisposed to by the infliction of trauma. The practical outcome of
this is that the induction stage of chloroform should not be unduly
prolonged, and that the operation should not be begun until the third
stage is fully developed.
So far as the author understands the views of Dr Levy, his explanation
of chloroform syncope need not be taken as introducing any new
principle into the administration of the drug. Even those who lay most
emphasis upon the danger of using vapours of too high a percentage
strength would admit the force of Levy’s contentions. As usual, safety
lies in steering between two extremes.
During his work on this subject, Levy further demonstrated that
the introduction into the circulation of _adrenalin_ during
incomplete chloroform anæsthesia was very liable to induce fatal
cardiac fibrillation. He thus furnished the explanation of a number
of deaths which had occurred in the practice of nose and throat
specialists. Since the publication of Levy’s work, the rule has been
absolute that if _adrenalin_ is to be used in a case requiring
chloroform anæsthesia, the adrenalin must _precede, not follow_
the anæsthetic.
Administration.
Basing upon these views as to the action of chloroform, and upon the
lessons of practical experience, we may formulate definite rules for
giving the drug.
General Principles for giving Chloroform.
(1) Give chloroform evenly, not spasmodically.
(2) Increase the vapour strength of chloroform gradually from
zero until 2 per cent. or at most 2½ per cent. is reached at the
end of two or three minutes; maintain that strength until full
anæsthesia is obtained; thereafter, drop down to 1–1·5 per cent.
This will result in a B.P. curve corresponding to the line ABA′
in the diagram (Fig. 35).
(3) Be guided chiefly by the patient’s respiration. Chloroform
kills by stopping the heart, but in the immense preponderance
of cases, evidence of failure of respiration appears in ample
time to give warning of approaching circulatory failure. The eye
reflexes give confirmatory evidence of the depth of anæsthesia,
but the superlatively important thing is to _maintain a free
airway, and be sure the patient is using it_.
(4) If serious struggling and breath-holding occur, withdraw the
anæsthetic until the patient “resumes normal.”
Methods of Administration.
The logical application of such general principles would be to use an
instrument which gives a definite and known percentage of chloroform,
variable at the wish of the administrator. Many such machines have
been brought forward, and while none of them have obtained general
acceptance, a description of the best known instrument will be given,
as the reader may as a house-surgeon meet with it, and with a surgeon
who wishes it to be used.
Vernon Harcourt’s Inhaler.
In principle, this is a “draw-over” instrument; the patient’s own
inspirations are the motive power. Passing over the surface of the
fluid drug, the inspired air picks up from it a known percentage of
vapour. The other system available for the construction of percentage
chloroform instruments is the “plenum”; in this the vapour is propelled
to the patient by a pump.
[Illustration: FIG. 36.--Vernon Harcourt’s Percentage
Chloroform Inhaler.]
In appearance, the inhaler resembles the letter T, with a rubber
face-piece attached to the lower end of the vertical limb (_see_ Fig.
36). The T portion itself is made of metal tubing of a definite size
in cross section. One end of the horizontal limb admits pure air, the
other, air which has passed over chloroform and picked up from it a
certain proportion of vapour. The proportion of the total inspired
volume of air which passes through each of the ends is regulated by
a lever seen at the junction of horizontal and vertical limbs, and
the exact percentage of chloroform being inhaled is indicated by a
series of numerals marked on the dial over which the lever moves. These
figures are correct provided:--
(1) The chloroform receptacle is not shaken (this would greatly
increase the percentage).
(2) The temperature of the chloroform is not allowed to fall
below 13° centigrade. To ensure that this cannot take place
without the knowledge of the administrator, two coloured beads
are thrown into the chloroform. At the desired temperature of
the chloroform (13°–15°C) the blue bead sinks to the bottom,
the red one nearly to the bottom. Below 13°C, the red bead also
touches bottom, and when this is observed, the chloroform vial
is warmed up in the palm of the hand. At the point 15°C, both
beads float, and the warming must then stop, or an undesirable
addition to the vapour strength yielded will occur.
The face-piece is made of rubber, and must be closely adapted to the
face; in its side is seen the expiratory valve. Inspiratory valves are
present at each end of the horizontal limb.
The great advantage of this instrument, to the author’s mind, is for
teaching or demonstration purposes. If the student _sees_ the lever
gradually being moved over from ·2 to 2 per cent., then slipped back to
about 1·5 per cent. after full anæsthesia has been obtained, he begins
to appreciate what it is he is aiming at when giving chloroform by the
ordinary open method.
[Illustration: FIG. 37.--Schimmelbushch’s mask.]
Open Method.
The appliances requisite are:--
(1) A mask. Schimmelbushch’s is the best known (Fig. 37): as
elsewhere explained, it does not accurately fit the face.
(2) Material to stretch on the mask. The best is two layers of
domette or one of flannelette: surgical gauze is so light that
heavy drops of chloroform are apt to “spark” through it and burn
the skin of the face: lint rapidly becomes sodden; the drug
drips away from its edge instead of vapourising properly.
(3) A good drop bottle, of which many varieties are marketted
(Fig. 38): it is essential that it should be capable of
producing definite _drops_: the old method of intermittent
“douching” of chloroform is to be condemned as violating the
first general principle for giving the drug.
[Illustration: FIG. 38.--Chloroform drop bottles.]
It is not possible by the open method to be mathematically accurate
with percentages, but the necessary appliances are simple, easily
transported, and practically always at hand. If the student learns to
use it, and while doing so _to think in percentages_, he will
achieve as good results as or better than he will with percentage
instruments. While he may not have in front of his eyes a dial which
shows the percentage graphically, observation of the patient will
inform him whether the percentage being given should be maintained,
raised, or lowered. The only remaining point for him to realise, then,
is how in practice such regulations of percentage strength can be
achieved by the open method. The strength of the vapour will depend
upon three factors:--
(1) Nature of the material used on the mask.
(2) Closeness with which the mask is adapted to the face.
(3) Amount of chloroform exhibited on the mask.
To ensure uniformity of result, two of these factors should be kept
constant, and the necessary increase or decrease of vapour strength
achieved by varying the third. Always use the same type and thickness
of material on the mask, and allow the mask to lie lightly on the face.
If the amount of chloroform is then regulated by a strictly “drop”
method, results of great uniformity may be obtained by the open method.
The Junker Inhaler.
This instrument was originally introduced as an attempt to achieve a
percentage method. Air is pumped through a certain depth of chloroform
contained in a bottle, and the vapour brought to the patient in the
face-piece shown in Fig. 39. The calculations by which it was sought
to establish this as a reliable dosimetric or percentage method are of
no great value. From that standpoint the instrument has not achieved
success. It delivers to the patient a _small quantity of high
percentage vapour_ which is diluted by a much larger quantity of
air inspired by the patient from the general atmosphere, and the final
percentage inhaled by the patient is therefore no more accurately known
to the administrator than in the open method.
The instrument is, however, of considerable value for tongue and jaw
cases, where anæsthesia has to be maintained for some considerable
time after the mask with which anæsthesia has been induced has had to
be removed, to give access to the surgeon.
[Illustration:
FIG. 39.--Junker’s Chloroform Inhaler showing hand
bellows, bottle and mask. Alternatively to the latter, the
nasal tube shown above, may be used.]
The Figure 39 shows the instrument as usually marketed. It consists
of:--
(1) A hand-bellows.
(2) Chloroform bottle. A mark cut on this shows the level to
which it is to be filled: if more than the proper quantity be
poured in, droplets of fluid chloroform are apt to be blown
along the exit tube, with dangerous results.
For convenience and neatness, it is usual to make the exit surround
the inlet tube. The entering air bubbles through the chloroform,
and a stream of air and chloroform vapour passes out from the exit
tube.[10] It is unnecessary to give a detailed account of the use of
the instrument, but the student must remember the following points:--
(1) The amount of chloroform vapourised will depend on the
vigour of the pumping, the depth of fluid, and the temperature
of the chloroform. In order to achieve uniform results, it
is therefore necessary to keep up a steady but not excessive
pumping, to warm up the bottle occasionally by holding it in the
palm of a disengaged hand, and to watch that the level of the
chloroform does not fall too low.
(2) The pumping should be timed to synchronise with inspiration:
a puff of vapour delivered during an expiration will be wasted.
Advantages and Disadvantages of Chloroform.
The light portable appliances which are alone necessary for chloroform
anæsthesia, the comparative cheapness of the method, and the _apparent_
ease with which its administration may be conducted, are all great
temptations to its use. Those who feel the temptation strong upon them
are advised to remember the following quotation from the writings of
Professor Leonard Hill:--
“Chloroform is a drug used by the young anæsthetist with the utmost
hardihood, and until he has had the misfortune in his practice to meet
with a death caused by it, he derides the danger of the drug, and
asserts that its safety merely depends on the care and skill of the
administrator. After losing his patient, he falls to descanting on the
unavoidable dangers of the drug, dangers which he is now the first to
maintain cannot be met by any degree of skill in administration.”
The most distressing and probably the most common chloroform fatalities
are exemplified in administration given for the most trifling
conditions, such as opening abscesses or extracting teeth.
In general, we use chloroform if for any reason ether is not
applicable. For examples of cases of this description, the reader is
referred to the chapter upon the choice of anæsthetics.
CHAPTER XII.
ETHYL CHLORIDE.
Chemically this drug has the formula C_{2}H_{5}Cl. It is a colourless
fluid so volatile that it boils at ordinary room temperature. Its
vapour is highly explosive, and the fluid itself very inflammable. The
drug is supplied by the makers in small tubes with a metal end which
can be opened by pressing a little lever (_see_ Fig. 40), varying
in type with the brands made by various makers. Two brands are sold
by each firm; one is chemically pure, intended for use as a general
anæsthetic; the other is not so pure, and is only sold for local
anæsthesia. Such a product is not suitable for inhalation.
[Illustration: FIG. 40.--Tube of Ethyl Chloride.]
Physiology.
The special points in the physiology of ethyl chloride may be briefly
summarised as follows:--
1. After a trifling preliminary rise, the effect of the drug
is to lower the blood pressure appreciably. In the human adult
subject, this fall becomes appreciable when more than 3 c.c.
have been given; if the dose exceed 5 c.c. a fall of 30 to 40
mm. of Hg. is probable,--occurring as it does within a period of
perhaps twenty or thirty seconds, such a fall cannot be regarded
as safe.
2. The cause of this fall is diminished cardiac output from
weakening of heart muscle. The vagus though not paralysed, does
not appear to be unduly irritable, as it does with chloroform.
3. The respiratory centre is at first perceptibly stimulated,
and respiration is therefore deeper and quicker than normal. The
stimulant effect rapidly passes away and gives place to a stage
of depression.
In the majority of cases, death appears to take place from paralysis
of the respiratory centre, the heart still showing a little power of
contraction after respiration has ceased. There is therefore a fair
prospect of recovery if artificial respiration be resorted to promptly.
Methods of Administration.
OPEN METHOD.
The extreme volatility of the drug has discouraged most anæsthetists
from giving it upon an open mask. Hornabrook, of Melbourne, advocates
this system, however. His mask fits the face accurately, and his whole
method is strictly perhalational. He uses some 4–6 c.c. of the drug
for a child, 6–8 c.c. for an adult, and achieves his anæsthesia in a
minute to a minute and a half. He also advocates open ethyl chloride
as a preliminary to open ether. For some twelve months, the author
adopted the method. At the end of that time he came to the conclusion
that while it greatly facilitated the induction stage of open ether,
it appeared to increase the after sickness. He therefore abandoned it,
though rather reluctantly.
CLOSED METHOD.
This is the usual means employed. A variety of inhalers have been
produced on the market, one of which is shown in Fig. 41. Essentially
all consist of:--
(_a_) A face-piece which must fit the face with reasonable
accuracy.
(_b_) A one-gallon rubber bag attached to the mask by a
T-piece.
(_c_) A glass vial, with numerals from 1 to 5 marked on the
outside to facilitate the measurement of the drug in c.c. Into
this the drug is squirted from the makers’ tube. The vial is
attached to the T-piece (or alternatively the bottom of the bag)
by a rubber tube.
[Illustration: FIG. 41.--Ethyl Chloride Inhaler.]
Administration.
To use such an inhaler, the glass vial is first detached from the
rubber tube, and the chosen dose of drug squirted into it. A child
of five or six will require 3 c.c., an adult up to 5 c.c.; this dose
should never be exceeded. The vial is then rapidly reconnected with
the inhaler. The face-piece is adapted to the face, care being first
taken to place between the teeth a mouth prop or a gag. This enables
one to get immediate access to the mouth when the inhaler is removed.
The patient is then told to breathe deeply once or twice. During the
inspiration the mask is lifted slightly, and the ensuing expiration is
then caught in the bag by pressing down the mask on to the face. To
volatilise the drug there are two alternative methods. In the one, part
or the whole of the dose is tipped into the rubber bag by elevating the
vial. A far better is the “Vapour” method, almost universally used in
Edinburgh owing to the advocacy of Dr Logan Turner. A tumbler is filled
with hot water, and the bottom of the glass vial is allowed first to
touch, and after a few seconds to be immersed in it. Some thirty to
forty seconds suffice to vapourise the whole of the dose.
Ethyl chloride given by itself should always be administered to a
patient in the recumbent position. A dose sufficient to produce
anæsthesia without the aid of nitrous oxide or ether will not be safe
in the erect posture. The case is quite different where a small dose
only is given, to assist the action of nitrous oxide, or facilitate the
induction stage of ether.
Signs of Anæsthesia.
Ethyl chloride is very rapid in its action, some sixty seconds
availing to produce quite a deep anæsthesia. _Respiration_ is
at first deepened and quickened: as full anæsthesia is attained it
remains rather deeper than normal, and is accompanied usually by light
snoring. The colour should remain perfectly good: the pupils show
marked dilatation, the corneal reflex is abolished, and good muscular
relaxation is attained.
With no anæsthetic is it so essential as with this, to become
acquainted with the type of respiration normally to be expected, and to
watch for any departure therefrom with cat-like vigilance. The other
danger signal is the pupil. It should be dilated, but a rim of iris
should still be perceptible.
Once anæsthesia is established, the inhaler should be removed, and the
surgeon may begin his work. He will have for its completion some 80–90
seconds against the 40–50 available after nitrous oxide. With ethyl
chloride there is a somewhat prolonged “analgesic” stage. The patient
is partly conscious and may even be phonating, but seems unconscious of
the infliction of pain unless very severe measures are being used.
The Scope of Ethyl Chloride.
When first introduced, it was expected by enthusiasts that the
lightness and portability of the drug itself and of the necessary
inhaler, would enable ethyl chloride to oust nitrous oxide from its
recognised place in surgery and dentistry. These high expectations
have for several reasons not been fulfilled. In the first place, this
drug is essentially a “single dose” anæsthetic. Most authorities view
coldly all attempts to prolong anæsthesia by repeated or continued
administration. Secondly, ethyl chloride has a mortality rate very
much greater than nitrous oxide if doses sufficient in themselves to
produce anæsthesia are habitually used (_vide supra_). The introduction
of the “vapour” method has done much to mitigate the risks, but even
then, this anæsthetic cannot approach the high level of safety rightly
credited to N_{2}O. Moreover, it leads to after vomiting much more
commonly than its rival.
In many schools these considerations have been held so powerful that
ethyl chloride has been entirely abandoned. It is, however, a very
valuable drug for the following purposes:--
(1) The removal of tonsils and adenoids. For this operation,
the speed with which the patient (usually a child) loses
consciousness, the pleasant type of anæsthesia and absence of
all serious asphyxial phenomena, and the rapid re-appearance
of the cough reflex when once the inhaler is removed, are all
strong recommendations.
(2) As an adjuvant to gas, or gas oxygen (_see_ Chapter
XIII.).
(3) As a help to the speedy and comfortable induction of “closed
ether” (_see_ Chapter XV.).
CHAPTER XIII.
MIXTURES OF NITROUS OXIDE AND ETHYL CHLORIDE.
Dr Guy, Dean of the Edinburgh Dental School, introduced some years
ago a method of giving ethyl chloride in mixture with nitrous oxide.
Guy’s objective was to utilise the many excellent features of the drug
without incurring the risks which are apparently inherent in it when
a dose sufficient in itself to induce full narcosis is used. Given in
mixture with gas, a much smaller dose suffices.
[Illustration: FIG. 42.--Guy’s inhaler for N_{2}O and Ethyl
Chloride.]
His original apparatus is shown in Fig. 42, the details are shown in
Fig. 43. The horizontal limb of a 3-way gas tap is prolonged half an
inch. In each side of the prolongation is a hole. The bag mount has
in its side also one hole, which is connected by a universal ball and
socket joint, with the rubber tube to which the ethyl chloride vial is
attached. An indicator on the outside of the bag mount and a mark upon
the outside of the horizontal limb of the 3-way tap, serve by their
apposition or the reverse to show whether the ethyl chloride vial is in
direct continuity with the interior of the inhaler. For purposes of
description, Dr Guy calls these two positions, “in register” and “out
of register.”
To use the instrument, the ethyl chloride vial is removed, and the side
pipe attached to a cylinder of nitrous oxide. The indicator of the
3-way tap is put at “air” and the bag mount “in register.” The bag is
then filled with gas by opening the head of the cylinder. The bag mount
is now put “out of register,” and the side tube disconnected with the
cylinder. The bag, being closed, remains full of gas.
[Illustration: FIG. 43.--Guy’s Instrument for Gas and Ethyl
Chloride. Details of valve piece and bag mount, showing side
tube for attachment of Ethyl Chloride vial.]
A suitable dose of ethyl chloride is now squirted into the vial. To
an adult, Dr Guy gives 3 c.c.: on no account is this dose exceeded:
children take 1½–2 c.c.--even adults often get less than 3 c.c. The
vial is now attached to the side tube again, and the inhaler is ready
for use.
After application of the mask to the face, the 3-way tap is at once
pushed over to “no valve” and the patient rebreathes the gas in and out
of the bag for some six or eight respirations. The bag mount is now
turned round “into register,” and the ethyl chloride tipped into the
bag. In a further twenty-five seconds the mask may be removed and the
operation begun.
The available period of anæsthesia is eighty to ninety seconds,
counting from the instant of the removal of the inhaler.
This method was in use for some years at the Dental Hospital of
Edinburgh; no instance of danger to life was ever seen. With so small a
dose of ethyl chloride, the erect position necessary for the purposes
of dentistry is perfectly safe.
[Illustration: FIG. 44.--Diagram of the method
introduced by Dr Guy and the author for giving Nitrous Oxide
and Oxygen, with or without Ethyl Chloride.]
This inhaler, of course, will serve admirably for giving ethyl chloride
without gas, and the author habitually uses it for giving the drug by
the “vapour” method.
In 1911, Dr Guy and the present author modified the method so as to
permit the use of oxygen with the nitrous oxide. The inhaler which
they then introduced serves also for nitrous oxide and oxygen, unaided
by ethyl chloride, and the author has by its means given gas-oxygen
to a considerable number of major surgical cases. He now, however,
limits its use to short anæsthesias, and uses a sight-feed or a Clarke
apparatus for long cases.
[Illustration: FIG. 45.--The Guy-Ross Inhaler for
Nitrous Oxide and Oxygen, with or without Ethyl Chloride.]
In Fig. 44 will be found a diagram showing the method by which the
oxygen is introduced. The 1-gallon oxygen bag is either attached
directly to a cylinder, or suspended on an upright as shown in Fig.
45. In either case, the bag is, before the administration, moderately
filled with oxygen: one bagful will suffice for a short anæsthesia, and
the supply of the oxygen from the cylinder is therefore turned off at
once. For long cases, of course, a small trickle of oxygen into the bag
is required to replace the gas used.
In the outlet pipe from the oxygen bag is placed a ball syringe of 2
ounces capacity. A valve in the pipe obliges the flow of oxygen to take
place in one direction only when the bulb is squeezed, viz. from oxygen
bag to inhaler.
The remainder of the apparatus is identical with Guy’s original
inhaler, except that the bag is of 2-gallon capacity, and is perforated
at its base by a =Y=-tube, one limb of the fork bringing in the
nitrous oxide, the other the oxygen.
Method of Use.
A few breaths of pure nitrous oxide gas are usually allowed “on the
valve.” Rebreathing is then instituted, and the addition of oxygen
begun. The amount required to each type of patient can only be learnt
with experience, but the average is one full compression of the bulb
every ten seconds. If anæsthesia is not complete at the end of one
minute, put the indicator to “valves” again, and allow the patient
nearly to empty the bag. Then push back the indicator to “no valves,”
and refill the bag with nitrous oxide by opening the cylinder with the
foot key. Some four to six compressions of the bulb are made while the
nitrous oxide is running in. The time will now have come to add the
dose of ethyl chloride if it be judged necessary at all. This will have
been placed in the vial before the administration is begun. After
emptying the ethyl chloride into the bag of the inhaler, anæsthesia
should be complete in twenty-five seconds.
The same small doses of ethyl chloride are used as is the case with
Guy’s original method.
After a little practice under supervision, students at the Dental
Hospital learn to use this method safely and well. No example of risk
to life has arisen after eight years’ daily experience.[11]
CHAPTER XIV.
MIXTURE OF CHLOROFORM AND ETHER.
The mere addition of ether does not remove all the undesirable features
of chloroform anæsthesia. A heart poisoned by excess of CHCl_{3} does
not respond to ether stimulation. Nevertheless, CE mixtures of varying
proportions have great value. The less lethal drug takes on part of the
work of the more dangerous one; it also keeps the respiratory centre
active. Viewing mixtures as dilute chloroform, it is also obvious that
there will be with them a greater margin of error in dosage, than with
the pure drug.
Some chemical change takes place when the two drugs are mixed, for heat
is evolved; of the nature of this change we are ignorant.
The first mixture introduced was known as ACE, and consisted of one
part absolute alcohol, two parts chloroform, and three parts ether.
Alcohol evaporates very slowly and if it be introduced at all it should
be in much smaller proportion. Schäfer’s mixture is one part alcohol to
nine parts chloroform. Neither of these mixtures is now much used. The
most useful combination is two parts chloroform and three parts ether,
and is known as C_{2}E_{3}. In special cases, one part of chloroform to
two parts ether may be better.
Methods.
_Cones_ of varying type were at first extensively used for
mixtures. The best known is Rendle’s (Fig. 46). It is made of
celluloid, and is perforated at the top by a series of small holes
through which the anæsthetic is introduced. A sponge is packed into
the upper part of the cone, and a flannelette cover completes the
appliance. The objection to the use of this and kindred cones is that
since chloroform evaporates more slowly than ether, the more dangerous
drug is apt to collect in the sponge, completely altering the strength
of the vapour after a time. This fault is remedied to a large extent by
the open drop method now used.
[Illustration: FIG. 46.--Rendle’s Cone.]
The Open (Drop) Method.
For this the mask and ether dropper of Bellamy Gardner are admirably
suited (Fig. 27). A material less close than the gauze advocated for
open-ether is required. One layer of flannelette does very well, or
the cheap cotton towels which used to be known in Edinburgh as “penny
towels” in the pre-war period. The mask should fit the face with
reasonable accuracy: there is no reason why a gauze ring should not be
used to ensure this if the administrator is careful to adhere strictly
to a “drop” method.
The bottle into which the dropper is inserted should be of different
_colour_ to those in which pure ether is habitually carried. This is a
greater safeguard against a dangerous forgetfulness than a mere label.
As already said, the anæsthetic must be given by a strict “drop”
method. “Douching” at frequent intervals gives results far inferior.
THE TYPE OF ANÆSTHESIA is a compromise between that of chloroform
and open-ether. Respirations and colour are better than with pure
chloroform, not so good as with open-ether. The size of the pupil is
also intermediate.
SCOPE.--As elsewhere explained there are many patients to whom
open-ether cannot well be given; the greatest number of these can take
a mixture perfectly and C.E. should certainly be chosen in preference
to pure chloroform when possible. For refractory cases, it serves
admirably as the inducing agent before the use of open-ether.
CHAPTER XV.
SEQUENCES.
By a sequence we mean a method in which anæsthesia is partially or
wholly induced by one anæsthetic or one method, and maintained by
another. The methods mentioned in Chapter XIII. as devised
by Dr Guy for dental purposes are examples which have already been
sufficiently described.
C.E. Mixture--Ether Sequence.
Of the method of inducing anæsthesia by _C.E._, and turning later to
_open-ether_, we have also already spoken. One thing remains to be
said in this connection. Learn to judge the appearance of the type of
patient who will require this alternative to open-ether induction, and
use the sequence to such patients from the beginning. Don’t start off
with open-ether, and find out in a few minutes that the patient is too
obstreperous. A change from mixture to ether is harmless, the reverse
process needs much care.
The sequence of _C.E. to closed ether_ was advocated by Hewitt as a
means of dealing with very alcoholic men, and for this purpose has
great merits. The mixture is given until the stage of struggling is
just about to commence, a point which experience enables one to fix
with considerable accuracy. The remainder of the induction is conducted
by a closed-ether inhaler, either the Hewitt wide-bore or preferably
the Ormsby. The ether indicator which stands at about one when the
inhaler is first applied, may be advanced very rapidly full ether
strength being attained within a minute or two. As soon as rebreathing
is begun with either of these instruments, it is very striking to watch
the rapid and apparently safe subsidence into anæsthesia of the most
troublesome patient. The struggling is cut short and greatly minimised
in violence, and a stage which under CHCl_{3} might have presented some
considerable risk of secondary syncope, is thus eliminated.
Nitrous Oxide and Ether Sequences.
This is a method greatly superior to the induction by closed-ether
described on p. 79. Instead of the 1-gallon bag of the Clover or Hewitt
instrument, the valve piece and 2-gallon bag of a gas apparatus are
attached to the head of the ether inhaler (Fig. 23, on page 77).
Once the gas bag is inflated from the cylinder, the supply of gas may
be cut off. A few breaths of gas “upon the valves” are given, until the
bag is half empty; the valve tap is then pushed over to “no valves” and
rebreathing begun. Ether may be turned on a few seconds later, and the
strength of the vapour may be increased more rapidly. Three-quarter
strength of ether may be attained as a rule in ninety seconds. There is
very little likelihood of struggling in this method.
Ethyl Chloride and Ether.
This is a valuable method for short operations, being easily portable,
speedy and safe in action, and fairly agreeable to the patient. Some
anæsthetists use this induction method as a prelude to open-ether.
The Clover (or Hewitt wide-bore) instrument is interposed between the
face-piece and the T. of the ethyl chloride inhaler, as shown in Fig.
47. A small dose of ethyl chloride only is requisite; for an adult, 3
c.c. is enough. This is vapourised over hot water in the usual way; a
very light anæsthesia is induced in some sixty seconds, and the ether
can then be turned on at a much quicker rate than if the induction be
conducted by that drug alone.
Scope.
The gas-ether and ethyl chloride-ether sequences are most useful
methods. They are quick, safe, and powerful.
[Illustration: FIG. 47.--Clover’s Inhaler adapted
for the Ethyl Chloride-Ether sequence.]
Either may be used as “single dose” anæsthetic, the ether being pushed
quickly up to “full” and the inhaler then withdrawn. If, however, no
access to the mouth is required by the surgeon, ether anæsthesia may,
by occasional breaths of fresh air be prolonged for as long as desired.
CHAPTER XVI.
THE ACCIDENTS OF ANÆSTHESIA.
The minor difficulties of anæsthesia have already been dealt with,
and if the instructions already given, particularly in Chapter
III., are faithfully carried out, incidents of real danger
will rarely occur. The soundest knowledge and the most conscientious
care will, however, never entirely rid anæsthesia of an element of
danger to life. The conditions now to be considered are:--
(_A_) Vomiting.
(_B_) Failure of respiration.
(_C_) Failure of circulation.
(A) Vomiting.
This always exposes an unconscious patient to the danger of inhaling
solid or fluid material into the larynx, with resulting asphyxia. If
the patient be tided through that immediate difficulty, he is liable to
develop an inhalational pneumonia subsequently.
A healthy patient properly prepared should not vomit during the
induction stage, nor during the progress of the operation. If he
does, it means that the induction has been too slow, or that the
administration has been intermittent, and the patient has been
permitted to come to too light a level of anæsthesia during the
operation.
During emergency operations where the patient’s stomach may be full of
food, the case is different. Such patients commonly vomit early in the
induction stage, and no skill can avert the incident.
A patient suffering from intestinal obstruction, or from generalised
peritonitis has his stomach and intestines full of highly infective
fluid. Reverse peristaltic may set in merely as the result of the
inhalation, or later from handling the contents of the abdomen, and
the feculent fluid gushes up the œsophagus with little or no warning.
Since vomiting in these cases may occur even in deep anæsthesia, when
the cough reflex which is the normal sentry to the entrance of the
larynx, is abolished, the dangers of insufflation are very real indeed.
Personally, the author prefers to wash out the stomach before beginning
to induce anæsthesia in these cases, but some surgeons believe that the
shock of this procedure outweighs the advantages.
SYMPTOMS AND TREATMENT OF VOMITING.
In ordinary cases, vomiting is usually heralded by a definite train of
symptoms. Respiration becomes shallow, the colour a little pale and the
pulse rather small. The pupil dilates, but remains active to light,
indicating that the alteration of respiration and circulation is not
due to overdose.
At the first appearance of such symptoms, a brisk rub of the lips and
thereafter an increase of the vapour strength of the anæsthetic will
often avert the impending vomiting by deepening the anæsthesia, but if
the possibility of this complication has occurred to the anæsthetist
too late for its prevention, the head must be turned well to one side,
and the other shoulder slightly elevated by a pillow, so that vomited
material will fall out of the mouth at once. When the actual act of
vomiting is over, no time must be lost in mopping out the mouth and
pressing on with the production of a deeper anæsthesia.
(B) Respiratory Dangers.
These divide themselves into two groups:--
(1) MECHANICAL.--The respiratory movements continue, but the
ingress and egress of air is blocked.
_The symptoms and preventative treatment_ have been referred to at some
length in Chapter III., and no further account of these is therefore
necessary. _The treatment of a complete blockage_ of the air passages
which resist the measure there described, alone remain to be mentioned.
Of these, the only two effective are _artificial respiration and
tracheotomy_ (or laryngotomy if preferred by the surgeon). Forcible
artificial respiration by the Sylvester method, with the mouth gagged
open and the tongue held forward by the tongue forceps, is frequently
successful in getting over even a complete block, but the last resort
of opening the air passage by the knife must not be delayed until too
late. In deciding such a point, considerable judgment is of course
called for.
(2) NON-MECHANICAL.--Respiratory arrest.
This is usually seen in conjunction with a serious failure of the
circulation caused by over-dosage. Exceptionally, some act of the
surgeon sets up a reflex inhibition of the respiratory centre; the
circulation is at the same time depressed, but to a varying degree.
The cardinal _symptom_ is arrest of all respiratory effort. The
_treatment_ is best dealt with under the heading of circulatory
failure.
(C) Circulatory Failure, or Syncope.
By the term syncope, we mean a more or less sudden failure of the
cardiac pump, as opposed to the form of circulatory failure seen in
surgical shock, where the condition is chiefly, though not wholly, one
of vaso-motor paralysis (_see_ Chapter II.).
Syncope occurs under varying conditions which may for descriptive
purposes be divided into four classes. It is not, however, always
possible to decide with certainty into which class an individual case
should be placed.
The _symptoms_ common to all classes of syncope are:--
(1) Pallor, and loss of all tone in the muscles, noticeably
those of expression. The pulse is weak or imperceptible.
(2) Cessation of respiration.
(3) Dilatation of the pupil, which ceases to react to light.
The four classes above mentioned are as follows:--
A. PRIMARY SYNCOPE.
This is peculiar to chloroform. With no other anæsthetic is it seen, at
any rate in the healthy subject. It arises during the induction period,
and is not necessarily preceded by any respiratory difficulty. There is
one big inspiratory gasp, sudden and extreme pallor, and the pupil goes
out to the rim in a few seconds. The only reasonable explanation of
such an incident is the occurrence of vagal inhibition (_see_ page
112). Its prevention therefore is a matter of the avoidance of a high
percentage of chloroform.
B. SECONDARY SYNCOPE.
This term is applied to a collapse arising as a secondary result of
embarrassed respiration. Though not peculiar to chloroform, it is
far more common with that drug than with any other (ethyl chloride
excepted). The most common time for the accident is towards the end
of the induction period. The patient has probably been struggling,
has clenched the jaws, and developed “mechanical” asphyxia. Violent
inspiratory efforts are still being made, and considerable cyanosis
develops. Either at the very moment when the respiratory difficulty
is overcome, or while it still persists, the colour suddenly alters
from blue to white, and the other symptoms of syncope rapidly appear.
The exact period required to transform a blue struggling patient with
heaving chest, into one with pallid face, and motionless chest and
limbs, varies greatly, for reasons furnished below.
The most reasonable explanation offered of such an accident is that
given by Leonard Hill. The attempts to inspire through an air way
mechanically blocked cause an immense strain upon the heart muscle. The
flow of blood in the lung capillary is hindered, and the right side of
the heart becomes over distended with blood. Its musculature is further
damaged by the fact that the blood in the coronary vessels is deficient
in oxygen, and that a considerable dose of anæsthetic has already been
absorbed. There is the further fact, not mentioned by Hill, that during
the whole period of asphyxia the peripheral resistance is rising from
vaso-constriction. Under circumstances such as these, it is obvious
that _any_ heart must ultimately succumb, _no matter what anæsthetic is
in use_. It is also obvious that with chloroform and ethyl chloride,
which are themselves heart poisons, secondary syncope will happen much
more readily than with ether or nitrous oxide, which are not; and that
a heart with diseased musculature will fail quicker than a healthy
organ.
Secondary syncope is almost certainly the commonest fatal accident of
anæsthesia. The reason why this fact is not more widely recognised
arises from the natural instinct of any one who has suffered the misery
and ignominy of causing a death under an anæsthetic, to attribute it
to some cause beyond human control. The _essential_ cause of secondary
syncope is failure to maintain a free air way, which cannot be styled
unavoidable. Two consolations may, however, honestly be offered to the
person who has acted as anæsthetist in a case of secondary syncope.
Firstly, it is, in certain types of cases, very difficult indeed to
maintain a free air way; and secondly, a heart with muscle degenerated
from fatty or other changes, may give out after very little respiratory
embarrassment.
SYNCOPE FROM OVERDOSE.
This is a more gradual affair than the two foregoing; and has been
sufficiently dealt with in the chapter devoted to the Stages of
Anæsthesia (see p. 36).
C. REFLEX SYNCOPE.
Exceptionally, a patient not overdosed with anæsthetic, and not
suffering from any mechanical obstruction to respiration, has a sudden
attack of syncope during the progress of the operation. We here exclude
patients who are suffering from surgical shock; the condition arises
too rapidly for such an explanation to be accepted. Much speculation
has been expended upon these cases. One view is that some procedure of
the surgeon has set up a reflex inhibition of the heart through the
vagus; another, that the reflex has taken the form of sudden vasomotor
paresis. Levy would ascribe the condition to cardiac fibrillation.
It may well be that all cases cannot be met by one explanation. The
older surgeons stoutly maintained that reflex syncope could not arise
if the patient were properly under, and that it was in the practice
of those anæsthetists who were afraid of pushing the anæsthetic
sufficiently, that such accidents occurred. The author’s own belief
is that a _very_ light chloroform anæsthesia does pre-dispose to
this accident, but that it may occur also at a deep, the very deepest
possible level. With an anæsthetic other than chloroform, it is
extremely rare--perhaps unknown.
Treatment of Syncope.
This must be speedy to be of any avail. The following are the points
upon which to concentrate:--
(1) _Withdraw the anæsthetic._
(2) Make sure that the _air way is free_.
(3) Begin _artificial respiration_ by Sylvester’s method, the
movement of _expiration_ being first performed (_see_ Fig. 48).
(4) _Lowering of the head and shoulders_ is usually to be
recommended. It is best done by tilting the whole table as if
for the Trendelenberg position.
The lowering of the head attracts more blood to the carotid
artery and raises the blood pressure of the main vessel and
its cerebral branches (_see_ Fig. 35). It must, however, be
remembered that it will also tend to empty the blood in the
veins of the lower extremities and abdomen into the right side
of the heart, and cases in which marked cyanosis has preceded
pallor, are probably suffering already from engorgement and
dilatation of the right heart. The tilting of the table should
in such cases be very moderate in degree, and should not be
persisted in if it seems to do no good. In no case, indeed,
should the tilting be extreme. An angle of more than 15 or 20
degrees is as likely to do harm as good.
[Illustration: FIG. 48A.--Artificial respiration by
Sylvester’s method. Expiration.]
(5) Hot cloths may be placed over the precordial region, care
being taken not to burn the skin.
(6) The only _drugs_ likely to be of any avail are atropine and
strychnine, the former being used with the idea of paralysing
the terminations of the vagus in the heart muscle, the latter as
a cardiac tonic and a stimulant to the respiratory centre. Some
authorities have recommended the injection of atropine by a long
needle passed into the heart muscle, but most are content to
give either or both drugs hypodermically. Really to paralyse the
vagus, a very large dose of atropine is required--about ¹⁄₃₀ gr.
Strychnine should be given in a dose of ¹⁄₄₀–¹⁄₃₀ gr.
[Illustration: FIG. 48B.--Artificial respiration by
Sylvester’s method. Inspiration.]
(7) In cases where the right heart has certainly been
over-distended, the expedient of venesection has been tried.
Some six ounces may be withdrawn from the external jugular or
one of the veins of the arm.
(8) As a last resort, _the heart may be massaged_. The only
practicable route is to open the abdomen (if not already done)
pass one hand under the left side of the vault of the diaphragm,
placing the other hand over the precordial region. Between the
two hands, the heart can first be thoroughly compressed to empty
its presumably flaccid and over-distended cavities, and then
lightly massaged. Several cases of recovery from this measure
are on record.
Status Lymphaticus.
Before leaving the subject of accidents it may be well to allude
to this condition, which is also known as status thymicus, and as
lymphatism.
It is met with mostly in the young, the commonest ages probably being
five to fifteen years. Certain pathological conditions have been found
in fatal cases, of which the most important are an enlargement of the
thymus gland, of various lymph glands, and of the tonsils, including
the naso-pharyngeal tonsil (adenoids). The heart muscle is frequently
degenerated. Of the cause of these abnormalities we are as yet in
doubt. There is some reason to believe that the condition tends to
disappear with advancing years, if the subject survive.
The most outstanding clinical fact in connection with the disease
is its tendency to cause sudden death on very little provocation. A
fright, a sudden exertion, and above all an anæsthetic may cause sudden
and fatal syncope.
DIAGNOSIS.
Suspicion that the disease is present may be aroused in several ways.
The presence of enlarged tonsils and adenoids, combined with general
enlargement of lymph glands from no obvious cause, and a tendency
to faint, make a very suggestive picture. “Night-crowing” (a sudden
attack of laryngeal spasm, occurring at night, and often repeated
at intervals) also raises grave doubt. The diagnosis can only be
established with certainty by an X-ray photograph, when the great
enlargement of the thymus may be seen in the upper part of the chest.
ANÆSTHETICS IN STATUS LYMPHATICUS.
Too frequently the condition has never been suspected, and a fatality
occurs from sudden syncope, usually during the induction period, but
occasionally during the progress of the operation. It would, however,
be fallacious to suppose that an anæsthetic is necessarily fatal even
to an undoubted case. If the drug (preferably ether) be given with
great care, and the operation done carefully at a level of anæsthesia
neither too light nor too deep, there is every reason to believe that
the danger can be, and often is, successfully averted.
At the same time, it must be understood that in a known case, operation
should always be avoided or deferred if possible.
CHAPTER XVII.
THE SEQUELÆ OF ANÆSTHESIA.
Respiratory System.
After operations performed under any form of anæsthesia, even spinal,
there is always a possibility of pneumonia or bronchitis. The
anæsthetic itself is not always to blame. The patient has suffered
trauma and is confined to bed, and may develop a hypostatic pneumonia
just as a person who has suffered from a fractured thigh so commonly
does, even though he has had no anæsthetic at all.
It is probable that organisms, capable under certain circumstances of
causing inflammatory disease of the respiratory tract, are present
in a large proportion of apparently healthy people. Pneumococci and
streptococci of varying strains may be grown from nasal or pharyngeal
secretions of patients who suffer from catarrh of these regions, and
may reappear upon slight provocation even when prolonged treatment had
apparently banished them permanently. All that is required to start
an acute infection of lungs or bronchi, is some factor that depresses
vitality and lowers body resistance to the organism. And if in addition
use has been made of an inhalational anæsthetic such as ether, which
may cause an immediate and fairly acute congestion of the respiratory
mucous membranes, it is not to be wondered at that serious sequelæ
follow in a certain proportion of cases.
Laboratory results go to show that ether lowers the opsonic index
of the blood to pneumococci and streptococci, but without placing
undue emphasis upon a mere isolated phenomenon such as that, it is
plain that the whole conditions of the patient after operation are
favourable to the occurrence of pneumonia or bronchitis, and that of
all anæsthetics ether is the most likely to be the determining factor.
Experience gained during the war has thrown a certain amount of light
upon this subject. Post-anæsthetic bronchitis and pneumonia was
very prevalent among the wounded, far more so than among civilian
patients. It is, the author believes, reasonable to attribute this
fact to several causes. In the first place, the soldier’s life,
alternating between stuffy billets and wet trenches, predisposed him
to naso-pharyngeal catarrh of a fairly high degree of infectivity.
Enthusiastic press representatives might state that you could not take
cold so long as your feet and legs were always buried in half frozen
mud, but experience hardly bore out their golden promises. Again, the
soldier did not improve his catarrh by inveterate cigarette smoking.
Lastly, military hospitals were large institutions, some under canvas,
some in huts, some in buildings constructed for other purposes, and
rapidly altered to the urgent needs of the army. Of whatever type,
nearly all had one feature in common--many of the surgical wards were a
long (and draughty) way from the operating theatre.
For the prevention of post-anæsthetic pneumonia, the author offers the
following tentative suggestions:--
(1) See that the skin is kept covered up as much as possible
during the operation and that the patient is not exposed to
draughts during or after it. Rooms can, and should be, well
ventilated without cold draughts.
(2) If a patient has an acute or sub-acute naso-pharyngeal
catarrh, treat it as fully as possible before operation by
sprays and gargles.
(3) Do not use ether to patients who suffer or recently have
suffered from such conditions.
(4) Give a hypodermic of morphia and atropine before operation
as a routine.
(5) In so far as possible, let the patient’s shoulders and head
be raised by pillows during the early hours of convalescence.
(6) Lastly, remember that while no care will absolutely banish
these dangerous sequelæ from our practice, the greater care
and skill shown by the anæsthetist, the less bronchitis and
pneumonia will appear among his patients. As regards ether, the
author believes that it is the strength of vapour used, more
than the duration of the anæsthesia, which counts. It is for
that, among other reasons, that he has for the induction period,
no hesitation in recommending a method whereby a small part of
the requisite ether strength is replaced by chloroform.
Vomiting.
After an anæsthesia lasting more than a few minutes, it may almost be
regarded as normal for the patient to vomit once or twice. Usually this
occurs a few minutes after the administration has ceased. In the case
of nitrous oxide and oxygen, even this slight disturbance may not occur.
The amount of vomiting which after this stage may be regarded as
normal is difficult to determine. The author took notes of some 300
cases on this point. The details of his results are not suitable for
a text book, but, broadly speaking, it would appear that after an
operation of ordinary duration and severity, the vomiting returns on
the average some five or six times, and usually ceases on the evening
of the operation day. A limited number continue to vomit at intervals
until the early hours of the following morning. With nitrous oxide
and oxygen the vomiting is far less than the above, though even with
this anæsthetic quite severe emesis may occur. With closed-ether, the
trouble is very violent for a short time, large quantities of mucous
being ejected: it is probable that after the first two hours, it is no
more marked than after open methods. The use of morphia and atropine
before operation most certainly reduces the violence and duration of
this sequela.
Prolonged more than twenty-four hours, the condition must be regarded
as definitely abnormal.
PREVENTION AND TREATMENT.
The adoption of open-ether preceded by morphia and atropine and due
skill and thought on the part of the anæsthetist, combined with proper
preparation of the patient, are the only means of prevention at our
command.
The raised position of the head and shoulders during the recovery
stage undoubtedly tends to reduce the nuisance. It is a vexed question
whether to give or to withhold fluids after operation--and this matter
is of course in the hands of the surgeon, not the anæsthetist. In
certain cases, the author believes that it is worth while trying the
effect of a cup of fresh tea with very little sugar or milk. Even if
rejected in a few moments, the astringent effect of the infusion seems
to soothe the gastric mucous membrane, and give relief.
Post-operative Acidosis.
(Synonym--Delayed Chloroform Poisoning).
In a limited number of cases, post-operative emesis assumes a grave
type, and definitely threatens life. Such cases began to be studied
in the early part of this century, and though our knowledge of the
condition is still incomplete, the student should be acquainted with
the present views held upon the subject.
Clinically, the earliest symptom to raise suspicion, is the
reappearance of vomiting at a time when one would expect such trouble
to have abated, usually twenty-four or thirty-six hours after
operation. Within a few hours, the nature of the vomit changes from
the usual bilious stomach contents, and shows obvious evidence of
the presence of _altered blood_. The pulse and temperature begin to
rise, the countenance assumes an anxious look. A trace of jaundice is
usually present. The nervous system becomes affected as shown first in
restlessness, and later, delirium. Every degree of this condition is
possible, but a very large proportion of recognisable cases pass into
coma, and death supervenes within a few days, sometimes less.
Investigation into such cases has shown that the essential underlying
condition is an acidosis closely allied to that seen in diabetic coma.
The breath has the peculiar sweetish aroma of acetone, and acetone,
diacetic acid, and B. oxybutyric acid successively appear in the urine.
Post-mortem, the most striking change found is a profound fatty
degeneration of the liver, the cells of which are disintegrated as in
acute yellow atrophy.
It is obvious from the foregoing that there is present a very
remarkable abnormality of metabolism. Mr Rendle Short, in his admirable
book, _The New Physiology in Surgical and General Practice_, gives
the following explanation of the condition:--
“The physiological process of dealing with fat is to resolve it into
carbon di-oxide and water. If we make a pound of fat into tallow
candles and burn it, we shall obtain carbon di-oxide and water, and a
certain amount of heat will be evolved. If the pound of fat is eaten
and absorbed by a man or an animal, it will be burnt to the same end
products, and the same amount of heat will be given out. But in certain
circumstances, an abnormal mode of breaking down is followed, and
there are produced, first B. oxybutyric acid, then diacetic acid, and
finally acetone. If this takes place on a large scale, the conversion
into acetone fails to keep pace with the production of acids. Therefore
first acetone appears in the urine, then diacetic acid, and finally
oxybutyric acid; the last may rise rapidly to an enormous figure: 30,
50, or even 180 grams may be passed daily.”
Later in the same chapter, Short propounds the question as to what are
the special circumstances in which the breaking down of fat deviates
from its normal course, and follows this dangerous route. The answer
is, he says, quite definite and decisive. When the tissues are unable
to obtain sugar from the blood, fat is broken down _via_ these
dangerous acids to acetone, instead of to carbon di-oxide and water.
Such an inability on the part of the tissues to obtain sugar arises
under several conditions:--
(_a_) In diabetes, where sugar though freely present in
the blood cannot, for some reason still not clearly known, be
assimilated by the tissues.
(_b_) In poisoning by salicylates.
(_c_) In starvation, for obvious reasons. The supply of sugar
from the liver has been used up, and the patient, living on his
own fats, breaks them up abnormally.
(_d_) In post-anæsthetic poisoning, for reasons which are
at present not clearly ascertained.
Upon the theoretical side it is therefore not possible to say more than
that anæsthetics sometimes initiate this abnormal metabolic process. To
the question as to why and how they do so, we can as yet give no answer.
Upon the practical side, we can, however, speak much more definitely.
Acidosis follows the use of ether very rarely indeed: after nitrous
oxide it is unknown. Chloroform has been the drug used in almost every
recorded case, while ethyl chloride has been responsible in a few
isolated instances. Young children are much more prone to suffer than
adults, though the author had a fatal case in a lady well over forty
years of age: he has also seen a case very nearly fatal in a soldier
aged twenty. This man was, a week after recovery from acidosis,
anæsthetised for half-an-hour with nitrous oxide and oxygen, without
exhibiting any signs of a return of his dangerous condition. Anæsthesia
repeated in the same subject after a short interval is more prone
to start the process than a first inhalation. Lastly, acute sepsis,
particularly in the young, is notorious for its liability to be
followed by acidosis.
PREVENTION AND TREATMENT.
The obvious moral of the foregoing is that chloroform should not be
administered to patients suffering from acute sepsis, particularly if
they be very young. Indeed, so common is a mild degree of acidosis
among children, some surgeons consider there is a definite risk in
giving chloroform to them at all unless special precautions are taken.
Chief among these are regular dosage for a day or two before operation,
with considerable doses of bicarbonate of soda and sugar, which is a
routine measure in some children’s hospitals.
As regards curative treatment, much can be done if the gravity of the
condition is recognised early. The stomach is first washed out with
alkalis, and a substantial dose (one dram) of bicarbonate of soda left
in it. The same dose is repeated hourly by the mouth, if retained, or
per rectum. A useful addition to the alkaline treatment is dextrose,
also in teaspoonful doses. In grave cases, these drugs should be given
intravenously in saline solution.
These measures combined with warmth, and ample fluids by mouth or
rectum, will often save life, but to be of any value they must be
begun early. Fulminating cases occur which succumb rapidly in spite of
treatment.
CHAPTER XVIII.
POSTURE OF THE PATIENT.
The position in which the patient is lying is of as much importance to
the anæsthetist as to the surgeon. It is for the surgeon to say what
he wants and for the anæsthetist to realise how his own work will be
thereby affected.
Dorsal Decubities.
This is the ordinary position and calls for no extended comment. The
pillows must be so arranged that at no spot is the body acutely flexed
or extended. Abdomen, thorax, neck, and head must all be roughly in a
straight line.
Deep-chested subjects require a higher pillow than those with shallow
chests, otherwise the neck is bent back and respiration obstructed.
The arms should either be folded and retained by a bandage or other
device over the chest, or extended so that the hands can be slipped
under the buttocks and retained there by the body weight. An arm which
is allowed to hang over the side of the table is likely to show next
day and for many months afterwards, the condition of drop-wrist from
musculo-spiral paralysis.
Face-down Position.
This is an awkward position for the anæsthetist; there being a general
tendency to respiratory embarrassment. Put a pillow under the upper
part of the thorax, leaving the lower part and the abdomen as free as
possible. Let the head project from the pillow, so that the face can be
got at without undue rotation of the neck. The intratracheal method is
a great help.
Lateral Position.
This may be called for either with or without the addition of a
sand-bag or inflatable air-pillow to push the loin upwards. In either
case, there is a tendency for the upper shoulder to fall forwards, the
position then assimilating itself to the face-down position. This is
best met by a support fixed to the table, upon which the upper arm may
be rested. Failing such a convenience, a sand-bag may be pushed in to
keep up the shoulder, or the assistance of a nurse may be required.
The Trendelenburg Position.
Slight tilting of the head end of the table downwards is often useful
in assisting the return of bowel into the abdomen: in this position,
the patient usually takes the anæsthetic very well. It must not be
assumed until the third stage of anæsthesia is reached.
For many gynæcological operations, however, the full Trendelenburg
position is required. Healthy subjects usually do quite well in it, but
stout persons not uncommonly show a good deal of cyanosis. At the close
of the operation it is essential to restore the table to the horizontal
_slowly_: the physics of the circulation are profoundly modified,
and if any serious degree of shock is present, rapid return to normal
may initiate a collapse.
In the full position, the weight of the body should be taken by metal
supports attached to the table against which the shoulders may rest. To
hang the entire weight of the body upon the legs may cause a good deal
of after-suffering to the patient.
The Sitting-up Position. (_See_ Fig. 49.)
The object of this position is to diminish venous engorgement and
bleeding in operations requiring delicate dissection in the region of
the neck. Prof. Alexis Thomson introduced the position into Edinburgh
surgery: the author was at first rather nervous of it, but has found
that with proper precautions the patients do uncommonly well. Beyond
all doubt, the position is a great help to the work of the surgeon.
Not every surgical table is capable of giving the full position without
the use of many pillows and sandbags. The head-piece of the table is
tilted up at an angle of about 75° or even 80°, and the patient pulled
up so that the flexion of the body occurs in the lumbar, not the dorsal
spine. A small sand-pillow is placed behind the neck so as to produce
slight extension. Another heavier one is placed under the thighs to
prevent the body slipping down. A slight tilt downwards towards the
head end may be given to the table as a whole with the same object.
[Illustration: FIG. 49.--Sitting-up posture for operations
on the neck.]
One should not in this position attempt to induce a deep chloroform
anæsthesia. Weak C.E. mixture at most, but better simply open-ether is
the method of choice. The induction is begun with the shoulders raised
to a modified degree, and the full position assumed in a light third
stage anæsthesia.
Intratracheal ether combined with this position is an ideal anæsthesia
for the removal of goitre or extensive dissections in the neck for
enlarged glands.
O’Malley’s Position for Nasal Surgery. (_See_ Fig. 50).
The author became acquainted with this useful position while acting as
Anæsthetist at the Royal Herbert Hospital, Woolwich, where the Nose
and Throat Department was under the charge of Major O’Malley, F.R.C.S.
Major O’Malley was kind enough in a recent letter written by request to
refresh the author’s memory of the details.
[Illustration: FIG. 50.--O’Malley’s posture for
intra-nasal surgery.]
With the patient lying as shewn in the photograph, every part of the
interior of the nose can be easily inspected by the surgeon; the
elevation of the head and shoulders prevents undue bleeding, and
such hæmorrhage as does occur goes down the gullet, where it does no
particular harm, instead of into the larynx. The degree of flexion
of the head upon the neck is not so extreme as to interfere with
respiration.
The details of O’Malley’s procedure are as follows:--
The interior of the nasal cavities are packed with gauze soaked in
adrenalin and novocain a quarter of an hour before operation, and the
patient receives a very small dose of morphia and atropine immediately
before anæsthesis is induced; given in this way it does not complicate
the induction with chloroform to the same extent as if given earlier.
The patient lies with the top of the head level with the top of the
table, and the head and shoulders (including the upper two-thirds of
the shoulder blades) supported on the usual depth of pillow. Induction
is by chloroform or mixture; a very light third stage only is aimed
at. When it is attained the mouth is opened by a gag, and Phillip’s
Oral Airway inserted (_see_ Fig. 8). Strict oral respiration is
essential to success. If air is passing in and out of the nose, blood
is spluttered all over the surgeon, seriously interfering with the
harmony of the proceedings. Junker’s chloroform bottle is ready, and
the end of the supply pipe is passed into one of the side holes in the
air way.
The head of the table is now elevated to an angle of 45°, and a small
sand pillow slipped behind the occiput. The gauze is removed from the
nose, and the operation can be performed with great comfort.
The circulation of the patient needs careful watching for the first
minute or two after the table head has been elevated, but thereafter
there is usually no special cause for anxiety. The area of operation
is locally anæsthetised by the action of the novocain and a light
chloroform sleep only is required.
CHAPTER XIX.
CHOICE OF ANÆSTHETIC.
In considering this matter, some repetition of points to which
reference has already been made, is inevitable. Indeed, this chapter
may be regarded as a revision of the whole subject.
Before deciding upon drug and method suitable for the individual case,
we must consider the age and sex, the physical type and temperament,
the possible presence of some definite pathological condition, and the
nature and duration of the operation.
In relation to this last point, we must remember that an anæsthesia
must be adequate to the purpose of the surgeon, but that it is improper
to incur more risk to life than is necessary. For instance, an
abdominal section case must be fully relaxed, and if in an individual
case, chloroform is the only drug which will give that effect, there
need be no hesitation in using it. On the other hand, many other
methods with a far smaller mortality rate are available if all that is
required is the extraction of a tooth or the incision of an abscess,
and in that group of cases, unfamiliarity with such anæsthetics as
nitrous oxide or “ethyl chloride and ether” will not be held as a
sufficient defence if chloroform has been given with a fatal effect.
Normal Subjects.
Let us take first the case of the healthy adult about to undergo a
_major_ operation. For this, we unhesitatingly choose what we may term
the “stock” method--open-ether preceded by morphia and atropine.
If the operation be _brief_, we have a choice of methods. For the
extraction of teeth, where access to the mouth is essential, the
following table will help:--
+------------------------+---------------------------+-------------------------+
| |Duration of Available | |
|ANÆSTHETIC DRUG AND | Anæsthesia, when | REMARKS. |
|METHOD. | given as “Single | |
| | Dose.” | |
+------------------------+---------------------------+-------------------------+
|Nitrous oxide |30 to 40 seconds | |
|Nitrous oxide and |40 to 50 seconds | |
| oxygen | | |
|Ethyl chloride |70 to 90 seconds |Only to be recommended |
| | | in special cases (_see_|
| | | page 127). |
|Gas and ethyl chloride |70 to 90 seconds | |
|Gas-oxygen and ethyl |70 to 90 seconds | |
| chloride | | |
|Gas and ether |Anything up to 2 to 5 |May cause after vomiting.|
| | minutes according to | |
| | duration of inhalation | |
|Ethyl chloride and ether|Anything up to 2 to 5 |May cause after vomiting.|
| | minutes according to | More portable. |
| | duration of inhalation | |
|Nasal gas |5 to 10 minutes (not a |Requires considerable |
| | “single dose” anæsthetic)| practice to give well. |
|Nasal gas and oxygen |No limit |Easier to give than |
| | | above but apparatus |
| | | rather importable. |
+------------------------+---------------------------+-------------------------+
In cases where access to the mouth is not required, and where it is
therefore unnecessary to “charge up” the patient with anæsthetic, we
have also a choice which may be expressed tabularly:--
+------------------------+-----------------------------------------------------+
| ANÆSTHETIC. | REMARKS. |
+------------------------+-----------------------------------------------------+
|Nitrous oxide |Apparatus simple: short administration can be |
| | mastered easily. A little more practice required |
| | for cases prolonged by admitting air. Muscles |
| | not relaxed, and patient may move when cut. |
| | |
|Nitrous oxide and |Apparatus more complicated, but short administrations|
| oxygen | present no great difficulty to the beginner. |
| | Muscles not completely relaxed unless a little |
| | ether added. |
| | |
|Gas and ether |Quick and safe anæsthetic. Deep anæsthesia |
| | may be obtained if ether is “pushed.” |
| | |
|Ethyl chloride and ether|The same. More portable than above. |
+------------------------+-----------------------------------------------------+
In this group of short operations, special reference must be made to
the _reduction of dislocations_. Here two important features
require notice. The whole object of the proceeding is to relax muscles,
and therefore nitrous oxide or gas-oxygen are unsuitable. Secondly,
the tendency to reflex syncope just at the moment of reduction is very
great. For this reason, chloroform has here a painfully high mortality
rate; closed-ether, preceded by gas or ethyl chloride, is undoubtedly
the method of choice.
The Extremes of Age.
Children up to the age of ten years take ether badly, salivation
and bronchial secretion being sometimes very troublesome. Atropine
mitigates this nuisance to a limited degree only. Chloroform is the
best drug up to five or six years; from five to ten, mixture; after
that, open ether.
In children of any age, suffering from acute sepsis, the immediate
annoyances and possible respiratory sequelæ of ether must be faced
(_see_ page 156), owing to the probability of acidosis.
As regards short anæsthetics in children, nitrous oxide, if given at
all, should be freely diluted with oxygen, otherwise most undesirable
cyanosis will occur. To children under three or four, even gas-oxygen
is of doubtful safety. Short anæsthesias in such cases may be induced
by open ethyl chloride, with a few drops of ether added.
Old people are, unless very feeble, best anæsthetised by a mixture of
chloroform and ether. Whatever anæsthetic be chosen, the utmost care
must be taken to avoid cyanosis. A cylinder of oxygen should be at hand
from which to enrich the atmosphere breathed, by trickling the gas into
the mouth through a rubber tube, and is a great safeguard in dealing
with the old.
Sex.
On the average, women take anæsthetics much better than men, being far
less liable to jaw clenching and other forms of mechanical asphyxia,
and showing less excitement during the induction stage. In the female
subject induction by open-ether requires very little assistance from
C.E. mixture.
Physical Type and Temperament, and Habits of Life.
Heavily built muscular men are troublesome subjects. Induction requires
a rather strong vapour of ether: if the open method is used, there may
be to the beginner much temptation to make use during the induction
stage of C.E. mixture to an extent not contemplated in the description
given of that method in chapter IX.: it is therefore wise to induce
either with closed-ether or with C.E. mixture as described in chapter
XV., and to change to the perhalation method only when full anæsthesia
is attained.
As regards alcoholics and excessive smokers, these are well dealt with
by the C.E. open-ether sequence. Recourse may be made to the Ormsby
inhaler as already explained on page 137. The reader is warned not to
be deceived by the stout, rosy face of the typical alcoholic. He often
looks a great deal stronger than he really is. Many such are really
feeble subjects: although they shout and struggle no great addition
to the usual vapour strength of anæsthetic is safe or required: what
_is_ required, is a little extra time. Once fully under, the robust
appearance of the patient disappears, and the fact that one is dealing
with a rather broken constitution and a poor circulation is obvious.
Reference has already been made to the fact that persons with defective
nervous systems, neurotics, and especially epileptics, show persistence
of some muscular movements for some time, and therefore require very
careful watching.
Special Operations and Pathological Conditions in the Patient.
These are of the utmost importance, but to consider each fully from
the anæsthetic point of view, would lead us into great detail. The
anæsthetist must acquaint himself with any abnormality present, and
consider it carefully in the light of the general principles already
explained. The following very brief hints for selected cases and
operations may, however, be found useful.
UPPER AIR PASSAGES.
_Artificial teeth._ Must be removed before inducing.
_Tongue and jaw cases._--Intratracheal ether the best--failing that,
rectal oil ether, or Junker’s inhaler.
_Nasal operations._--If adrenalin is to be used, it must precede,
not follow, chloroform--many fatalities have occurred from injecting
or even packing with adrenalin in light chloroform narcosis. Some
surgeons object to ether because of the bleeding, but this can be
largely remedied by raising the head and shoulders, and by packing with
adrenalin. Many surgeons prefer local to general anæsthesia.
_Nasal insufficiency._--Don’t allow a patient to continue to make
ineffectual attempts to breathe through a narrow nose. Establish mouth
breathing, or use Silk’s tubes (_see_ Fig. 9).
_Tonsils and adenoids._--Give ethyl chloride by the vapour method.
_Tumours and inflammatory swellings obstructing respiration._--
Don’t use closed methods. Have tracheotomy instruments at hand, and a
cylinder of oxygen.
_Gôitres, especially exophthalmic gôitre._--Don’t use chloroform: it
has caused many fatalities; morph-atropine, followed by open-ether is
the safest. In bad cases, use rectal oil ether if intratracheal is not
available. The “sitting up posture” is a great help (_see_ page 168).
Use anoci-association if surgeon is willing.
CHEST.
_Bronchitis and pneumonia_ (_see_ remarks in chapter XVII).
_Emphysema and rigid chest wall._--Patients take anæsthetics badly;
they cyanose quickly, the abdominal wall cannot be made either lax or
quiet, since the patient’s natural method of respiration is abdominal
rather than thoracic. Lastly, there is frequently a dilated heart with
degenerate cardiac muscle, giving an abnormal tendency to secondary
syncope. Give a trickle of oxygen through a tube from a cylinder: don’t
be tempted to overdose with anæsthetic in the vain hope of securing
ideal relaxation of the abdominal wall.
_Empyæma._--Be careful: a good many accidents have happened. Use
chloroform with added oxygen: aim at an anæsthesia just deep enough
to prevent straining which might rupture the empyæma into the lung
and drown him in his own pus. Withdraw the anæsthetic as soon as the
abscess is opened.
_Phthisis._--Don’t use closed-ether: it may start
hæmorrhage--open-ether rarely does any harm unless the condition is
very acute.
CIRCULATORY SYSTEM.
_High tension, arterio-sclerosis, and aneurysm._--Avoid pure
nitrous oxide: in severe cases, C.E. mixture and oxygen is the safest.
_Heart._--Well compensated cases of _valvular disease_
take chloroform or open-ether well, provided a free air-way is
maintained. Closed methods should be avoided. Cases of _myocardial
disease_ with dilated cavities present special dangers. Open-ether
with added oxygen meets the case better than any other anæsthetic.
_Pericarditis_, both acute and chronic, has been found as the
determining factor in many anæsthetic fatalities.
ACUTE INFECTIOUS DISEASE.
_Febrile patients_ absorb anæsthetics very rapidly and therefore
go under very quickly. Acute septic cases must not have chloroform
or ethyl chloride (_see_ page 155): nitrous oxide and oxygen is
ideal, ether the next best. Patients who have suffered from acute
infectious disease, especially diphtheria and influenza, may present
some weakness of heart muscle for many months after the attack.
EXHAUSTED AND SHOCKED CASES.
Give nitrous oxide and oxygen if possible--failing that, ether.
Closed-ether sometimes does very well for the induction stage.
DIABETES.
Chloroform is wholly inadmissible.
GENITO-URINARY SYSTEM.
_Kidneys._--Avoid ether in acute or sub-acute nephritis: give it,
however, for nephrectomy when the other kidney is sound.
_Bladder._--Distending the bladder with lotion often causes reflex
inhibition of respiration: if that happens, stop the anæsthetic, give
artificial respiration, and ask the surgeon to get on with opening the
bladder. _Morphia_ usually arrests temporarily the secretion of urine:
it should therefore not be given if chromocystoscopy or catheterisation
of the ureters is contemplated.
_Prostatectomy cases_ are often rather broken subjects: give a fairly
deep anæsthesia until the shelling out of the prostate is begun: then
be careful--the patient is breathing deeply as a rule, and can readily
get an overdose. He will inevitably suffer a fair amount of shock:
be ready to lower the table at the head end if any serious collapse
occurs. Don’t be shy of starting a little artificial respiration even
though the natural function is not entirely abolished.
_Circumcision_ usually causes a good deal of laryngeal spasm,
especially in children. Don’t try to abolish this by deepening the
anæsthesia. You won’t succeed unless you nearly kill the patient. Rub
the lips, and if very severe ask the surgeon to stop a minute until the
crowing becomes less.
_Castration._--Always give ether, or gas-oxygen. Castration and
reduction of dislocation are the two commonest causes of reflex syncope
under chloroform.
MENSTRUATION, PREGNANCY, AND LABOUR.
It is usual to avoid anæsthetics during the menstrual period if
possible, the nervous system being unlikely to be at its best at that
time.
Pregnant patients take no harm from an anæsthetic properly given,
but undue cyanosis must be avoided or abortion may occur. The pains
of labour may be alleviated by chloroform given to an early second
stage only, or by “twilight sleep” (_see_ page 44). For the major
operations of obstetrics, however, ether has its usual advantages,
provided no bronchitis be present. The shock of such operations as a
difficult version is considerable, and quite sufficient to call for
ether rather than chloroform.
_Indication for Local and Spinal Anæsthesia._--The foregoing has
been written in reference to inhalational anæsthesia solely. Mr
Wood has indicated in chapters XX. and XXI. the class of case in
which the methods he describes are to be preferred.
CHAPTER XX.
LOCAL ANÆSTHESIA.
By the term local anæsthesia, or more correctly _local analgesia_,
is meant the loss of sensibility to painful stimuli without loss of
general consciousness. It may be induced in a considerable number
of ways, but for practical purposes there are only four methods of
value:--(1) by infiltration of the tissues to be operated upon by a
solution of the drug, (2) by injecting the solution into or around
the nerve trunks supplying the part, (3) by painting the solution on
a mucous surface, and (4) by the application of intense cold. The
last method has only a limited application. The method of injecting
the anæsthetic into the blood vessels of the part is still in the
experimental stage and is not to be recommended for general use.
It is advisable first to consider the behaviour of the principal drugs
which are employed.
Cocaine.
This was the first drug to be widely used for the production of
local anæsthesia. It is an alkaloid occurring in the leaves of
_Erythroxylon Coca_. It is only slightly soluble in water--about
1 in 1300, but the hydrochloride of cocaine is freely soluble, and it
is this salt that is commonly used for aqueous solutions. The solutions
do not keep well, and should be made up shortly before being used. The
drug is decomposed by boiling.
ACTION.--When a solution of cocaine is injected into the tissues,
the sensory nerve endings become anæsthetic over the area into which
the drug penetrates, direct paralysis of the nerve terminals being
produced. When it is injected into or around a nerve trunk it blocks
the transmission of nerve impulses. When it is applied locally to a
mucous membrane, it produces, besides a loss of sensation, a feeling
of constriction and a distinct pallor and contraction of the vessels,
which point to a local action on the vessel walls. The drug is very
frequently applied to the eye. There it produces not only local
anæsthesia, but also contraction of the conjunctival vessels, and this
is followed by dilatation of the pupil and often by partial loss of the
power of accommodation.
COCAINE POISONING.--Certain patients show an idiosyncrasy to the
action of cocaine, and the greatest care must be exercised in its use.
Absorption of small quantities usually causes mental excitement. The
patient becomes restless and garrulous, and a feeling of happiness
may be produced, but in other cases the patient becomes anxious
and confused. In some patients a small dose is followed by a calm
languorous state, resembling that produced by morphia, but with less
tendency to sleep. The pulse is accelerated, the respiration is quick
and deep, and the pupils are dilated. When poisonous doses have been
administered, the heart becomes extremely accelerated, powerful tonic
or clonic convulsions supervene, the breathing becomes rapid and
shallow, and may be finally arrested during a convulsion. In some
cases a different set of symptoms are observed, fainting and collapse
occur, and convulsive seizures are almost entirely absent. The heart
is slow and and weak, the respirations are slow and shallow, the skin
is cyanotic and cold, and death takes place from gradual arrest of
respiration.
TREATMENT.--The treatment consists in endeavouring to encourage the
action of the heart by every possible means. The patient is placed
flat on his back, if he is not already in this position, hypodermic
injections of ether and strychnine are administered, and hot coffee
given by the mouth; warmth is of great importance. Artificial
respiration is commenced if respiration begins to fail. There is no
specific antidote to cocaine.
DOSAGE.--The maximum dose of cocaine that can be given with safety is
¾ of a grain. The amount of solution that may be employed depends
upon the strength. To make a 1 per cent solution, 1 gr. of cocaine
hydrochloride is dissolved in 110 minims of distilled water or half
strength normal saline; from these proportions the amount of cocaine
in a given solution can be calculated. It will be seen that the amount
of cocaine solution, even with strengths as weak as ½ or ¼ per cent,
that can be used with safety is small and insufficient to anæsthetise
an area of any great extent. Owing to its toxicity cocaine has largely
fallen out of use for the production of infiltration or regional
anæsthesia, though it is still widely used in ophthalmic surgery and in
the surgery of the ear, nose and throat.
Novocaine.
This drug is immensely superior to cocaine for ordinary surgical
purposes. It is the hydrochloride of a synthetic base, its chemical
formula being C_{13}H_{20}N_{2}O_{2}, HCl. It is soluble in water 1
in 1, and can be heated to 120°C without decomposition. Its solutions
possess slight antiseptic properties, and are capable of repeated
boiling without affecting their strength. They may be kept for several
months without suffering any change in their action, a quality not
possessed by any other anæsthetic agent.
The _toxicity_ of novocaine is one-fifth or one-seventh of that of
cocaine. When used in conjunction with adrenalin, its anæsthetic
activity is equal to that of cocaine. When injected into the tissues
it produces no irritant effects like certain other local anæsthetics,
notably stovaine. For the production of local anæsthesia it is used in
½ per cent. solution with the addition of three or four minims of 1 in
1000 solution of adrenalin chloride to each ounce. Several ounces of
this preparation may be used with the greatest safety.
Allen makes the following statement regarding this drug:--“After a
rather extended experience, including a large number of cases embracing
the entire field of surgery, in which this agent has been almost
exclusively used, we have failed to note a single case in which there
has been any unpleasant local or constitutional action. We, therefore,
feel thoroughly justified in unqualifiedly recommending it as the
safest, most reliable, and satisfactory of any local anæsthetic agent
yet introduced.”
Tropacocaine.
This drug was first isolated from the leaves of the coca plant of Java,
but is now prepared synthetically. Its formula is C_{15}H_{19}NO_{2}.
Its action is exactly the same as that of cocaine, except that it
is one-half as toxic and the duration of anæsthesia is shorter. The
hydrochloride is freely soluble in water, and can be boiled without
fear of decomposition. It is the agent which is most suitable for
spinal anæsthesia, as fewer unpleasant effects have followed its use
than that of any other drug.
Stovaine.
Stovaine is the hydrochloride of a synthetic compound of the benzoyl
group. It occurs as a white crystalline powder, soluble in water, 1 in
14. Its solutions withstand boiling, but are decomposed when heated
to 120°C. Its action is the same as that of cocaine, except that it
is slightly less toxic and less powerful. It has a distinct irritant
effect locally. When injected in dilute solution, it produces a slight
burning pain before anæsthesia appears, and very often a distinct
inflammatory reaction persists for some time after the operation. It is
therefore unsuited for local anæsthesia. It has been widely used for
the production of spinal anæsthesia, especially by the French school,
but since its injurious effects on nerve tissues have become more
apparent, it has been less used than formerly.
Eucaine.
Eucaine was introduced as a substitute for cocaine, and, before the
introduction of novocaine, was extensively used. It has a similar
action to cocaine, and although it is less toxic, it is by no means
free from danger unless it is used in very dilute solutions. It is a
vaso-dilator, and must therefore be used in combination with adrenalin.
It can be boiled without undergoing decomposition, and is practically
non-irritant. It has been largely superseded by novocaine.
Quinine and Urea Hydrochloride.
The use of this drug for purposes of local anæsthesia is still in the
experimental stage. It is made by adding urea to a solution of quinine
in hydrochloric acid. The crystals are soluble in their own weight of
water. For the production of local anæsthesia it is used in strengths
of ·25 to 1 per cent. It is free from toxic effects, and its solutions
can be sterilised by boiling.
The striking feature about this drug is the extraordinary duration of
the anæsthesia, this being from one to six days. It has therefore been
used by Crile and other American surgeons to prevent pain during the
first few days after operation. The great drawback to its use, however,
is that it causes a persistent indurated condition of the tissues which
interferes with primary union, and which is sometimes followed by
actual sloughing. In addition, it is now established that its use has
been followed by tetanus in several cases, and it is recommended that a
dose of antitetanic serum should be given immediately before or after
the injection of quinine.
Although the action of this drug is of great interest, it cannot be
recommended at present for ordinary purposes.
Adrenalin.
Adrenalin is obtained as an extract from the suprarenal glands of
animals. It is a greyish white powder, slightly soluble in water, and
readily so in weak acids. The usual preparation is a 1 in 1000 solution
of adrenalin chloride in normal saline. It contains ·5 per cent. of
chloroform as a preservative. The drawback to the animal extract is
that the solution does not keep well, decomposition being indicated by
a brownish colour. Of late a synthetic preparation has been introduced,
which appears to have the same action, and which can be sterilised by
boiling.
The action of the drug is to cause marked vaso-constriction by direct
action on the vessel walls. It has no analgesic action, and is used as
an addition to solutions of anæsthetic drugs. The advantages of its use
are that the action of the anæsthetic is concentrated and prolonged,
owing to the delay in absorption, and that the field of operation is
rendered practically bloodless. In large doses it may produce toxic
symptoms in the form of palpitations and breathlessness, or even actual
syncope, so that care is necessary in its use. For purposes of local
anæsthesia, it is added to the solution of the anæsthetic drug in the
strength of 3 drops to the ounce, and large injections of this dilute
solution may be made without risk. At least twenty drops may be safely
given.
Induction of Local Anæsthesia
Local anæsthesia may be induced by the use of anæsthetic drugs in three
ways--(1) infiltration anæsthesia, (2) regional anæsthesia, and (3) by
application to a mucous surface or to the surface of the eye.
INFILTRATION ANÆSTHESIA.--In this method anæsthesia is induced by
injection of the drug directly into the tissues to be operated upon.
This method acts by paralysing the sensory nerve-endings. Although
the term anæsthesia is constantly used, it is, strictly speaking,
an operative analgesia that is aimed at; it is a paralysis of the
pain-conducting fibres, and not of those which conduct purely tactile
sensations, the patient being often able to feel the contact of the
fingers and instruments during the operation. True anæsthesia can be
secured, but it is necessary to use considerably stronger solutions
than those that are required for the production of analgesia.
SOLUTION OF THE DRUG.--Novocaine is far superior to any other drug for
infiltration anæsthesia. The strength for most purposes is ½ per cent.,
though some operators find ¼ per cent. quite satisfactory. In specially
sensitive parts, such as the nose, throat, or mouth, 1 or even 2 per
cent. solutions may be preferable. Sufficient sodium chloride should
be added to prevent osmosis of the solution into the tissue cells. The
most satisfactory preparation is:--
Novocaine 0·25, 0·5, 1 or 2 (¼ to 2 percent.)
Normal salt solution (half 100·0 (·45 per cent. NaCl)
strength)
[Illustration: Fig. 51. All-Metal Syringe for Infiltration
Anæsthesia.]
Adrenalin is added to the solution in the proportion of 3 drops of 1 in
1000 adrenalin chloride to the ounce, and as much as 6 ounces of this
preparation may be safely given. The novocaine solution can be boiled
before use, but the adrenalin must not be added until after boiling.
For private practice it is sometimes convenient to procure the
novocaine in tabloid form of definite strength combined with sodium
chloride. These tabloids are added to the necessary amount of water,
and the whole boiled. The adrenalin can then be added.
CHOICE OF SYRINGE.--The best form of syringe for infiltration
anæsthesia is the all-metal syringe illustrated in Fig. 51. It ought
to have a capacity of at least 10 c.c. The advantage of the all-metal
syringe over glass syringes is that it can be safely sterilised by
boiling, and does not get broken. Between the syringe and the needle is
a metal segment which is curved so that the needle is set at an obtuse
angle to the syringe. This renders the infiltration of the tissues at
the proper depth much easier. The needles employed are the ordinary
hypodermic needles which are sold in small tubes. The sizes which
should be selected are 1 inch, and 3 or 3½ inches. The needle fits into
a hole in a small metal mount, which screws on to the intermediate
metal portion. This section also is attached to the syringe by a screw,
and these screw attachments have the advantage of rendering leakage
impossible.
Failing the syringe described, a 10 c.c. Record syringe will be found
to be quite efficient, if suitable needles can be obtained. The
syringe, needles, and glass measure for the solution should be boiled
in plain water or normal saline, as soda interferes with the action of
the drug.
TECHNIQUE OF INJECTION.--The needle is introduced into the
subcutaneous tissue, and pushed on slowly to its full length, the
fluid being injected as the needle advances. The needle is then partly
withdrawn, and pushed in in a different direction so as to infiltrate a
fresh area. This procedure is repeated, and as wide an area as possible
infiltrated from the one puncture. The needle can then be completely
withdrawn and introduced at a fresh point which has already been
rendered analgesic. The deeper tissues can nearly always be infiltrated
from the surface, but if large blood-vessels traverse the region to be
infiltrated, it may be necessary to defer the deeper injection until
these have been exposed. It is wise to infiltrate wide of the intended
line of the incision, since it is not possible to anticipate with
certainty the extent of an operation until it has been commenced. The
secret of successful anæsthesia is to employ plenty of the solution,
and make the injection thorough.
The skin over the area becomes blanched within a few minutes of the
injection owing to the action of the adrenalin. Anæsthesia is not
usually complete until ten minutes have elapsed, and the operation
should not be commenced until it has been made certain by suitable
tests that the anæsthesia is complete. The duration of the anæsthesia
is usually at least an hour and a half.
It will be seen that the injection in the manner described above is
entirely subcutaneous, the pain-conducting nerves from the skin being
caught up by the drug as they traverse the superficial fascia in the
area infiltrated. This method usually gives complete satisfaction,
but some surgeons advise that the infiltration should be commenced
with an _intra-dermal_ injection so as to reduce the pain of the
needle punctures to a minimum. A fine needle is employed, the prick
of which is practically painless. If the skin at the selected point
is pinched up between the finger and thumb, and held firmly, this
lessens its sensibility. The needle is advanced beneath the epidermis
with a quick but light thrust. The injection into the substance of the
skin causes a distinct wheal, which stands out from its surroundings
like an urticarial wheal. From this starting-point a long needle can
be introduced into the deeper tissues without pain. The intra-dermal
injection may be carried along the whole length of the area to be
infiltrated, each fresh puncture being made in the margin of the
wheal-like area already anæsthetised.
PRECAUTIONS.--The most careful asepsis is essential throughout.
Infiltration with novocaine causes no interference with the healing
of the wound, and although cases of sloughing of the tissues have been
reported after its use, these are almost certainly due to infection
of the wound. Care must be exercised also to avoid injecting the drug
into a vein. When this accident takes place, the drug is carried at
once into the general circulation, and may reach the higher nerve
centres in such quantity as to produce serious toxic results. The use
of adrenalin calls for special care and thoroughness in securing all
bleeding-points, as, after the effect of the adrenalin passes off,
even a slight ooze may increase and give rise to a hæmatoma which may
jeopardise the healing of the wound.
Regional Anæsthesia.
In this method of producing anæsthesia, the sensory nerve paths are
blocked by injecting the anæsthetic drug into, or around, a nerve
trunk. By this procedure complete anæsthesia is produced in the area of
distribution of the nerve, and the effect corresponds to a temporary
physiological section of the nerve trunk. A temporary motor paralysis
is also produced in a mixed nerve.
TECHNIQUE.--The solution of the drug must be stronger than that
employed for infiltration anæsthesia. A 2 per cent. solution of
novocaine in half-strength normal saline with the addition of adrenalin
is employed. The injection may be paraneural or intraneural.
A _paraneural_ injection is made by passing a needle through the
tissues to the known position of a nerve trunk and injecting the
anæsthetic around it. The solution gradually diffuses into the nerve
tissue, and anæsthesia of the nerve is produced. This method is open
to the objection that unless the anæsthetic is accurately placed, no
anæsthesia will result, and that in the case of certain nerves there is
considerable risk of making the injection into a vein. The latter risk
can be avoided by using a glassbarrelled syringe and applying a little
suction before the injection is made; if a vein has been pierced, blood
will enter the syringe.
The _intraneural_ method is more accurate but requires the expenditure
of considerable additional time and trouble, and is only employed
where other methods of anæsthesia are not feasible. The tissue over
the nerve having been infiltrated, the nerve is exposed by open
dissection. It must not be pinched by forceps or other instruments,
as such manipulations cause severe pain referred to its peripheral
distribution. The injection should be made with the nerve lying in its
bed by inserting a fine needle in the long axis of the nerve, first
into the sheath, which is infiltrated, and then into the nerve itself.
The infiltration of the nerve is continued until it presents a fusiform
swelling and this may require from 5 to 15 minims of the solution.
Complete anæsthesia of its entire distribution usually results in from
five to ten minutes.
A third method of inducing regional anæsthesia--first recommended by
Hackenbruch--which is worth mention, is by the production of a ring
of infiltration around a peripheral part, such as a finger, or around
and underneath a tumour. By this means the nerve fibres are caught up
by the anæsthetic and their conductivity interrupted as they enter the
area to be operated upon. In dealing with such conditions as a large
lipoma, or an umbilical hernia, it may be possible to avoid the use of
an excessive amount of anæsthetic solution by employing this method.
Methods of Application of Infiltration and Regional Anæsthesia.
It is sometimes stated that local anæsthesia should be limited to
small and superficial operations, but with a knowledge of anatomy and
of the correct technique, there are few operations which the surgeon
cannot undertake with this form of anæsthesia. If we remember that the
mortality from the anæsthetic is practically nil, it is obvious that it
is often the duty of the operator to give the patient the choice of
local anæsthesia. In urgent conditions in which the administration of a
general anæsthetic would be attended with great danger, it is often a
life-saving measure. Either infiltration or regional anæsthesia may be
used alone; in some cases it is convenient to combine the two methods.
Operations on the Upper Extremity.
Regional anæsthesia is sometimes employed in operations on the upper
extremity in conditions, such as diabetic gangrene or advanced cardiac
disease, where a general anæsthetic is contra-indicated. In similar
conditions in the lower extremity, spinal anæsthesia is usually
preferred, though it is quite possible to anæsthetise the lower limb
by blocking the sciatic, femoral, and lateral cutaneous nerves with a
local anæsthetic. Crile lays great stress on the blocking of nerves
with a local anæsthetic during operations on the limbs as a means of
preventing shock, even where a general anæsthetic is being employed.
The effect of the local anæsthetic is to prevent the impulses which
produce shock from passing up to the higher centres. Only those methods
which are applied to the upper extremity need special description.
ANÆSTHESIA OF THE WHOLE ARM.--The nerves of the upper extremity are all
derived from the brachial plexus except the intercosto-brachial. This
nerve, which is the lateral cutaneous branch of the second intercostal,
crosses the axilla and pierces the deep fascia on the medial side of
the arm. It supplies the skin on the dorsal part of the medial aspect
of the upper arm. The lateral cutaneous branch of the third intercostal
nerve sometimes crosses the axilla also, and reaches the medial
side of the arm. Injection of the brachial plexus produces complete
analgesia of the shoulder and entire arm, and is particularly suited
to high amputations and disarticulations at the shoulder. If the area
supplied by the intercosto-brachial is encroached upon, this can be
anæsthetised by infiltration with a few drams of solution injected
subcutaneously along the floor of the axilla from its lateral and
posterior borders.
METHOD.--The injection may be intraneural or paraneural. The
intraneural is made after exposing the plexus by an incision under
infiltration anæsthesia from the junction of the middle and lower
thirds of the sterno-mastoid to the union of the middle and lateral
thirds of the clavicle. It is found lying on the scalenus medius and
each of its branches is separately injected with a few drops of 5 per
cent. solution of novocaine containing a few drops of adrenalin to the
ounce.
The paraneural injection is less satisfactory, since the nerves
are too large to be readily penetrated in effective quantities by
the anæsthetic solution, and since there are numerous veins in the
neighbourhood into which the solution may be accidentally injected with
dangerous results.
The injection is usually made above the clavicle. In this region the
plexus lies mainly above and to the lateral side of the third part
of the subclavian artery, the lowest trunk lying directly behind the
vessel as it rests on the first rib. The position of the artery is
first localised with the finger by its pulsations, and the skin and
subcutaneous tissue infiltrated immediately above the mid-point of
the clavicle. From this point a long fine needle, unattached to the
syringe, is passed downwards, backwards, and medially in the direction
of the second or third thoracic spine. The distance to which the
needle penetrates varies from 2 to 4 c.m. When the plexus is reached a
slight radiating pain is felt down the distribution of the radial or
median nerve. At this point the needle is held stationary, the syringe
attached, and the injection made. The reason for not attaching the
syringe earlier is that should the artery be entered, blood will flow.
This accident is of little consequence, the needle being withdrawn
slightly and introduced a little more laterally. About 10 c.c. of a
2 per cent. solution of novocaine and adrenalin is injected; the
needle is then slightly withdrawn and a further 10 c.c. injected in the
neighbourhood. Anæsthesia occurs in from three to fifteen minutes.
[Illustration: FIG. 52.--Point at which the needle
is introduced in paraneural injection of brachial plexus.]
The individual nerves of the upper limb can be readily injected. The
_median_ can be exposed at the bend of the elbow for an intraneural
injection, or a needle may be passed under the tendon of the palmaris
longus at the wrist for a paraneural injection. The _ulnar_ can be
easily reached as it lies on the posterior aspect of the medial
epicondyle of the humerus for a paraneural or intraneural injection.
The _superficial radial_ can be reached for a paraneural injection
about two inches above the wrist to the lateral side of the tendon of
the brachio-radialis (supinator longus). The injection is made into the
deep fascia, and carried across the lateral border of the forearm for
about an inch, to ensure reaching all the branches of the nerve.
The _medial antibrachial_ (internal) _cutaneous_ can be blocked on
the front of elbow by a paraneural injection about half an inch
medial to the biceps tendon, and the _lateral antibrachial cutaneous_
(musculo-cutaneous) at a corresponding point on the other side of the
tendon.
ANÆSTHESIA OF THE ARM BELOW THE ELBOW.--In operations below the elbow,
in conditions in which a general anæsthetic is not permissible, as in
diabetes, nephritis or advanced cardiac disease, a full anæsthesia
can be obtained by intraneural injection of the median, ulnar, and
radial (musculo-spiral) nerves, combined with paraneural injection
of the medial and lateral antibrachial cutaneous. The median and
radial are each exposed by an incision under infiltration anæsthesia,
the radial being exposed in the groove between the brachialis and
brachio-radialis. The infiltration to expose the median nerve usually
blocks the anterior branch of the medial antibrachial cutaneous. To
make certain that the posterior branch is also anæsthetised, it is
advisable to inject a little anæsthetic solution over the front of the
medial epicondyle. The intraneural injection into the ulnar nerve can
often be made without exposing it.
ANÆSTHESIA OF FINGER.--The paraneural method applied to the digital
nerves at the root of the finger gives perfect results. A circle of
anæsthetic solution is first injected round the root of the finger.
The needle is then passed through the infiltrated skin on each side of
the finger, and a few drops of ½ per cent. novocaine solution injected
around the nerves. Complete anæsthesia of the finger results in a few
minutes.
IN THE LOWER LIMB injection of individual nerves is rarely employed,
as anæsthesia is easily obtained by the method of spinal analgesia.
The _lateral cutaneous_ can be injected as it lies immediately medial
to the anterior superior iliac spine emerging from under cover of the
inguinal ligament. This procedure may be useful in obtaining skin
grafts, the grafts being taken from the antero-lateral aspect of the
thigh. Amputations in the middle third of the thigh have been performed
by injecting the sciatic, the posterior cutaneous (small sciatic), the
femoral (anterior crural), and the lateral cutaneous at the root of the
limb. The obturator nerve is difficult to find and anæsthetise in such
cases. Operations below the knee can be painlessly performed by this
method of anæsthesia.
Operations on the Neck.
TRACHEOTOMY.--This operation is conveniently and safely performed under
infiltration anæsthesia. The anæsthetic solution is injected in the
usual way in the line of the incision down to the trachea but not into
it, as the trachea itself is insensitive to pain.
GOITRE.--A parenchymatous or adenomatous goitre can be readily
removed under local anæsthesia, though the administration of ether by
intra-tracheal insufflation is usually to be preferred. The principal
nerve supply to the field of operation is derived from the cervical
plexus, whose branches become superficial about the middle of the
posterior border of the sterno-mastoid. An intradermal injection may
be made first at this point, and a longer needle then passed down
to the posterior border of the muscle, and an area of infiltration
produced. From this point the needle is directed first upwards and
then downwards round the margin of the goitre so as to produce a zone
of infiltration. The same procedure may be repeated on the opposite
side, so that the whole gland is surrounded with a zone of infiltration
with a special depot of solution around the branches of the cervical
plexus. Where only one lobe is involved, it is sufficient to carry the
injection down in the middle line after one side has been encircled.
When the sheath has been incised and the surface of the gland exposed,
the isthmus is infiltrated and divided. The affected half of the gland
is then rolled outwards, and the attachments between the posterior
aspect of the gland and the larynx and trachea are infiltrated, special
attention being paid to the upper pole. The rest of the operation can
then be carried out painlessly.
EXOPHTHALMIC GOITRE may also be operated upon under local anæsthesia
after a preliminary hypodermic injection of morphia and scopolamin,
though many operators prefer a general anæsthetic on account of the
nervous state of the patient. In bad cases a procedure which is
often of great value is ligature of the superior thyroid artery on
both sides under local anæsthesia. After ligature of the vessels a
colloid degeneration takes place in the gland, and the symptoms of
hyperthyroidism subside. After a delay of two or three months it may
be possible to carry out the radical operation with little or no
danger. The incision is two and a half inches in length, and crosses
transversely the central part of the thyroid cartilage. The line of the
incision is infiltrated with novocain solution in the ordinary way, and
both superior thyroid arteries exposed and ligatured.
Operations on the Thorax.
The greater part of the wall of the thorax is supplied by the
intercostal nerves. In front the supraclavicular nerves come down
as far as the second intercostal space or sometimes as far as the
nipple, and the lateral and medial anterior thoracic nerves supply
the pectoral muscles, sending a few twigs to the overlying skin. The
long thoracic nerve extends down the side of the chest, supplying the
serratus anterior. The intercostal nerves can be blocked in the region
of the angles of the ribs and the supraclavicular by carrying a line of
infiltration along the clavicle. The anterior thoracic can be blocked
by deeper injections. In this way the greater part of the chest wall
and the pleura can be anæsthetised.
ACUTE EMPYEMA.--This operation should always be performed under local
anæsthesia. Exhaustion from septic absorption and from the antecedent
pneumonia or other disease, with the dyspnœa from the pressure of the
pus on the lung may render a general anæsthetic highly dangerous. The
method of producing local anæsthesia is simple and easily carried out.
A point is selected on the rib which is to be resected a short distance
behind the line of the incision and an intra-dermal injection made with
a fine needle. A long needle is then substituted and passed down to the
upper border of the rib until it reaches the plane between the external
and internal intercostal muscle, the injection being continued lightly
as it advances. When the desired point is reached one or two drams of
the solution are injected. The needle is then slightly withdrawn and
passed to the lower border of the rib to reach the same plane and the
same procedure carried out. The infiltration is then carried along
the line of the incision or it may be made to pass obliquely upwards
to the rib above and obliquely downwards to the rib below so as to
catch up the nerves coming from behind into the area of operation. The
anæsthesia of soft parts, bone, and pleura is perfect after the above
injection.
Operations on the Abdomen.
The anterior abdominal wall, including the anterior parietal
peritoneum, is supplied by the lower six intercostal nerves, the last
thoracic nerve, and the ilio-hypogastric and ilio-inguinal nerves
from the first lumbar. It is a very interesting and important fact
that, although the parietal peritoneum is exceedingly sensitive to
touch and pain, the visceral peritoneum and the viscera themselves
are insensitive. When operations are performed under local anæsthesia
of the abdominal wall, the viscera can be freely handled or incised
without the patient experiencing the slightest discomfort, provided
that the parietal peritoneum is not put upon the stretch by traction
on the mesentery or other peritoneal attachment. Thus the colon
can be opened twenty-four or forty-eight hours after being brought
outside the abdominal wall without any anæsthetic in the operation of
colostomy. Local anæsthesia is therefore well adapted to cases in which
a small amount of manipulation of the viscera is required, and where a
general anæsthetic would be dangerous, as in grave cases of intestinal
obstruction and in cases of carcinoma of the œsophagus with weakness
and loss of flesh from starvation.
GASTROSTOMY.--This operation is commonly performed under local
anæsthesia and may be taken as an illustration of the procedure
employed. The incision is made through the middle of the left rectus
and is about two and a half or three inches long, beginning about an
inch below the costal margin. An intradermal wheal is established at
the middle of the proposed incision. A long needle is entered at this
point and passed first upwards and then downwards in the line of the
incision, infiltrating the subcutaneous fat as it goes. The needle is
then passed in through the anterior wall of the rectus sheath, this
being easily recognised as a plane of decided resistance. The needle
is advanced a little inside the sheath, the injection being continued
as it advances. The same procedure is repeated at various points along
the line of the incision. The extra-peritoneal fat may be infiltrated
in the same way, the posterior wall of the sheath being identified
as a deeper plane of resistance and gently pierced. This step may be
deferred until the posterior wall of the sheath has been exposed.
The infiltration may be completed by forming a line of intradermal
infiltration along the line of incision, though this last step can
often be omitted.
The abdomen can then be opened painlessly. The only step in the
operation which may cause a little discomfort is the traction which may
be necessary to bring the shrunken stomach down from under cover of the
ribs. The incision into the stomach is quite painless.
GASTRO-ENTEROSTOMY can be performed under local anæsthesia, the only
special step required being infiltration of the meso-colon before it is
perforated.
APPENDICECTOMY is not suitable, as a rule, for local anæsthesia. If the
cæcum is fixed or the appendix bound down by adhesions, the traction
necessary to bring the appendix to the surface causes considerable pain.
In ACUTE OBSTRUCTION, when the procedure of enterostomy has been
decided upon owing to the gravity of the patient’s condition, local
anæsthesia is often of great value. The abdominal wall is infiltrated
in the manner described, and a distended loop of bowel brought to the
surface and sutured to the parietal peritoneum. A Paul’s tube can then
be introduced.
INGUINAL HERNIA. Local anæsthesia is specially suited to cases of
strangulated hernia, but it may be employed in the ordinary case. It
should be pointed out that spinal anæsthesia gives equally good results
and is less troublesome to carry out.
The injection is commenced with a fine needle a little beyond the
lateral end of the proposed incision. An intradermal wheal is produced
at this point, a long needle introduced into the subcutaneous tissue,
and about half-an-ounce of anæsthetic solution injected in this
position. The needle is then passed downwards and medially, and the
subcutaneous fat infiltrated in the line of the incision. The needle
is then partly withdrawn and again advanced until it reaches the
resistance of the aponeurosis of the external oblique. This is gently
pierced and about half-an-ounce of solution injected underneath so as
to block the ilio-hypogastric and ilio-inguinal nerves. In most cases
this is all that is necessary. As additional precautions the line of
incision may be infiltrated intradermally, and an injection may be made
around the neck of the sac after it is exposed.
FEMORAL HERNIA.--A femoral hernia may be anæsthetised by infiltration
along the line of the incision, or by injecting around the
circumference of the hernia after the method of Hackenbruch. After
the sac has been exposed and defined, it is necessary to inject some
novocaine solution around the neck, care being taken to avoid the
femoral vein which lies on the lateral side.
UMBILICAL HERNIA.--Local anæsthesia is sometimes of great value in
dealing with umbilical hernia, especially if it is strangulated, in
stout patients who are bad subjects for a general anæsthetic. The
injection is best made around the circumference of the hernia. Several
intradermal injections are made at points around the swelling, and
through these the long needle can be introduced and the deeper tissues
infiltrated. If the muscles are fairly well defined and can be felt,
they may be infiltrated at the commencement, but it may be advisable in
fat subjects to inject only the subcutaneous tissues to begin with, and
to delay the injection of the muscles and extra-peritoneal fat until
the sac has been opened and a protecting finger can be introduced to
guard the intestines. Omental adhesions can be divided without causing
pain. If the intestines are extensively adherent to the sac it is
better to infiltrate the points of adhesion, as extensive manipulation
may cause cramp-like pains.
After the circumferential injection has been made in these cases, it is
best to wait for ten or fifteen minutes before making the incision in
order to allow the anæsthetic solution to diffuse.
SUPRAPUBIC CYSTOTOMY.--In operations for drainage of the bladder local
anæsthesia is highly successful. The skin and subcutaneous tissues are
infiltrated in the line of the incision. The needle is then carried
between or through the recti muscles and several drams injected into
the layer of fat in front of the bladder. It is unnecessary to inject
the wall of the bladder itself.
HÆMORRHOIDS.--In patients in whom there is some contra-indication to
the use of a general anæsthetic the removal of hæmorrhoids can be
carried out quite safely and painlessly under local anæsthesia. A
circumferential injection is first carried out round the muco-cutaneous
junction. It is best to start the infiltration about an inch out
from the anus as the skin immediately around the anal orifice is
extremely sensitive. The infiltration is made subcutaneously, and each
re-insertion of the needle is made just short of where the previous
injection stopped. When the circumferential injection has been
completed, a finger is passed into the rectum, and the long needle
introduced through the anæsthetised area, injecting as it advances, to
a depth of about 2½ inches, keeping just outside the sphincters. Four
such injections are made, one on each side of the bowel, one in front
and one behind, from 5 to 10 c.c. being injected in each position.
Anæsthesia results almost immediately and the anal canal can be readily
dilated.
THE TONGUE.--For the Whitehead operation of removal of one half of the
tongue, complete anæsthesia can be obtained by the infiltration method.
A long needle is introduced at the tip of the tongue, and the injection
carried in the middle line to a point behind the tumour. The mucous
membrane of the floor of the mouth and the glosso-palatine fold are
infiltrated, and a last injection made across the affected half of the
tongue well behind the tumour.
The tongue can be anæsthetised also by blocking the lingual nerve
with a paraneural injection. The nerve lies under the mucous membrane
of the mouth opposite the last molar tooth. If the tongue is drawn
well over to the opposite side, the nerve can be felt and the
injection made around it. The only drawback to this method is that
it does not anæsthetise the posterior third, which is supplied by the
glosso-pharyngeal nerve.
OPERATIONS ON THE SKULL AND BRAIN can be readily performed by
infiltration of the scalp. In the later stages of the recent war, a
large proportion of operations on the skull and brain were performed
under local anæsthesia. The brain itself is insensitive to touch
and painful stimuli, and infiltration of the scalp is all that is
necessary. A 1 per cent. solution of novocaine with adrenalin has
been commonly employed, and is injected into the subaponeurotic space
so as to surround the field of operation with a wall of anæsthetic
solution--the method of Hackenbruch. The advantages are that hæmorrhage
is reduced to a minimum, and the head can be conveniently and safely
elevated and the intra-cranial tension thus reduced.
Analgesia from the Application of Cocaine to the Eye or to
a Mucous Surface.
FOR OPERATIONS ON THE EYE.--Analgesia is obtained by the instillation
of a few drops of a 4 per cent. solution into the conjunctival sac.
This is repeated two or three times, and analgesia is obtained in five
or ten minutes. It may be necessary to repeat the instillation during
the course of the operation.
FOR OPERATIONS ON THE NOSE, PHARYNX, OR LARYNX cocaine is commonly
used. A 5 or 10 per cent. solution is employed and is merely painted
on the surface. Care must be taken that such strong solutions are not
swallowed.
CHAPTER XXI.
SPINAL ANÆSTHESIA.
Spinal Anæsthesia or _Analgesia_, consists in the production of
analgesia in the lower extremities and in the lower part of the trunk
by the injection into the subarachnoid space of an anæsthetic drug
which blocks the spinal nerves as they enter and leave the spinal
cord. The cord ends at the lower border of the first lumbar vertebra
and the subarachnoid space at the second sacral vertebra so that there
is a considerable area into which the injection may be made without
risk of injury to the cord. It is, in reality, a special variety of
regional analgesia, the anæsthetic being injected into that part of
the subarachnoid space which is occupied by the cauda equina. The
subarachnoid space of the medulla spinalis contains the cerebro-spinal
fluid and communicates above with the subarachnoid space inside the
skull and through the foramen of Magendie, with the ventricular system
of the brain. The subdural space of the medulla spinalis is merely a
capillary interval. At the upper end of the cauda equina the nerve
trunks of the two sides are separated by a median interval--containing
only the filum terminale--which has been termed the cysterna
terminalis. It is into this median space that the injection is made, in
order to avoid wounding the nerve trunks and to procure equal diffusion
of the anæsthetic to both sides of the middle line. If the injection is
made among the nerve trunks on one side, a unilateral anæsthesia may
result, the drug being prevented from diffusing freely to the other
side by the presence of the numerous nerves.
The ligamentum denticulatum forms an imperfect scalloped septum between
the posterior and the anterior nerve roots, passing from the surface
of the cord to the dura mater. The presence of this septum probably
explains the fact that the motor nerves are not affected with the same
constancy and to the same extent as the sensory roots.
Technique.
The drug which is most commonly employed in the Edinburgh school is
Tropacocaine, and the results of its use with proper technique are
eminently satisfactory. The dose of the drug for most purposes is ·07
gramme. Smaller doses are sometimes used but the larger dose gives
more constant anæsthesia and appears to be well within the limits
of safety. The dose is dissolved in 1 c.cm. of distilled water and
sufficient sodium chloride added to make a solution isotonic with the
cerebro-spinal fluid. A convenient method of obtaining the drug is
in glass ampoules, each ampoule containing one dose, which has been
carefully sterilised.
[Illustration: FIG. 53.--Needle and syringe for
spinal analgesia. Note the short oblique character of the
point of the needle.]
The syringe and needle employed are illustrated in Fig. 53.
The point of the needle must be sharp but short. If a needle with a
long slender point is employed, only part of the point may enter the
membranes; a free flow of cerebro-spinal fluid may then take place,
but when the injection is made part of the anæsthetic solution escapes
outside the membranes. The needle should he 3½ to 4 inches long and 1
m.m. in diameter. A stylet fits inside the needle and prevents it from
becoming blocked during the introduction. To prevent the possibility
of rusting, both needle and stylet should consist of hard nickel. The
barrel of the syringe must consist of glass so that the appearance
of the cerebro-spinal fluid can be seen. The Record type is very
satisfactory. The syringe usually supplied for spinal analgesia has
a capacity of 2 or 3 c.cm., but one holding 10 c.cm. is more useful.
Syringe and needle must be carefully sterilised by boiling in plain
water; any trace of soda causes decomposition of the drug. The ampoule
containing the tropococaine is sterilised in a strong antiseptic
solution so as to avoid the possibility of contamination of the hands
when the drug is being transferred to the syringe.
_Method of Injection._--The patient should be given a hypodermic
injection of ⅛ gr. of morphine and ¹⁄₁₅₀ gr. of scopolamine an hour
before the operation. There are a number of minor variations in the
method of making the spinal injection, but limitations of space forbid
a discussion of theoretical questions and of the relative merits of
the different procedures. Only one method, which has been found safe
and reliable, will be considered here. The injection is made in the
space between the third and fourth lumbar spines, the objective being
the mid-line of the subarachnoid space between the two divisions of
the cauda equina. The position of the patient is such that the spaces
between the lumbar spines are opened up as widely as possible. The
most convenient plan is to have the patient sitting on the table with
the head and shoulders bent well forward (_see_ Fig. 54.) If the
patient is unable to sit up, the injection may be made with him lying
on his side, with the knees drawn up and the shoulders bent forward.
[Illustration:
FIG. 54. Position for the injection. The cross
indicates the point at which the lumbar puncture is
made--about half an inch from the median plane and in the
space between the third and fourth lumbar spines.]
The skin of the back is carefully sterilised; painting with tincture of
iodine serves admirably. The ampoule containing the tropacocaine is
opened, and the drug sucked into the syringe through a spare cannula.
The loaded syringe is then placed on a sterile towel at the back of the
patient. With a little practice there is no difficulty in making the
lumbar puncture. The fourth lumbar spine is located by noting the level
of the highest point on the iliac crest--this may be indicated by an
assistant. A line joining the highest points on the two iliac crests
will pass through the tip of the fourth lumbar spine. When this process
has been carefully identified, the needle is introduced half-an-inch to
one side of the median plane and midway between the third and fourth
spine. Some surgeons prefer to go in exactly in the middle line to make
sure of entering the middle of the subarachnoid space, but in this
position the tough supra-spinous and interspinous ligaments are met
with, and to avoid the resistance of these it is best to keep a short
distance out from the median plane. By carefully noting the direction
of the needle, the cysterna terminalis can always be entered. The
needle is passed forwards, very slightly upwards, and slightly medially
so as to hit off the centre of the subarachnoid space. As the needle
passes through the ligamentum flavum, there is a sudden diminution of
resistance and immediately afterwards the point of the needle lies in
the subarachnoid space. The passage of the needle through the membranes
is sometimes accompanied by a slight pricking pain.
The stylet is withdrawn at this stage and the cerebro-spinal fluid
usually trickles out drop by drop. The syringe is picked up, carefully
emptied of air bubbles, and fitted on to the needle. The piston is
withdrawn until the syringe is filled with cerebro-spinal fluid, which
mixes freely with the anæsthetic solution, and the contents then
slowly injected. The 10 c.cm. syringe is to be preferred for this
purpose as it is essential to mix the tropacocaine thoroughly with the
cerebro-spinal fluid. If the smaller syringe is used, it should be
refilled with cerebro-spinal fluid and emptied a second time so as to
ensure thorough diffusion of the drug. The needle is then withdrawn and
the puncture sealed with collodion.
The injection should never be made until a free flow of cerebro-spinal
fluid is obtained, since this is the only certain indication that the
needle has entered the subarachnoid space. If failure is met with in
the space between the third and fourth spines, the interspinous space
above or below should be tried.
After the injection has been completed the patient is placed flat on
his back and then lowered into the Trendelenburg position. Analgesia
appears first in the scrotum and perineum, extends down the medial
side of the leg to the foot, then appears on the front of the leg, and
travels up to the groin and the lower part of the abdomen. The progress
of the analgesia is tested from time to time by lightly pinching
or pricking the skin, the patient’s eyes being screened. When the
analgesia reaches the level of the nipples, the patient is raised into
the horizontal position and the the operation may be commenced. Some
surgeons object to the lowering of the head as rendering paralysis of
the respiratory centre from upward diffusion of the drug more likely.
If tropacocaine is used in the dosage indicated and the table elevated
when the anæsthesia reaches the nipple line, there seems to be little
risk of this complication. If analgesia is only desired in the lower
extremity, the lowering of the table may be omitted; but if a good
anæsthesia is desired above the level of the groin, it should always be
carried out.
Analgesia is complete in five or ten minutes as a rule. The duration
varies from three-quarters of an hour to an hour and a half. If a
preliminary hypodermic injection of morphine and scopolamine has been
given, the patient lies quietly and patiently until the operation is
completed. In some cases the patient actually drops off to sleep from
the effects of the morphine. It is not uncommon to observe a temporary
nausea and faintness about fifteen or twenty minutes after the
injection has been made, and it is good practice to give the patient a
little brandy and water at this stage.
Complications and After-Effects.
A great deal has been written in the past with regard to unpleasant
results of spinal analgesia, but most of these would appear to have
been the result of faulty technique or of the use of an impure or
irritating drug. When tropacocaine is used in the manner described, the
usual result is that, except for occasional nausea and faintness at
the commencement, the patient has a comfortable, painless operation,
and a recovery which is unmarred by the sickness and other distressing
symptoms which are so common after general anæsthesia.
_Deaths_ have been recorded, and these have been ascribed to
the drug having travelled too high and brought about paralysis of
the respiratory centre in the medulla oblongata. Too much importance
has probably been ascribed to these fatal cases. They have been most
common in patients greatly enfeebled by shock, old age, or debilitating
illness, who are liable to die during the operation whatever anæsthetic
is used. Thousands of cases have been recorded without a death, and
in the hands of surgeons of skill and judgment fatal cases are almost
unknown.
An occasional complication is severe _headache_ which may
persist for a week or longer. Other complications are all exceedingly
rare; paralysis of the lateral rectus muscle of the eyeball or of
other ocular muscles has been recorded, and is probably due to toxic
bye-products which are the result of impurity of the drug. Persistent
nausea and paralysis of the bladder and rectum and even of the lower
extremities have also been recorded, but are to be regarded as the
greatest rareties, and probably due to impurity of the anæsthetic.
Indications.
Spinal analgesia may be used for any operation at or below the level of
the umbilicus. Excellent anæsthesia is obtained for the operation for
radical cure of umbilical hernia, but anæsthesia above this level is
not so constant, and is regarded by many authorities as unsafe.
The procedure is of special value in cases in which a general
anæsthetic is unsafe:--(1) In old enfeebled patients suffering from
strangulated hernia, enlarged prostate, disease of the female pelvic
organs, and other conditions where anæsthesia is necessary below the
umbilicus. (2) In patients who are already suffering, or who are likely
to suffer, from severe shock. The drug has the same effect on the nerve
trunks of the cauda equina as on the peripheral nerves--it causes
blocking of the centripetal sensory impulses which are such a potent
factor in the causation of shock.
(3) In diabetic gangrene spinal analgesia is the safest form of
anæsthesia to employ.
Contra-Indications
Children up to the age of fourteen or so are apt to be frightened,
and spinal analgesia is better avoided except in special cases. It
is contra-indicated also in septic conditions on account of the
possibility of septic meningitis resulting from metastasis of the
infection, the drug having possibly the action of lowering the vitality
of the cord and meninges. In tuberculosis and syphilis it is better
avoided for the same reason. It should not be used where organic
disease of the spinal cord or brain is already present.
Analgesia Produced by Freezing.
A transient analgesia can be produced by freezing the skin. An ether
spray was formerly employed, but was found to be troublesome and
inconvenient. The most convenient procedure consists in freezing the
part by means of a spray of ethyl chloride. This drug is supplied in a
glass cylinder with a very fine outlet so that it breaks up into a fine
spray as it escapes. The cylinder is held about 8 or 10 inches from the
patient’s skin, and pressure applied with the thumb to a stopcock on
the neck of the cylinder. Under the influence of the heat of the hand
the liquid escapes in a fine jet which impinges on the patient’s skin.
Freezing takes place in a few seconds, the frozen patch becoming hard
and white. The freezing can be hastened by blowing on the skin.
This method is only suitable for the opening of small abscesses and
other procedures requiring a very short anæsthesia. The anæsthesia is
very imperfect, and only lasts for a few seconds. Many patients appear
to have as much pain with this form of anæsthesia as without it.
APPENDIX I.
SOME EXPERIMENTAL OBSERVATIONS BY THE AUTHOR UPON THE
PHYSICAL FACTS OF ETHER EVAPORATION.
The apparatus was very simple. It consisted of a pump which would
propel air towards the ether bottle; a glass bottle containing ether,
the roof of which was pierced by two tubes, one of which carried the
air from pump to bottle, and the other from bottle to a Waller’s tube,
where it was collected. The percentage of ether in the air was then
estimated by Waller’s gravimetric method. The ether jar stood in a
water bath which could be either left otherwise empty or filled up
with water of known temperature. The following tables show some of the
results. In each case, the air was propelled for five minutes, by which
time the cooling effect upon the ether was very marked; the figures
given are averages taken from several observations.
TABLE A.
AIR BLOWING OVER SURFACE OF ETHER.
+---------------------+----------------+----------+--------------+----------+
| Temperature of | Quantity of | Rate | Temperature | |
| Bath (Fahr.) | ether before | of | of ether |Percentage|
| before experiment. |experiment. | pump. |(Fahr.) at end|obtained. |
| | | |of experiment.| |
+---------------------+----------------+----------+--------------+----------+
| 75 | 100 c.c. | 30 | 50 F. | 12·7 |
| 85 | 100 c.c. | 30 | 52 F. | 12·8 |
| 75 | 100 c.c. | 90 | 45 F. | 8·7 |
| 85 | 100 c.c. | 90 | 45 F. | 8·8 |
| No water in bath | 100 c.c. | 30 | 32 F. | 8·2 |
| No water in bath | 100 c.c. | 90 | 23 F. | 5·4 |
| No water in bath | 200 c.c. | 30 | 38 F. | 9·6 |
| No water in bath | 200 c.c. | 90 | 29 F. | 6·6 |
+---------------------+----------------+----------+--------------+----------+
TABLE B.
Showing increased percentage obtained by “bubbling through” instead of
“blowing over” ether--
WATER BATH AT 75° FAHR.
Quantity of ether. Rate of pump.
100 c.c. 30
Air blown over surface of ether gave percentage of ether 12·8
Air bubbled _through_ ether 23·8
TABLE C.
Showing amounts of ether vaporised at varying pump rates. In each case,
the temperature of the water bath was 75, and the initial amount of
ether was 100 cc.--
Pump Amount of Ether
Rate. Vaporised.
30 30 c.c.
90 38 c.c.
These experiments justify one in drawing the following conclusions:--
1. The effect of a water bath has a marked effect in increasing
the strength of the vapour yielded, but small variations in the
temperature of the bath (as between 75 and 85 Fahr.) have but
little effect.
2. If ether is vaporising quickly, it cannot pick up heat from
the water bath as quickly as it is losing its own heat. Though
not shown in the tables, the actual loss of temperature on the
water bath was small--about 2 degrees Fahr. during the five
minutes experiment.
3. The more forcible the blast of air blown over or through
the ether, the less the percentage of ether yielded. Table C
shows that this loss of percentage is not compensated for by an
increase in the total amount vaporised.
Of course, these results only apply to the case of a strong current
of air. If the current of air were _very_ small, the ether could
pick up heat as fast as it parted with it, and within moderate degrees
a little increase of the air stream would increase the total amount of
ether vaporised without reducing the percentage strength.
These results are of some practical importance in connection with
so-called “vapour anæsthesia” as given for instance by Shipway’s
instrument (page 90), and in devising and using the ether chambers of
intratracheal apparatus.
APPENDIX II.
THE PERCENTAGE STRENGTH IN OPEN ETHER.
Hewitt and Syme (_Lancet_, 27th Jan. 1912) estimated the percentage
of ether obtainable from an open mask with varying materials and
quantities of the drug. The results are tabulated below:--
A.--A WHOLE MASK JUST MOIST.
Material stretched Number of Percentage
on mask. layers. obtained.
Gauze 4 11
8 11·4
12 11
Flannel 1 8·0
2 8·0
Lint 1 10·0
B.--WHOLE MASK WET.
Gauze 4 12
8 13·4
12 14·0
Flannel 1 8·0
2 8·0
Lint 1 8·0
By excessive douching the observers were able to obtain 17 per
cent.
In these results, air and ether vapour were drawn by a pump through
the material to imitate the inspiration, but no attempt seems to have
been made to imitate expiration. The effect upon the material used of
moisture condensed from the expired air is not taken into account
in these experiments. This is a serious hiatus in the argument,
particularly as regards lint. This material in actual use rapidly
becomes quite sodden, and ether will not vaporise from it properly.
In spite of this fault, these observations may probably be taken as
being reasonably accurate.
With them may be compared the figures of Karl Connell, who, working
with quite accurate methods, estimated the percentages of ether
necessary to induce and maintain anæsthesia:--
Period of Anæsthesia. Percentage.
First 5 minutes (_i.e._ induction) 18
Next 25 „ 14
Next 30 „ 12
Next 60 „ 12·8
“Bad” subjects on the average required an extra 4 per cent. during
first half hour, feeble patients required 2 per cent. less.
(_Journal_ of the American Medical Association, 22nd March 1913).
APPENDIX III.
THE ACTION OF ANÆSTHETICS UPON THE BLOOD.
_The Blood Gases in Anæsthesia._
Buckmaster and Gardner (_Journal of Physiology_, vol. xli., p. 246),
analysed the blood gases in various stages of chloroform anæsthesia,
and some of their results are shown below in tabular form. They show a
very definite reduction in the oxygen content of the blood. So far as
one gathers from the text of the paper, the animals were not subjected
to any considerable trauma during the progress of the anæsthesia, so
that the figures arrived at with regard to the CO_{2} content do not
bear upon the Acapnia question. If there was no trauma, there would be
no deep breathing, and a reduction of CO_{2} could not be expected.
+---------------------------+------------------+-------------------+---------------+
| |Average volume in |Average composition| |
| |c.c. per 100 c.c. | per cent. | Relation |
| | of blood | of gas | of |
| |------+-----+-----+-------------------|O_{2} to CO_{2}|
| |CO_{2}|O_{2}|Nitr.|CO_{2}| O_{2}|Nitr.| |
+---------------------------+------+-----+-----+------+------+-----+---------------+
|Normal cats. | 25·07|13·60| 1·00| 63·2| 34·28| 2·52| 1 to 1·84 |
| | | | | | | | |
|Reflexes just re-appearing | 29·02|11·49| 1·33| 65·06| 25·44| 2·87| 1 to 2·55 |
| | | | | | | | |
|Reflexes just disappearing | 29·57| 7·78| 2·15| 69·14| 18·17| 5·09| 1 to 3·8 |
| | | | | | | | |
|2nd Stage Anæsthesia | 36·00| 8·14| 1·49| 71·27| 16·12| 2·95| 1 to 4·32 |
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_Other Blood changes in Anæsthesia._
Hamburger and Ewing (_Journal_ of the American Medical Assoc. 1908)
examined the blood changes incidental to surgical anæsthesia. Their
results may be condensed as follows:--
_Nitrous Oxide._--Hæmoglobin is not permanently decreased and no anæmia
follows the administration. Hæmolysis is not increased. The coagulation
time of the blood is not always affected in the same direction. Usually
it is slightly increased.
_Ether._--The hæmoglobin is slightly reduced and anæmia persists for
seven to ten days. Hæmolysis is not however materially increased.
There is some evidence of blood inspissation. The coagulation time is
markedly increased.
_Chloroform._--The hæmoglobin is reduced and a distinct anæmia
produced. Hæmolysis is definitely increased. There is a slight increase
in the coagulation time.
INDEX.
A
Abdominal operations, ix, 7
local anæsthesia in, 187
Abdominal muscles, rigidity of, 19
Abnormalities of anæsthesia, minor, 38
major, 140
Acapnia, 10, 29, 39
Accidents of anæsthesia, 140
Acetonuria, 153
Acidosis, 153
Adenoids, 127, 166
in status lymphaticus, 148
Adrenalin, 175
danger of, with chloroform, 113, 166
Aedentulous patients, 23
After-effects of anæsthetics, _see_ Sequelae
Ages, dosage of morphia at various, 45
selection of anæsthetic at various, 164
Airshaft, natural, 96
Airway, natural, 15, 31, 114, 145
artificial, 23
Alcoholics, anæsthesia in, 2, 87, 103, 137, 165
Alkaloids, 12, 43, 88, 103
Aneurysm, 56
Anoci-association, 11
Anoxæmia, 15
Arm, management of in anæsthesia, 157
regional anæsthesia of, 181
Arteries, spouting of, x, 37
Arterio-sclerosis, 56, 167
Artificial respiration, 146
Asphyxia, 15
Athetosis, 38
Atropine, 43, 45, 112, 147
Auer and Meltzer, 96
B
Barth 3-way tap, 50
Bicarbonate of soda in acidosis, 156
Bladder, reflexes from, 39, 168
local anæsthesia in operations upon, 190
Blistering, by chloroform, 109
Blood, changes in, during anæsthesia, 207
spouting of, from cut arteries, x, 37
Blood-pressure, in natural sleep, 1
in shock, 6
in asphyxia, 17
in nitrous oxide, 46
in ether, 75
in chloroform, 110
in ethyl chloride, 122
clinical observation of, 37
Blowing respiration, 34, 89
Boothby, on ether percentages, 99
Boyle, Mr Leonard, 70
Brachial plexus, nerve blocking in, 181
Brain, _see_ Nervous System
local anæsthesia for operation upon, 191
Breath-holding, 34, 112, 114
Breathing, deep (_see_ Acapnia)
Bronchitis, 150
C
Carbon-dioxide, 10, 18, 206
Cardiac cyanosis, 37
Cardiac disease, 107
Cardiac failure (_see_ Syncope)
Castration, anæsthesia in, 169
C.E. mixture, 84, 134, 137
Cells, nerve, changes in, 5
Centripetal impulses, 6
Children, 45, 94, 125, 164
Chloretone, 93
Chloride of ethyl (_see_ Ethyl Chloride)
Chloroform, administration of, 113
decomposition of, 109
delayed poisoning by, 153
physiology of, 109
Choice of anæsthetics, 162
Circulation, observation of, x, 37
in shock, 10
in asphyxia, 17
in valved breathing, 29
in nitrous oxide, 46
in ether, 75
in chloroform, 110
in ethyl chloride, 122
in C.E. mixture, 131
failure of (_see_ Syncope)
Circumcision, anæsthesia in, 169
Clarke’s apparatus, 69
Clenching of Jaws, 15, 24
Clinical phenomena of asphyxia, 18
of normal anæsthesia, 33
Closed ether, 78
Closed method, features of, 29
Clover’s inhaler, 78, 138
Cocaine, 170
Collapse (_see_ Syncope)
Conduction of nerve impulses, 3
Connell, Karl, 90, 205
Conjunctival reflex, 31, 35
Convulsions, 17
Corneal reflex, 32, 35
Crile, Prof., 5, 9
Crowing respiration, 16, 169
night crowing, 148
Cyanosis, 18, 37, 53
Cylinders for nitrous oxide, 43
for oxygen, 64
D
Dangers of chloroform, Prof. L. Hill upon, 120
Death, causes of, 17, 110, 140, 144, 148
Decomposition of chloroform, 109
of ether, 74
Deep breathing, 10
Degrees of anæsthesia, 31
Dental anæsthesia, 54, 57, 128, 131, 163
Depth of anæsthesia, 36
Dextrose in acidosis, 156
Difficulties of anæsthesia, major, 140
minor, 38
Dilatation of pupils, 5, 17, 35, 53, 66, 125, 136, 141, 143
Disease, relation of anæsthesia to, 166
acute infectious, 168
Dislocations, anæsthesia in reduction of, 164
Dorsal position, 157
Dosimetric method for chloroform, 114
for ether, 90
Dott, Mr N., direct laryngoscope, 104
Douche method, 20
Dread (_see_ Fear)
Drop bottles; chloroform, 117
ether, 83
Drop method, 30, 83
Drugs for local and spinal anæsthesia, 170 to 174
E
Emphysema, 167
Empyæma, 167, 187
Enema, before operation, 42
Ether, 74, _et seq._
closed, 78
intratracheal, 96
open, 83
physiology of, 75
rectal, 93
warmed vapour, 90
Ether, respiratory sequelæ of, 150
Ether tremor, 38
Ethyl chloride, 122, _et seq._
combined with nitrous oxide, 128
freezing anæsthesia by, 200
Eucain, 174
Excitement (_see_ Struggling)
Extraction of teeth (_see_ Dental Anæsthesia)
Eye reflexes, definition of, 31
F
Face-down posture, 157
Face, adaptation of masks to, 21, 52, 84
Face-pieces for nitrous oxide, 51
False anæsthesia, 41
Faradism of motor nerves in anæsthesia, 3
Fat patients, 158, 165
Fatty changes after anæsthesia, 153
Fear, effects of, 9
prevention of, 11, 43, 88
Feeble patients, 168
Ferguson, Dr., W. J., 87
Fingers, regional anæsthesia for, 184
Flame, open, dangers of, 74, 104
Forceps, tongue, 24
Food before anæsthesia, 42
Foreign bodies in the larynx, 16
Freezing analgesia, 201
Fright (_see_ Fear)
G
Gags, 25
Gardner, Mr Bellamy, 23, 24, 83
Gas and air, 54
Gas and ether, 138
Gas and ethyl chloride, 128
Gas-oxygen, 60
Gasping, 40
Genito-urinary operations, 168
Glossotilt, 24
Glottis, spasm of, 16, 20, 26, 105
Goitre, anæsthesia for, 160, 185
Goitre, exopthalmic, 9, 167
Grey and Parsons on shock, 6
Guy, Dr Wm., 128
Guy-Ross, gas oxygen method, 131
Gwathmey, warmed ether vapour, 90
oil-ether, 93
H
Hæmorrhage, as a factor in shock production, 9
observation of, by anæsthetist, x, 37
Hæmorrhoids, local anæsthesia for, 191
Harcourt, Vernon, 114
Head and neck operations, position for, 158
Head and neck, raising, 152
lowering, 110, 145
extra pillow in deep chested patients, 157
Heart, failure in asphyxia, 17
observation of, 37
action of ether upon, 75
of chloroform upon, 110
of ethyl chloride upon, 122
failure of, in secondary syncope, 144
Heart disease, anæsthetics in, 167
Henderson, Yandell, 10, 29
Hernia, local anæsthesia in, 189
Heroin, 44
Hewitt, Sir Frederick, 22, 50, 62, 81, 137
Hill’s direct laryngoscope, 104
Hill, Prof. Leonard, 111, 120
Hornabrook, 87, 123
Hydrochloric acid, as an impurity in chloroform, 109
Hypnotics, 12, 42
Hypodermic medication, 12, 42
I
Impurities of anæsthetics, 74, 109, 122
Infiltration analgesia, 175
Inhalers, Clover, 78
Clarke, 68
Guy, 128
Guy-Ross, 130
Hewitt, 50, 62, 81
Junker’s, 115
Ormsby, 81
Paterson, 58
Rendle, 135
Inhibition, vagal, 111, 143
Intestinal obstruction, 141, 189
Intranasal surgery, 160, 166, 192
Intratracheal method, 96
Kelly’s instrument for, 100
Shipway’s, 101
Inversion, Leonard Hill’s experiments upon, 110, 111
J
Jactitations, 53
Jaundice, 154
Jaws, clenching of, 15, 26
falling back of, 16
operations upon, 166
management of, in anæsthesia, 23, 85
Joints, anæsthesia in dislocation of, 164
Junker’s inhaler, 115
K
Kidney, position for operations upon, 168
Kelly’s intratracheal instrument, 100
L
Labour, anæsthesia in, 44, 169
Lane, Sir Arbuthnott, 14
Laryngeal stridor, 16, 20, 26, 40, 169
Levy, Goodman, 112, 145
Light anæsthesia, dangers of, in chloroform, 9, 112
Levy’s views, 113
Light reflex, 32
Local anæsthesia, 170 _et seq._
Lowering of head and shoulders, 110, 145
Lumbar puncture, site for, 196
Lungs, ventilation of, by normal breathing, 96
by intratracheal method, 97
Lymphatism, 148
M
Malcolm, J. D., 9
Marshall, Dr Geoffrey, 70
Masks for chloroform, 110
for ether, 82
for perhalation method, 28
Massage of heart, 148
Mechanical asphyxia, 15
Meltzer and Auer, on intratracheal method, 96
Menstruation, 169
Micturition before nitrous oxide, 51
Mixtures, C. E., 84, 134, 137
of nitrous oxide and oxygen, 60
of nitrous oxide and ethyl chloride, 128
Morphine, 12, 43, 152
Mouth, breathing through, 22
Mouth, operations upon, 165
Mouth props, 22
Mucus in air passages, 40
Musculo-spiral paralysis, 157
Muscles in anæsthesia, ix, 3, 19, 34
Muscle tone, 3, 19, 53
N
Nasal breathing, 23, 166
Naso-pharyngeal catarrh, 151
Nasal methods of giving nitrous oxide, 57
Nasal tube for Junker’s bottle, 119
Neck, position of, 20
relaxation of muscles of, 21
posture for operation upon, 159
tumours and inflammatory swellings in, 7, 166
Nephritis, influence of, upon choice of anæsthetics, 77, 168
Nervous system, effects of anæsthetics upon, 2, 75
Nerves, peripheral, unaffected by anæsthetics, 3
Nerve blocking, 12, 179
Night-crowing, 148
Nitrous oxide, 46
with air, 54
with ether, 138
with ethyl chloride, 128
nasal, 57
physiology of, 46
contra-indications to, 56
Nitrous oxide and oxygen, 8, 12, 60
various systems for, 67, 70, 130
for use in major surgery, 72
with ethyl chloride, 131
O
Obesity, 158, 165
Obstruction, intestinal, 141
respiratory, 15, 141
Oil ether, Gwathmey’s method of, 93
Oligæmia in shock, 10
Omnopon, 44
Open method, definition of, 28
chloroform, 117
ether, 83
ethyl chloride, 123
O’Malley’s technique for intra-nasal surgery, 160
Ormsby’s inhaler, 81, 137
Over-dosage, 36, 110, 144
with nitrous oxide, 54
Oxygen, reduction in blood in anæsthesia, 206
as a relief in asphyxia, 27
to old patients, 165
with nitrous oxide (_see_ Nitrous Oxide and Oxygen)
with nitrous oxide and ethyl chloride, 130
P
Paralysis, musculo-spiral, 157
Patella reflex in anæsthesia, 3
Percentages of chloroform and ether required in anæsthesia, 6
of chloroform, 111
of ether, 86, 99, 201, 204
Perhalation method, definition of, 28
ether (_see_ open Ether)
Phenomena of anæsthesia
normal, 33
abnormal, 38
of nitrous oxide, 52
of ethyl chloride, 125
Pericarditis as a cause of death in anæsthesia, 168
Phillip’s artificial airway, 23, 160
Physics of natural respiration, 96
Physiology of anæsthetic drugs, 1
of asphyxia, 17
of chloroform, 109
of ether, 75
of ethyl chloride, 122
of nitrous oxide, 46
Phthisis, 167
Pneumonia, post anæsthetic, 157
Position in anæsthesia, 157
Positive pressure in nitrous oxide, 52
in nitrous oxide and oxygen, 66
Post-chloroform poisoning, 153
Post anæsthetic complications, 150
Pregnancy, anæsthesia in, 169
Preliminary hypodermic medication, 11, 43, 152
Preparation of patient, 42
Primary syncope, 110, 143
Protection from shock by general anæsthetics, 8
Pulse, rate in shock, 6
clinical observation of, 37
Pupil, light reflex of, 32
size of, 35
in asphyxia, 17
Purging before anæsthetics, 40
Q
Quinine and urea hydrochloride, 174
R
Rebreathing method, 18
in nitrous oxide, 68
Rectal administration of ether, 93
Rectal saline, 42
Reflexes as a cause of shock, 4, 6
order of disappearance of, 3
Reflex, conjunctival, 31, 35
corneal, 32, 35
light, 32, 35
patella, 3
skin, 37
Reflex syncope, 8, 112, 145
Regional anæsthesia, 179
Renal disease, 163
Rendle’s cone, 135
Repeated administrations, 60, 156
Respiration, arrest of, 142
artificial, 146
blowing, 34, 89
crowing, 16
depressed, 39, 43
effect of morphia and chloroform upon, 43, 86
normal, 34
obstructed, 15, 141, 166
Respiration, physics of natural, 96
reflex arrest of, 39
Respiratory abnormalities, minor, 39
major, 141
Respiratory system, effects of ether upon, 76
after-effects of anæsthetics upon, 150
Rigidity of muscles in asphyxia, 19, 38, 39
in second stage, 33
S
Saline injections, per rectus, 42
subcutaneous, 14
Schimmelbusch’s mask, 28, 116
Scopolamine, 44, 103
Secondary syncope, 17, 138, 143
Secretion of mucus, 40, 76
of urine, 168
Sedatives, 12, 42
Selection of anæsthetic, 162
Semi-open method, 28
Septic cases, 9, 60, 156, 168
Sequelæ of anæsthesia, 100
Sex, relation to anæsthesia, 165
Shipway, Dr, 91, 101
Shock, 5
difference between syncope and, 142
Short, Mr Rendle, 154
Sickness (_see_ Vomiting)
Sighing, 40
Sight-feed machines for gas-oxygen, 70
Signs of anæsthesia, 36, 53, 65
Silk, Dr J. W., 23, 87
Single dose anæsthetics, 30, 163
Sitting posture, 21, 158
Slow respiration, 39
Spasm, muscular, 19
of jaw muscles, 15
of larynx, 16, 26, 169
Specific gravity of chloroform, 109
of ether, 74
Spinal anæsthesia, 193
Stages of anæsthesia, 31
Starvation, a cause of shock, 9
of acidosis, 155
Status lymphaticus, 148
Stertor, 40, 53
Stimuli from field of operations, 6
Stomach tube, before operation, 141
Stovaine, 173
Stridor, 16, 26, 40
Struggling, 34
Strychnine, 147
Subcutaneous saline, 14
Swallowing, movements of, 33
Sylvester’s method of artificial respiration, 146
Syncope, 142
Syringe for local anæsthesia, 176
for spinal anæsthesia, 176
T
Teeth, danger of dropping of into larynx, 16
extraction of, 54, 57, 128, 131, 163
Teter, Dr., on nitrous oxide and oxygen, 68
Thomson, Prof. Alexis, 12, 158
Thomson, Torrance, on intratracheal anæsthesia, 96
Thoracic operations, local anæsthesia in, 186
Three-way tap for nitrous oxide, 50, 128
Thyroid gland, _see_ Goitre
Time for operations, 42
Time afforded by single dose anæsthetics, 163
Tongue falling back of, 16
forceps for, 24
operations upon, 97, 118, 166
local anæsthesia for, 191
Tonsils and adenoids, 127, 166
Trachea, mucus in, 40
pressure upon, 17
Trachetomy, 142, 185
Tremor, ether, 38
Trendelenberg posture, 158
Tropacocaine, 173
Turner, Dr Logan, 125
U
Urine, secretion of prevented by morphia, 168
V
Vagus nerve, 110, 145
Valved method, features of, 29
Vapour method, ether, 90
ethyl chloride, 125
Vaso-motor system, in shock, 9
in asphyxia, 17
in nitrous oxide, 46 (and _see_ Physiology)
Veins, large, emptying into heart, 10
engorgement of, 20, 151
Venesection in syncope, 147
Veronal, 12
Vicious circle of asphyxia, 20
Vital medullary centres, 3
Vomiting, 140, 152
impending, 39, 141
W
War, anti-shock, measures in, 11
lessons of, 61, 151
Warming anæsthetic vapours, 62, 90, 101
Wedge for opening clenched jaws, 25
Withdrawal of anæsthetic, for stridor, 26
for breath holding and struggling, 34
for syncope, 145
FOOTNOTES:
[1] This can be done to a very limited extent indeed if the ordinary
valves here described are used. _See_ page 68.
[2] A safeguard provided on some machines is a side lead from the
oxygen supply direct to the facepiece whereby pure oxygen can be given
if required.
[3] The amount of oxygen in a cylinder is designated in terms of cubic
feet. A cylinder which would hold 100 gallons of N_{2}O, will contain
30 cubic feet of oxygen.
[4] In the figure the Clover is shown with gas valves and 2-gallon bag,
arranged for “gas and ether.”
[5] Trans. xvii. Internat. Med. Cong. Sub-sect. (vii.) Part i.
[6] _Journal_ Amer. Med. Assoc., Sept. 1913.
[7] Trans. xvii., Internat. Med. Cong. Sub-sec. (vii.), Part i.
[8] Trans. xvii., Internat. Med. Cong., Sub-sec. (vii.), Part ii.
[9] Trans. xvii., Internat. Med. Cong., Sub-sec. (vii.), Part I.
[10] The student should be careful to be sure that the bulb is attached
to the _inlet pipe_: if by accident it be slipped on to the outlet
pipe, the first compression of the bulb will eject a stream of liquid
chloroform from the instrument.
[11] The author described this method in a paper read before the
Scottish Branch of the British Dental Association, and afterwards
published in the _Journal_ of the Association under the title “The
Edinburgh System of Dental Anæsthesia.” To the use of this term Dr J.
H. Gibbs, of Edinburgh, took strong exception in a letter to the Editor
of the _Journal_. The author has and had no desire to convey the
impression that this system was universally used in Edinburgh, but
simply that it is the method taught by Dr Guy, Dean of the School, to
the students in the Extraction Room.
Transcriber’s Notes:
1. Obvious printers’, punctuation and spelling errors have been
corrected silently.
2. Where hyphenation is in doubt, it has been retained as in the
original.
3. Some hyphenated and non-hyphenated versions of the same words have
been retained as in the original.
4. Superscripts are represented using the caret character, e.g. D^r. or
X^{xx}.
5. Italics are shown as _xxx_.
6. Bold print is shown as =xxx=.
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