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.