of chloroform, and the temperature of the vapour and air which the
patient breathes are generally reduced a good deal, but not to the same
extent as during the inhalation of ether. In giving chloroform from a
small sponge which had been squeezed out of water, I have sometimes
observed, after laying it down, that it became covered with a kind of
hoar frost; the minute particles of frozen water having a slight taste
of chloroform. The cold produced by the evaporation of a liquid like
chloroform is often the means of checking the evaporation to a certain
extent, and limiting the amount of vapour which is taken up by the air.
PHYSIOLOGICAL EFFECTS OF CHLOROFORM.
Chloroform belongs to the large class of medicines known as
narcotico-irritants. This and some other agents which have been inhaled
for the prevention of pain are often called anæsthetics; a name to which
there is no objection, so long as it does not lead to the idea that they
have a different action from other narcotics, or more precisely
speaking, narcotico-irritants; there being no such medicines as pure
narcotics. The term anæsthesia has been frequently employed to designate
the insensibility and suspension of consciousness caused by chloroform
and ether; but, in describing the effects of these agents, I shall
confine this term to its original meaning, privation of feeling, and I
shall employ the term narcotism to designate the entire effects of these
agents on the nervous system. This is the sense in which the term
narcotism has always been employed. It has been the custom, however, to
restrict the use of the word very much to cases in which stupor existed,
but I shall apply it to designate the slighter, as well as the more
profound effects of a narcotic, as I am entitled to do by strict
etymology.
In order to facilitate the description of the effects of chloroform, I
have been in the habit of dividing them into degrees. I use the term
degree in preference to stage, as, in administering chloroform, the
slighter degrees of narcotism occur in the later stages of the process,
during the recovery of the patient, as well as in the beginning. The
division into degrees is made according to symptoms, which, I believe,
depend entirely on the state of the nervous centres, and not according
to the amount of anæsthesia, which there is good reason to conclude,
depends, in a great measure, on the local action of the chloroform on
the nerves. The different degrees of narcotism glide insensibly into
each other.
In the first degree, I include all the effects of chloroform that exist
while the patient retains a perfect consciousness of where he is, and
what is occurring around him. This degree constitutes all that a person
remembers of the effects of the vapour, except when he happens to dream,
and recollect it afterwards. The sensations caused by inhaling
chloroform are usually agreeable, when it is taken merely for curiosity;
and individuals who have inhaled nitrous oxide at some previous time of
their lives, often describe their feelings as being very much the same
from both agents. Patients who are about to undergo a surgical operation
are, however, not always in a state for receiving agreeable impressions,
and they sometimes complain of palpitation of the heart, and a feeling
of fulness in the head. There is generally a sense of dizziness, with
singing in the ears and tingling in the limbs. Many persons have a
feeling like that of rapid travelling, and as an appearance of darkness
sometimes comes on from the failure of the sight, whilst there is also a
loud noise in the ears, it not unfrequently happens that a person feels
as if he were entering a railway tunnel, just when he is becoming
unconscious.
Those persons whose mental faculties are most cultivated appear usually
to retain their consciousness longest whilst inhaling chloroform; and,
on the other hand, certain navigators and other labourers, whom one
occasionally meets with in the hospital, having the smallest possible
amount of intelligence, often lose their consciousness, and get into a
riotous drunken condition, almost as soon as they have begun to inhale.
There is a widely different class of persons who also yield up their
consciousness very readily, and get very soon into a dreaming condition
when inhaling chloroform. I allude to hysterical females.
There is often a considerable diminution of the common sensibility
during the first degree of narcotism by chloroform, more especially when
it is inhaled very slowly, so that the patient is kept some minutes
partially under its influence. In this way neuralgia can often be
relieved, without removing the consciousness, when it is not extremely
severe, and the suffering of labour may often be removed in the same
manner, when the pains are not very sharp. In a few cases, the
extraction of a tooth and other minor operations have been performed
without pain, whilst consciousness has been retained; but as a general
rule, it is better not to operate under these circumstances, for failure
is more likely than success; and this plan does not succeed in any case
without inhaling longer, and consuming more chloroform, than would be
necessary in the usual way. The complete recovery of the patient from
the effects of the vapour, after a protracted inhalation of this kind,
is also more tardy.
The first degree of narcotism recurs when consciousness returns as the
effect of the chloroform is subsiding. At this time, there is generally
a greater amount of anæsthesia than at the commencement of inhalation,
just before consciousness is removed. I have many times known the
introduction of sutures, and such like measures, performed at the
concluding part of an operation, after the patient had recovered his
consciousness, without his feeling what was being done. As a general
rule also, the smarting of the wound does not commence till some time
after consciousness has returned.
In the second degree of narcotism, there is no longer correct
consciousness. The mental functions are impaired, but not necessarily
suspended. When a patient inhales chloroform quietly for a medical or
surgical purpose, he usually appears as if asleep in this degree; but if
his eyelid be raised, he will move his eyes in a voluntary manner. There
are occasionally voluntary movements of the limbs; and although the
patient is generally silent, he may nevertheless laugh, talk, or sing.
Persons sometimes remember what occurs whilst they are in this state,
but generally they do not. Any dreams that the patient has, occur whilst
he is in this degree, or just going into, or emerging from it, as I have
satisfied myself by comparing the expressions of patients with what they
have related afterwards. There is sometimes a little trouble with the
patient in this degree of narcotism. He feels the inconvenience of the
vapour he is breathing, and having become unconscious of the object for
which it is inhaled, he endeavours to push away the inhaler. As a person
in this condition can generally hear and partly understand what is said,
a few kind words will often render him tractable. This is generally true
of all those who have been brought up with care and kindness, more
especially patients of the female sex; but the man who has been roughly
treated from the time of his birth, can often be made insensible only by
means of a little restraint.
There is generally a considerable amount of anæsthesia connected with
this degree of narcotism, and I believe that it is scarcely ever
necessary to proceed beyond it in obstetric practice, not even in
artificial delivery, unless for the purpose of arresting powerful
uterine action, in order to facilitate turning the fœtus. The loss of
sensation is indeed sometimes so complete in this degree, especially in
children, that the surgeon’s knife may be used without pain; I have
indeed seen a child unconsciously handling its toys all the time that
the operation of lithotomy was performed on it. Commonly, however, the
use of the knife, when the narcotism has not proceeded further than this
degree, occasions expressions indicative of pain, which are either not
remembered, or are recollected as having occurred in a dream. The
patient is generally in this degree during the greater part of the time
occupied in protracted operations; for although, in most cases, it is
necessary to induce a further amount of narcotism before the operation
is commenced, it is not usually necessary to maintain it at a point
beyond this.
In the third degree of narcotism, there are no longer any voluntary
motions. The eyes, for instance, are not directed towards any object;
and although the limbs may move, they are not directed to any purpose.
The pupils are generally inclined upwards in this degree, and are at the
same time usually somewhat contracted. The bloodvessels of the
conjunctiva are generally somewhat enlarged in this degree in all
persons who are well nourished and not deficient in blood. It is in this
degree of narcotism that rigidity and spasms of the muscles occur in
certain cases. These phenomena occur most frequently in cases where the
muscles have been much exercised, and are consequently well nourished.
They are never met with in infancy, and rarely before puberty. They are
much more common in the male than the female sex. The rigidity and spasm
are greatest and most constant in labourers and persons accustomed to
athletic exercises, and they are usually absent in patients who have
been long confined to the room, or are much reduced in strength from any
cause. They are less marked in old age than in the middle period of
life, and they are not by any means so frequent or strong in fat, as in
thin, muscular persons. I have seen the spasms take an epileptiform
character in a few cases; but by gently continuing the chloroform, they
have always been subdued. In a great number of cases, the patient
mutters in an almost inarticulate and a perfectly unintelligible manner,
just as the muscular rigidity and spasm are subdued. Under these
circumstances, I have never heard a single word pronounced so that it
could be understood. If articulate language is uttered just after the
muscular rigidity, it is evidence that the effects of the chloroform are
being allowed to diminish, and that the patient is going back into the
second degree of narcotism.
In the third degree of narcotism, a person is quite incapable of having
any perception or consciousness of pain, but anæsthesia is not a
necessary part of this amount of narcotism when it is first induced, and
in some cases a patient may flinch, and put on an expression of
countenance which seems indicative of pain. He may also cry out, but not
in an articulate manner. By continuing the chloroform gently for a
minute or so, a state of complete anæsthesia can be induced in nearly
every case, without carrying the narcotism of the nervous centres
further than this degree. The loss of sensibility of the conjunctiva, as
shown by the absence of winking when the edges of the eyelids are gently
touched, is the best criterion that the patient will bear the knife
without flinching or crying.
The circumstance of the anæsthesia, or loss of common sensibility, not
keeping pace with the degree of narcotism of the brain, as shown by the
presence or absence of consciousness and volition, appears to depend on
the chloroform acting on the peripheral distribution of the nerves, as
well as on the nervous centres.[49] The following considerations support
this view. 1. Chloroform has the effect of diminishing the sensibility
of a part to which it is applied locally, even to the sound cuticle.
When the cuticle is removed, the local anæsthesia of the surface is
complete; and in frogs, which have a thin permeable skin, and a languid
circulation, one limb can be rendered insensible, by the local
application of this agent, before the remainder of the animal is much
affected. 2. Chloroform when inhaled immediately circulates throughout
the body, in all parts of which it can be detected by chemical means. 3.
Chloroform and other narcotics suspend the function of the nerves, when
locally applied to them. 4. When inhaled, the local effect of chloroform
must be greatest when it has had time to exude through the coats of the
vessels, into the extra vascular liquor sanguinis, and come into
immediate contact with the nervous fibrillæ; and it must take some
little time after the chief part of the chloroform has escaped from the
blood during its passage through the lungs, before that which is in the
lymph external to the vessels can pass back again into them, by
endosmosis. The brain, on the other hand, is without lymph and
lymphatics. The blood in this organ is all contained within the vessels,
in which, moreover, it circulates with more velocity than in the
external parts of the body. It can be easily understood, therefore, how
the brain may escape from the effects of the vapour whilst the nerves of
sensation throughout the body still remain partially under its
influence. 5. It is in young subjects, in whom, connected with the more
active process of nutrition, the quantity of lymph external to the
vessels is greatest, that the general insensibility most frequently
remains, whilst the cerebral hemispheres are resuming their functions;
whilst in persons of spare habit, approaching the middle or later
periods of life, there is little anæsthesia except in the unconscious
state.
The co-operation of the brain with the nerves is, of course, necessary
to sensation; and it is possible by a large dose of chloroform to
produce complete anæsthesia very suddenly, before there is time for the
nerves to be acted on locally to any extent; and if the chloroform is
not continued, the anæsthesia may subside as quickly as it was induced.
The large ganglia of sensation, the optic thalami, seem to require a
greater quantity of chloroform to suspend their function than is
necessary to suspend that of the cerebral hemispheres, but, by occupying
three or four minutes in giving chloroform, one is enabled to add its
local action on the nerves to its influence on the brain, and thus to
induce anæsthesia with less narcotism of the nervous centres than would
otherwise be required.
It must not be supposed that the difference of the action of chloroform
on the cerebral hemispheres, and on the optic thalami, will of itself
explain the want of uniformity between the loss of consciousness and
loss of feeling. If it were a mere difference of degree, it might be so
explained; but the absence of all regular relation between these
phenomena can only be satisfactorily accounted for when the
circumstances connected with the circulation and the liquor sanguinis,
that I have endeavoured to explain above, are taken into account.
In the fourth degree of narcotism, the breathing is stertorous, the
pupils are dilated, and the muscles completely relaxed. The patient is
always perfectly insensible. It is very seldom necessary to carry the
effects of chloroform as far as this degree. It is, however, sometimes
requisite to do so, in attempting to reduce dislocations of long
standing in muscular persons, and whilst the surgeon is dissecting in
the neighbourhood of important vessels and nerves, in certain robust
subjects and others who seem to have acquired an excess of sensibility
by hard drinking, and who can hardly be kept quiet under the knife,
except when the breathing is stertorous.
There are some further effects of chloroform with which one becomes
acquainted in experiments on the lower animals. If the inhalation is
continued after the symptoms just described are produced, the breathing
is rendered difficult, feeble, or irregular, and is sometimes performed
only by the diaphragm, whilst the intercostal muscles are paralysed. If
the dose of chloroform is gradually increased after these effects are
produced, the breathing entirely ceases, but the heart continues to
pulsate very distinctly, till its action becomes arrested by the absence
of respiration, as in asphyxia. This interval, including the
embarrassment and cessation of the breathing, I call the fifth degree of
narcotism.
Although the respiration may be suspended by an amount of chloroform
that has very little direct effect in the motion of the heart, it is
quite possible to stop the heart’s action by the immediate effect of
this agent. When frogs are exposed to the action of the vapour, they go
on absorbing it by the skin, after the respiratory movements have
ceased; and in this way the pulsations of the heart are arrested, when a
certain amount of chloroform has been absorbed into the blood. And when
animals of warm blood are made to breathe air containing as much as
eight or ten per cent. of the vapour of chloroform, the blood which is
passing through the lungs becomes so charged with it as to stop the
action of the heart, when it reaches that organ through the coronary
arteries. It is in this way that accidents from chloroform have
happened. The power of this agent to arrest the pulsations of the heart
can also be shewn, by blowing a stream of the vapour on its surface,
when the chest is opened immediately after the breathing has ceased, and
whilst it is still beating.
The ultimate and greatest effect that chloroform is capable of producing
on the animal body is to destroy the irritability of the muscles, and
produce the post-mortem rigidity. Either the whole body or a single limb
can be rendered instantly rigid by injecting the arteries with a little
chloroform shaken up with water. The rigidity remains for weeks in the
dead body, and would probably be permanent if the chloroform were
prevented from evaporating. Whilst it lasts, putrefaction is of course
prevented.
_Effect of Chloroform on the Pulse._ I have not mentioned the state of
the pulse in the above description of the effects of chloroform, for it
affords no criterion of the amount of narcotism, and it was better
therefore to reserve it for a separate notice. It is nearly always
increased both in force and frequency, more especially at the early part
of the inhalation. After the patient has become quite insensible, the
pulse indeed generally settles down nearly to the natural standard, and
in the middle of the most formidable operations, it is often beating
with natural volume and force, not more than sixty or seventy times a
minute. The pulse rarely becomes weaker or slower than natural under the
influence of chloroform, except from considerable loss of blood, or
where the patient is about to be sick. I have twice found the pulse as
slow as 44 in the minute at the conclusion of an operation attended with
great loss of blood. One of the cases was the removal of a large tumour
of the labium pudendi, in a woman, aged forty-five, on the 28th of
April, 1849, at King’s College Hospital, by Mr. Fergusson. The pulse
was, however, not small or weak, and there was no faintness. In a few
minutes, the patient vomited, and the pulse immediately resumed its
natural frequency.[50]
There is occasionally a feeble state of pulse with a feeling of
faintness as the effects of the chloroform subside, and in two or three
cases in which the patient was in a sitting posture, positive syncope
occurred, which, however, was promptly removed by the horizontal
position. The persons most liable to a feeling of faintness after
chloroform, are those who are subject to syncope from slight causes.
_Action of Chloroform on the Nervous System._ Chloroform, when inhaled,
immediately reaches every part of the nervous system through the
circulation, and it acts on every part of that system from the first, as
a careful observation of the symptoms proves. It does not, however, act
equally on all parts of the nervous system, according to the quantity
which is absorbed; some parts of that system have their functions
entirely, or almost, suspended, whilst others are but little under the
influence of the vapour, and it is owing to this fact that the most
severe pain may be prevented without danger. M. Flourens made the
following remarks respecting the action of sulphuric ether, and they
apply equally well to the effects of chloroform, when it is inhaled
gradually: “Under the action of ether, the nervous centres lose their
powers in regular succession—first, the cerebral lobes lose theirs,
viz., the intellect; next, the cerebellum loses its, viz., the power of
regulating locomotion; thirdly, the spinal marrow loses the principle of
sensitiveness and of motion; the medulla oblongata still retains its
functions, and the animal continues to live: with loss of power in the
medulla oblongata, life is lost.”[51] I may add, that after the
breathing has ceased, from the loss of power of the medulla oblongata,
the ganglionic nerves still perform their functions, and the heart and
intestines continue to move for a time, often with vigour.
Owing to the unequal effects of a given quantity of chloroform on
different parts of the nervous centres, and owing to its acting also on
the nerves, a variety of states may be met with during a surgical
operation, some of which have often been thought curious, or anomalous.
The most usual state of the patient during an operation, when chloroform
is successfully administered, is one of perfect quietude, without any
sign of consciousness or sensation. The patient under chloroform may,
however, moan, or cry, or flinch, or show other symptoms which are
usually thought indicative of pain, but without using any articulate
language, or remembering anything of the operation afterwards. If his
flinching or crying out has neither interfered with the surgeon, nor
distressed the friends who may be present, a case of this kind may be
considered satisfactory. A third condition of the patient under the
influence of chloroform is that in which he talks, or laughs, or sings
during the operation, his words having no reference to what is being
done. If he is sufficiently quiet for the proceedings of the surgeon,
the application of the chloroform must be considered successful, and
this condition proves the absence of pain even more completely than that
in which there is neither sign nor sound, except the breathing and
pulsation of the heart and blood vessels. A fourth condition of the
patient is that in which he is conscious, and can look on whilst the
surgeon is performing some small operation, or the minor part of a large
one, without feeling it, or whilst feeling it in a manner which is not
painful. This condition, when it occurs, is the most satisfactory proof
of the power of chloroform to prevent pain. It happens but rarely,
however, and cannot be induced at will, and it is usually at the
concluding part of an operation, during which the patient has been
unconscious, that this condition is met with. He wakes whilst there is
still a vessel to tie, or a suture to be introduced, and does not feel
it, owing, as was stated before, to some of the chloroform being
detained in the extra vascular liquor sanguinis, whilst the brain has
become almost free from the medicine. When the knife, or the needle, is
felt without being painful, it is because the common sensibility,
without being entirely abolished, is so much reduced, that what would
otherwise cause acute pain only occasions an ordinary sensation.