in accordance with the law explained above, rendered comparatively proof
against an amount of chloroform which would otherwise render it
insensible.
_Experiment 20._ A frog, which had been a few days previously subjected
to the experiment just narrated, was put into the same jar, which was
placed near the fire, till a thermometer inside marked 75° Fah.; 4·6
grains of chloroform were then introduced, and diffused through the air
in the jar. The jar was kept for twenty minutes, with the thermometer
indicating the same temperature within one degree. For the first
seventeen minutes, the frog was unaffected; and only was dull and
sluggish, but not insensible, when taken out. Air at 75°, when saturated
with vapour of chloroform, contains 22 per cent., and therefore the
0·383 per cent. of vapour, which at 55° was capable of saturating the
fluids of the frog to the extent of 1–26th of what they would dissolve,
was, at 75°, capable of saturating them only to the extent of 1–57th.
At one of Dr. Wilson’s Lumleian Lectures, at the College of Physicians,
on March 29th, 1848, I had the honour of performing some experiments,
and making some remarks, on chloroform, and I combined together two
experiments on frogs and small birds, in a way which shows how entirely
the effects of a narcotic vapour depend on the quantity of air with
which it is mixed, and on other physical conditions.
_Experiment 21._ I introduced a chaffinch, in a very small cage, into a
glass jar holding nearly 1,000 cubic inches, and put a frog into the
same jar, covered it with a plate of glass, and dropped five grains of
chloroform on a piece of blotting paper suspended within. In less than
ten minutes, the frog was insensible, but the bird was not affected.
_Experiment 22._ I then placed another frog and another small bird in a
jar containing but 200 cubic inches, with exactly the same quantity of
chloroform. In about a minute and a half, they were both taken out,—the
bird totally insensible, but the frog not appreciably affected, as from
its less active respiration it had not had time to absorb much of the
vapour.
The blood in the human adult is estimated by M. Valentin to average
about thirty pounds. M. Valentin’s experiments were so conducted that
this quantity must include the extra vascular liquor sanguinis, as well
as the blood actually contained within the vessels. On this account, his
estimate is all the better fitted for calculating the amount of
chloroform absorbed, since this medicine, when inhaled gradually, passes
by exosmosis through the coats of the bloodvessels into the fluid in
which the tissues are immediately bathed. The above quantity of blood
would contain 26 pounds 5 ounces of serum, which, allowing for its
specific gravity, would measure 410 fluid ounces. This being reduced to
minims, and multiplied by 0·0000614, the proportion of chloroform in the
blood required to produce narcotism to the second degree (see page 68),
gives 12 minims as the whole quantity in the blood. More than this is
used in practice, because a considerable portion is not absorbed, being
thrown out again when it has proceeded no further than the trachea, the
mouth and nostrils, or even the face-piece. But I find that if I put
twelve minims into a bladder containing a little air, and breathe it
over and over again, in the manner of taking nitrous oxide, it suffices
to remove consciousness, producing the second degree of its effects.
To induce the third degree of narcotism, or the condition in which
surgical operations are usually commenced, would require that about 18
minims should be absorbed by an adult of average size and health,
according to the above method of calculation; and to induce the deep
state of insensibility, which I have termed the fourth degree of
narcotism, would require 24 minims; whilst to arrest the function of
respiration would require that about 36 minims should be absorbed.
PREPARATIONS FOR INHALING CHLOROFORM.
The only direction which it is usually requisite to give beforehand, to
the patient who is to inhale chloroform, is to avoid taking a meal
previous to the inhalation; for chloroform is very apt to cause
vomiting, if inhaled whilst there is a quantity of food in the stomach.
The sickness is not attended with any danger, but it constitutes an
unpleasantness and inconvenience which it is desirable to avoid. The
best time of all for an operation under chloroform is before breakfast,
but the customs and arrangements of this country do not often admit of
that time being chosen, and it is unadvisable to make the patient fast
beyond his usual hour. It answers very well to perform an operation
about the time when the patient would be ready for another meal, or, if
the time of operation fall two or three hours after the usual time of
eating, to request the patient to make only a slender repast at that
time, so as just to prevent the feeling of hunger. It is impossible to
prevent vomiting in some cases with the best precautions, for the
stomach occasionally will not digest when the patient is expecting a
surgical operation, and the breakfast may be rejected in an unaltered
state hours after it has been taken. In other cases the patient does not
vomit, even when he inhales chloroform shortly after a full meal.
The most convenient position in which the patient can be placed whilst
taking chloroform is lying on the back, or side, as he is then duly
supported in the state of insensibility, and can be more easily
restrained if he struggle whilst becoming insensible. The semi-recumbent
posture on a sofa does very well, and there is no objection to the
sitting posture, when that is most convenient to the operator. In that
case, however, the patient should be placed in a large easy chair with a
high back, so that the head as well as the trunk may be supported
without any effort, otherwise he would have a tendency to slide or fall
when insensible. It has been said that it is unsafe to give chloroform
in the sitting posture, on the supposition that it would in some cases
so weaken the power of the heart, as to render it unable to send the
blood to the brain. Observation has proved, however, that chloroform
usually increases the force of the circulation; and although the
horizontal position is certainly the best for the patient under an
operation in all circumstances, I consider that the sitting posture is
by no means a source of danger, when chloroform is given, if the
ordinary precaution be used, which would be used without chloroform—that
of placing the patient horizontally if symptoms of faintness come on. I
have preserved notes of nine hundred and forty-nine cases in which I
have given chloroform to patients in the sitting posture, and no ill
effects have arisen in any of these cases.
The person who is about to inhale chloroform is occasionally in a state
of alarm, either about that agent itself or the operation which calls
for its use. It is desirable to allay the patient’s fears, if possible,
before he begins to inhale, as he will then be able to breathe in a more
regular and tranquil manner. In a few cases, however, the apprehensions
of the patient cannot be removed, and they subside only as he becomes
unconscious from the inhalation. It has been said that chloroform ought
not to be administered if the patient is very much afraid, on the
supposition that fear makes the chloroform dangerous. This is, however,
a mistake; the danger, if any, lies in the fear itself. Two cases will
be related hereafter in which the patients died suddenly from fear,
whilst they were beginning to inhale chloroform, and before they were
affected by it; but the probability is that, if they had lived till the
chloroform took effect, they would have been as safe as other patients
who inhaled it. If chloroform were denied to the patients who are much
afraid, the nervous and feeble, who most require it, would often be
deprived of its benefits. Moreover, the patients would either be
prevented altogether from having the advantage of surgery, or they would
be subjected to the still greater fear of the pain, as well as the pain
itself; for whatever undefined and unreasoning fears a patient may have
when the moment comes for inhaling chloroform, he has only chosen to
inhale it on account of a still greater fear of pain.
Fear and chloroform are each of them capable of causing death, just as
infancy and old age both predispose to bronchitis, but it seems
impossible that fear should combine with the effects of chloroform to
cause danger, when that agent is administered with the usual
precautions. Fear is an affection of the mind, and can no longer exist
when the patient is unconscious; but the action of that amount of
chloroform which is consistent even with disordered consciousness is
stimulating, and increases the force and frequency of the pulse, in the
same way as alcohol. I believe that no one would assert that a person
would die the sooner of fright for having taken a few glasses of wine,
or a small amount of distilled spirits, whatever might be the state of
his health. When chloroform has been absorbed in sufficient quantity to
cause unconsciousness, fear subsides, and with the fear its effects on
the circulation. It is a subject of almost daily observation with me
that the pulse, which is extremely rapid from some ill defined
apprehension, when certain patients begin to inhale chloroform, settles
down to its natural frequency after they become unconscious.
The practice I have always followed has been to try to calm the patient,
by the assurance that there was nothing to apprehend from the
chloroform, and that it would be sure to prevent all pain; but where it
has been impossible to remove the fears of the patient in this way, I
have always proceeded to remove them by causing a state of
unconsciousness. It would of course be wrong to choose a moment for
beginning the inhalation, when fear was producing a very marked
depression of the circulation. On feeling the pulse of a gentleman,
about twenty-one years of age, in March 1855, who had just seated
himself in the chair to take chloroform, previous to having some teeth
extracted, by Mr. Thos. A. Rogers, I found it to be small, weak, and
intermitting, and it became more feeble as I was feeling it. I told the
patient that he would feel no pain, and that he had nothing whatever to
apprehend. His pulse immediately improved. He inhaled the chloroform,
had his teeth extracted, woke up, and recovered without any feeling of
depression. Now if the inhalation had been commenced in this case,
without inquiry or explanation, the syncope which seemed approaching
would probably have taken place, and it would have had the appearance of
being caused by the chloroform, although not so in reality.
MODE OF ADMINISTERING CHLOROFORM.
The experiments previously related show that air containing rather less
than two grains of chloroform, in one hundred cubic inches, is capable
of causing a state of insensibility, sufficiently deep for surgical
operations; but in a creature the size of the human being, an
inconvenient length of time would be occupied in causing insensibility
with vapour so much diluted. About four cubic inches of vapour, or
rather more than five grains of chloroform to each hundred cubic inches
of air, is the proportion which I have found most suitable in practice
for causing insensibility to surgical operations. In medical and
obstetric cases, it should be inhaled in a more diluted form.
Dr. Simpson recommended chloroform to be administered on a
handkerchief—the method in which sulphuric ether was administered by Dr.
Morton, in the first case in which he exhibited that medicine. The
objection to giving chloroform on a handkerchief, especially in surgical
operations, where it is necessary to cause insensibility, is that the
proportions of vapour and of air which the patient breathes cannot be
properly regulated. Indeed, the advocates of this plan proceed on the
supposition that there is no occasion to regulate these proportions, and
that it is only requisite that the patient should have sufficient air
for the purposes of respiration, and sufficient chloroform to induce
insensibility, and all will be right.[53] The truth is, however, that if
there be too much vapour of chloroform in the air the patient breathes,
it may cause sudden death, even without previous insensibility, and
whilst the blood in the lungs is of a florid colour. Chloroform may
indeed be inhaled freely from a handkerchief without danger, when it is
diluted with one or two parts by measure of spirits of wine, but the
chloroform evaporates in largest quantity at first, and less afterwards,
until a portion of the spirit is left behind by itself. The process,
however, of inhaling chloroform from a handkerchief is always uncertain
and irregular, and is apt to confirm the belief in peculiarities of
constitution, idiosyncrasies and predispositions, which have no
existence in the patient.[54]
The most exact way in which it is practicable to exhibit chloroform to a
patient about to undergo an operation, is to introduce a measured
quantity into a bag or balloon of known size, then to fill it up by
means of the bellows, and allow the patient to inhale from it; the
expired air being prevented from returning into the balloon, by one of
the valves of the face-piece to which it is attached. I tried this plan
in a few cases, in 1849, with so much chloroform in the balloon as
produced four per cent. of vapour in proportion to the air. The effects
were extremely uniform, the patients becoming insensible in three or
four minutes, according to the greater or less freedom of respiration;
and the vapour was easily breathed, owing to its being so equally mixed
with the air. I did not try, however, to introduce this plan into
general use, as the balloon would sometimes have been in the way of the
surgeon, and filling it with the bellows would have occasioned a little
trouble. It seemed necessary to sacrifice a little of absolute
perfection to convenience, and I therefore continued the plan which I
had already followed.
The great point to be observed in causing insensibility by any narcotic
vapour, is to present to the patient such a mixture of vapour and air as
will produce its effects gradually, and enable the medical man to stop
at the right moment. Insensibility is not caused so much by giving a
dose as by performing a process. Nature supplies but one mixture of
diluted oxygen, from which each creature draws as much as it requires,
and so, in causing narcotism by inhalation, if a proper mixture of air
and vapour is supplied, each patient will gradually inhale the requisite
quantity of the latter to cause insensibility, according to his size and
strength. It is indeed desirable to vary the proportions of vapour and
air, but rather according to the purpose one has in view, whether
medicinal, obstetric, or surgical, than on account of the age or
strength of the patient; for the respiratory process bears such a
relation to the latter circumstances, as to cause each person to draw
his own proper dose from a similar atmosphere in a suitable time.
The inhaler represented in the adjoining engraving is, with some slight
alterations, the same that I have employed since the latter part of
1847. It is made of metal, and consists of a double cylinder, the outer
space of which contains cold water, and the inner serves for the
evaporation of the chloroform which the patient is to breathe. Into the
inner part of the cylinder there is screwed a frame, having numerous
openings for the admission of air, and four stout wires which descend
nearly to the bottom of the space, and are intended to support two coils
of stout bibulous paper, which are tied round them, and reach to the
bottom of the inhaler. In the lower part of this paper four notches are
cut, to allow the air to pass in the direction indicated by the arrows.
As the quantity of chloroform which is put in should never fill the
apertures or notches, the air which passes through the inhaler meets
with no obstruction whatever. There is a glass tube communicating with
the interior of the inhaler, and passing to the outside, to enable the
operator to see when the chloroform requires to be renewed. The elastic
tube which connects the inhaler to the face-piece is three-quarters of
an inch in internal diameter, to allow of the passage of as much air as
the patient can possibly breathe. On the introduction of the practice of
inhaling sulphuric ether there was no tubing in this country fit to be
breathed through; that in ordinary use was only about one-third, or
three-eighths of an inch in diameter,—not more than a quarter of the
proper calibre.
[Illustration]
The face-piece, to include both the mouth and nostrils, of which that
shown in the engraving is one of the modifications, is one of the
greatest mechanical aids to the process of inhalation which has been
contrived in modern times. Dr. Francis Sibson is its inventor. Dr.
Hawkesley did indeed contrive a very similar one about the same time as
Dr. Sibson,—early in 1847,—but he did not make it known. Dr. Ingen Housz
made patients inhale oxygen through the nostrils by means of a bottle of
India rubber with the bottom cut off; and Mr. Waugh, of Regent Street,
had more recently contrived a mouth-piece to be adapted outside the
lips, but the usual practice of inhalation previous to 1847, was for the
patient to draw in the medicated air by means of a tube placed in the
mouth. This led generally to great awkwardness at first, as the patient
usually began to puff as if he were smoking a pipe; and it had the
further inconvenience, in the administration of ether, that the tube
dropped from the mouth, and the patient began to breathe by the
nostrils, just as he was getting unconscious. The sides of the
face-piece delineated in the engraving are made of thin sheet lead,
which is pliable, and enables it to be adapted exactly to the
inequalities of the face, and the patient can breathe either by the
nostrils or mouth, just as his will, or instinct, or other nervous
functions, determine.
I have introduced two valves into this face-piece, one which rises on
inspiration, to admit the air and vapour from the inhaler, and closes
again on expiration, and the other which rises to allow the expired air
to escape. I contrived the latter valve to turn more or less to one
side, as indicated by the additional line in the engraving, and thus
admit more or less of the external air to dilute still further that
which has passed through the inhaler, and become charged with vapour. By
this means the patient can begin by breathing air containing very little
vapour, and more and more of the air which has passed over the moistened
bibulous paper can be admitted, as the air-passages become blunted to
the pungency of the vapour.
The object of the water-bath is to supply the caloric which is rendered
latent, and carried off, as the chloroform is converted into vapour, and
thus to render the process of inhalation steady and uniform. Without the
water-bath, the evaporation of the chloroform would soon reduce the
temperature of the inhaler below the freezing point of water, and limit
very much the amount of vapour the patient would inhale; and if the
apparatus were warmed by the hand, the temperature would be too high,
and the amount of vapour too great. A medical author of great reputation
in Paris sent to inquire at what temperature I used the water-bath, and
being informed, at the ordinary temperature, published his opinion that
it had no effect, and might as well be left off. He appeared not to have
considered the relations of heat, either to liquids or vapours.
In arranging the bibulous paper in the inhaler, it is my object to
contrive that the air passing through, in the ordinary process of
inhalation, and at the ordinary temperature of about 60°, shall take up
about five per cent. of vapour. This quantity can be diminished, as much
as is desired, by turning the expiratory valve of the face-piece a
little to one side; and in winter I usually place a short coil of
bibulous paper against the outer circumference of the inside of the
inhaler, in addition to the central coils which are delineated.
I commonly put two, or two and a half, fluid drachms of chloroform into
the inhaler at first. About a drachm of this is absorbed by the
filtering paper, and the rest remains at the bottom of the inhaler; and
in a protracted operation, when it is seen, by means of the glass tube,
that the latter part of the chloroform has disappeared, more is added,
by a drachm or so at a time, to prevent the paper ever becoming dry. Mr.
Matthews, 8, Portugal Street, Lincoln’s Inn Fields, makes the inhaler.
There are smaller face-pieces for children. The patient never inhales in
so upright a posture as the artist has represented.
There are several other kinds of apparatus in use for the inhalation of
chloroform. The most usual consist of Dr. Sibson’s face-piece more or
less altered, and with a small piece of sponge placed inside. The
apparatus which is in most reputation on the continent is that of M.
Charrière; it consists of a glass vase with suitable valves, and a
fabric for exposing a surface wetted with chloroform to the air which
passes through it.
M. Duroy, of Paris, has contrived an ingenious, but very complicated,
apparatus, which he calls an anæsthesimeter. The object of it is to
regulate the amount of chloroform which is inhaled in a given time, and
this can be varied from four to sixty drops in the minute; but the
experiments which I have related show that the quantity of chloroform
employed is not so important as the proportion of it in the inspired
air; and although each of these circumstances has considerable influence
over the other, in many cases there are conditions in which no regular
relation exists between them. For instance, if the inhaler were supplied
with sixty drops of chloroform per minute, these sixty drops weigh
twenty grains, and produce 15·3 cubic inches of vapour; and if an adult
patient were breathing the average quantity of four hundred cubic inches
per minute, the air he would breathe would contain nearly four per cent.
of vapour, which would answer extremely well; but if the breathing were
slow or feeble, or if he should hold his breath for an interval and
commence again, he might breathe air much more highly charged with
vapour. Indeed it would depend on the amount of surface moistened with
chloroform, the temperature of the air, and other physical conditions,
whether or not the air he inhaled might not be charged with chloroform
to a dangerous degree; whilst, on the other hand, if the breathing were
deep and rapid, as often happens whilst the patient is getting slightly
under the influence of the chloroform;—if, for instance, the patient
were to breathe at the rate of 1,600 cubic inches, instead of 400, the
air he would inhale would contain less than one per cent. of vapour, and
he would not become insensible with the utmost supply of the
anæsthesimeter, till his breathing should be moderated. M. Duroy also
follows the rude and objectionable plan of using a nose clasp, and thus
compelling the patient to breathe by the mouth alone.
It is advisable to request the patient to breathe gently and quietly,
when he commences to inhale chloroform; in other words, to do nothing
but conduct himself as if he were about to fall asleep naturally; for,
if he breathes deeply, the vapour feels much more pungent than it
otherwise would do, and is apt to excite coughing, or a feeling of
suffocation.