Source:  Snow, John. Lancet, Oct. 20, 1855, pp. 361-363 (Part 1), Oct. 27, 1855, pp. 383-385 (Part 2).

On the employment of chloroform in surgical operations

By John Snow, M.D.

Part 1

I have now been very much occupied in the administration of chloroform for a period of nearly eight years; and I am quite confirmed in the opinion which I long ago expressed, that this agent may be exhibited with propriety in every case in which the patient requires, and is in a condition to undergo, a surgical operation. If it were simply a question of giving chloroform or not giving it, there are, indeed, some patients to whom one would prefer not to give it; but the question lies between exhibiting chloroform or inflicting the pain of an operation, and, according to my observation, the former is always the lesser evil of the two. The affection which is generally thought to be most opposed to the inhalation of chloroform is fatty degeneration of the heart; but from all that I have been able to observe, it is of great advantage, in such cases, to prevent the pain of an operation.

Patients with fatty degeneration of the heart are liable to die suddenly in two distinct ways: first, with the cavities of the heart empty; and, secondly, with the cavities of the heart full of blood. In the latter case, death is caused by the inability of the weakened heart to propel the blood; but, in the former case, where the patient dies by ordinary syncope, such as that occasioned by loss of blood, and where the cavities of the heart are empty, death must be caused by some undescribed condition which accompanies the disease of the heart, and not by that disease itself; for the most healthy heart would be unable to maintain the circulation when the blood no longer reached its cavities from the veins.

The pain of a surgical operation has a tendency to produce both those conditions of the cavities of the heart which are liable to prove fatal, when that organ is affected with fatty degeneration; whilst, on the other hand, chloroform has the effect of keeping the circulation in a more equable state. The ordinary kind of syncope, in which all the cavities of the heart are probably empty, was very common during surgical operations, before the introduction of ether and chloroform, even when the patients were apparently strong, and the operation of a trifling nature. Under the influence of chloroform, however, syncope is extremely rare, even in operations attended with considerable loss of blood. The pain of an operation has a tendency also, in many cases, to cause over-distention of the right cavities of the heart, owing to the patient straining violently, and holding his breath. The following instance, in which I had an opportunity of witnessing a similar operation, in the same patient, both with and without chloroform, shows this effect of pain, and the favourable effect of anæsthesia, in a remarkable manner.

On January the 6th, 1855, Mr. Fergusson performed lithotrity in King's College Hospital, on a man aged fifty-one. He generally directs chloroform to be administered in lithotrity, but in this instance he omitted to do so, as he thought that the bladder was not very irritable, and that the patient would not suffer much. I began to feel the pulse just when the patient saw the lithotrite about to be introduced. It was 120 in the minute. As soon as the instrument was introduced, the pulse increase to 144, and immediately afterwards it became uneven, irregular, and intermitting. I could not count more than three or four beats at a time, and, occasionally, when the pain seemed greatest, and the man was straining and holding his breath, the pulse at the wrist was altogether absent for four or five seconds at a time. In order to ascertain whether the absence of pulse might not depend on the pressure of the muscles of the arm, caused by grasping the table, I applied my ear to the chest, and found that there was no sound whatever to be heard during the intervals when the pulse was imperceptible. It was evident that the patient held his breath till the right cavities of the heart became so distended as to stop the action of that organ till the respiration returned. The man did not complain, or cry out, during the operation. A week afterwards the lithotrity was repeated, but on this occasion I administered chloroform. The pulse was about 120 in the minute, when the patient began to inhale; but it became slower as he was made unconscious, and it was regular and natural during the operation. It was only towards the end of the operation, when the effect of the chloroform was allowed to diminish, and the man began to strain a little, though not yet conscious, that the pulse intermitted slightly, passing over a single beat occasionally. There were none of the long intermissions of the pulse which were observed on the former occasion.

It is very evident, that if this patient had been the subject of any affection of the heart which weakened or embarrassed its action, he would have run a much greater risk from the pain of the first operation than from the inhalation of chloroform in the second one.

I have given chloroform with a favourable result to a great number of patients having all the symptoms of fatty degeneration of the heart, as a weak, intermittent pulse, arcus senilis of the cornea, and liability to faintness. The only patient, indeed, whom I have had the misfortune to lose whilst inhaling chloroform had very extensive fatty degeneration of the heart, the symptoms of which were well marked during life; but I am by no means sure that this patient died from the effects of chloroform, although I thought it best at the time to designate the death as one from this agent. The patient, a gentleman aged seventy-three, died just as he probably would have done, at no distant day, if no surgical or medical interference had taken place. He was making a straining effort, as if he was beginning to feel the pain of the operation, and I was commencing to give him a little more chloroform, when he suddenly expired; and I am quite unable to tell whether it was the effort of straining, or the influence of the chloroform, which caused death to take place at the moment when it did. The quantity of chloroform he was taking at the time was very small indeed, and largely diluted with air, and he had inhaled it several times before. But if it be granted that this death was caused by the chloroform, when I take into account the number of other patients with similar symptoms, to whom I have given it with a favourable result, I do not consider that it furnishes any argument against the use of this agent in such cases. Patients with fatty degeneration of the heart in an advanced stage are, no doubt, very undesirable subjects for a surgical operation under any circumstances; but when it is absolutely necessary to perform one, I am of opinion, both from what I have seen of the effects of pain on the circulation, and from what I have seen of the effects of chloroform in patients of this kind, that it is desirable to let them have the advantage of its administration. Patients with symptoms of fatty disease of the heart sometimes become faint after the conclusion of an operation under chloroform if they are kept in a sitting posture, but I have always found the faintness to subside on placing them horizontally. [361/362]

Out of the entire number of deaths from chloroform which are recorded, there are very few in which any considerable disease of the heart was found. In fact, the majority of those who are dead from chloroform were healthy persons in the best period of life--that is, from fifteen to thirty-five or forty, and it is most likely that they had, on the average, a sounder state of the heart than the multitude who have inhaled chloroform with impunity. It was not very uncommon occurrence for patients to die on the operating table before the introduction of anæsthesia, either just before the commencement of an operation or during its performance. Dr. Simpson, writing in 1852, says that two deaths had occurred on the operating-table in Edinburgh since the discovery of the effects of chloroform, in cases where the agent was not used. One died directly after the first incision through the skin, in a case of hernia, and the other instantly after the use of an abscess lancet. He also alludes to a case which occurred in Edinburgh just before the introduction of chloroform. Dr. Robertson had shaved the groin of a patient, and was proceeding to perform the operation for hernia, when the patient fainted, and died before any incision was made.

We have no information respecting the state of the heart in the patients who died suddenly on the operating table before the introduction of ether and chloroform, but it is extremely probably that many of them were affected with fatty degeneration of this organ; and I believe that by the careful administration of chloroform during operations on such patients, we not only prevent pain, but may in some cases save life.

The sudden deaths which occasionally took place on the operating table, before the introduction of anæsthesia, have sometimes been alluded to as affording an explanation of the deaths that have occurred during the use of chloroform; but, with a very few exceptions, this is not a correct view of the subject. In the instance at Mr. Robinson's, and in that at St. George's Hospital, the patients appeared to die suddenly from mental emotion, without being affected by the chloroform, which they were only just beginning to inhale; and in three cases on the Continent, where the patients died suddenly, just after great operations, loss of blood was probably the cause of death. With these, and perhaps one or two other exceptions, the deaths that have taken place under the influence of chloroform have nothing in common with those which happened on the operating-table before its introduction. In these latter cases, if the death did not arise from hæmorrhage, it was occasioned either by pain or mental emotion; but as the patient neither feels nor thinks when fully under the influence of chloroform, he cannot die from either of the two latter causes. In speaking of the benefits of chloroform, it is quite allowable to bring forward the sudden deaths which occasionally happened in operations, as a set-off against the deaths from this agent; but to suppose that the patients who have died during the employment of chloroform are the same that would have died without it is undoubtedly a mistake. The late Dr. Richard Mackenzie related a case of sudden death, which, he said, narrowly escaped being imputed to chloroform. He reduced a fracture of the radius, about an inch above the wrist, in a case where there was a good deal of swelling and displacement. He would have used chloroform, but he had none with him. Within five minutes after Dr. Mackenzie left the house, the patient died instantaneously, whilst he was talking freely to those about him. He was a corpulent man, from sixty-five to seventy years of age, who had lived freely, and Dr. Mackenzie thought it probable that he had fatty degeneration of the heart, but there was no examination of the body. The cause of death, in this case, was probably the pain to which the patient had been subjected, and it is not unlikely that the employment of chloroform might have saved his life for a time. At all events, there is no reason to conclude that the patient would have died in the manner he did if chloroform had been administered.

Surgical operations are, I believe, never performed during acute disease of the lungs, and chronic affections of these organs, as phthisis and chronic bronchitis, form no objection to its use. I have administered this agent in a number of operations where one or other of these diseases was present, and there have been no ill consequences in any case. The mucous membrane of the air-passages is always irritable, both in consumption and bronchitis, and the chloroform is apt to excite coughing at first. It is therefore necessary to begin by giving the vapour very gently in these cases, and in a little time the irritability of the mucous membrane is allayed, and insensibility can always be induced in a few minutes. The cough is afterwards relieved, in nearly all these cases, for a time--often for two or three days, in cases of chronic bronchitis.

Affections of the head offer no obstacle to the exhibition of chloroform in surgical operations. I have given it in many cases where more or less paralysis remained, from previous attacks of apoplexy, and no ill effects have followed. In a patient on whom Mr. Robert Wade lately operated--removing a scirrhous tumour of the labium pudenda--there was probably disease of the heart, as well as the remains of an apoplectic clot in the brain. The age of the patient is seventy-two; she is partially hemiplegic, from an apoplectic seizure two years ago; and her pulse, when I saw her, was irregular in the strength of its beats, and also intermitted. She went through the operation very well, and readily recovered her consciousness. I saw Mr. Wade eleven days after the operation, and learned that his patient was going on well. There is often some trouble in giving chloroform to insane patients, for when they cannot be persuaded to inhale it, it has to be given by force. When once they are under its influence, however, the surgeon is enabled to make examinations, and to perform operations that would otherwise be impossible.

I have given chloroform to a number of patients who were reduced to a state of extreme debility, from chronic disease of the large joints, and from various other causes. Chloroform agrees extremely well with such patients; they do not require to inhale so much as stronger persons, but that forms no difficulty, as the administration of this agent does not consist in giving a dose, but in executing a process, and the effects produced are observed as the process goes on.

An objection was raised in the Crimea last autumn to the use of chloroform in operations immediately succeeding to severe gun-shot wounds; but this objection seems to have given way before further experience. According to the letter of a medical officer, quoted in the medical journals, this agent was used with very good effect in such cases in particular where the soldier had the left thigh shattered to pieces, the right hand and wrist joint in the same condition, and a compound fracture of the other arm. Amputation of the thigh and forearm was performed, and, when sent to Sentari, two days afterwards, the patient promised to do well. The writer was of opinion that the soldier could hardly have borne the shock of his wounds and the operation without chloroform. I have not had occasion to give chloroform in operations immediately after gun-shot wounds, but after severe compound fractures from other causes, I have found its action very satisfactory, as well as in strangulated hernia, where there was excessive exhaustion.

I have often administered chloroform during pregnancy and no ill effects have followed in any case. Mr. Fergusson, Mr. Bowman, Mr. Henry Charles Johnson, and Mr. B. Travers, jun., are some of the surgeons for whom I have given chloroform to patients undergoing operation during pregnancy.

Chloroform may be given with propriety to patients of all ages. I have exhibited it to several infants aged from ten days to three weeks, and to one patient nearly ninety. I have notes of the cases of 145 infants under a year old, to whom I have administered this agent. A great number of them were operated on for hare-lip by Mr. Fergusson, who performs this operation at the earliest period of life, if the children are healthy. Chloroform acts very favourably on infants and children. There has, I believe, been no death from chloroform under the age of fifteen years. Chloroform was, indeed, blamed for the death of a child, in Germany, during the removal of a very large nævus on the side of the face, but there is no doubt that the cause of death in that case was hæmorrhage.

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 when there is much 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 not advisable 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 the 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 this feeling of hunger. It is impossible to prevent vomiting, in some cases, with 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. [362/363]

The most convenient position in which the patient can be placed whilst inhaling 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 should struggle whilst becoming insensible. The semi-recumbent posture on a sofa, also, 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 could 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 and 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 a 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 647 cases in which I have given chloroform to patients sitting in a chair, 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 the 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 were alluded to above, 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 have 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. 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. As soon as this is induced, the pulse, which just before may have been extremely frequent and small, from the effects of fear, generally falls almost to its natural frequency, and resumes its full volume and force.

As a general rule, it is best to place the patient in the position in which the operation will be performed before he inhales the chloroform; but in cases of disease of the large joints, and other instances where motion causes pain, it is an advantage to give the chloroform to the patient in bed before he is removed to the operating-table. It is often desirable also to give it to children in another room, that they may not see any of the preparations for the operation.

Part 2

It is unnecessary to say anything on the propriety and advantage of administering chloroform in lithotomy, in the larger amputations, and the removal of tumours of the breast, for I believe the whole of the profession agree on this point. There is still, however, some difference of opinion as to the propriety of giving it in lithotrity. It has been said that the surgeon requires the assistance of the patient's sensations, to prevent him from seizing the coats of the bladder in the lithotrite; but if this were the case, I believe that the operation could never have been performed at all. Some patients cry out when they are scarcely touched, whilst others will bear the greatest torture without a murmur. I believe there is very little danger, or even possibility of seizing the bladder with the lithotrite, and that, even if this should take place, the surgeon's sense of touch would be the proper guide to prevent mischief. The greatest sensibility of the bladder appears to be at the neck and it may fairly be doubted whether seizing the mucous membrane of the cavity would cause much pain. It has always appeared to me that the operation of lithotrity is one in which chloroform prevents very great suffering, and is of the utmost advantage. I will, however, quote the opinion of one who has had much practice in lithotrity both before the introduction of anæsthetic surgery and since, and is therefore better able to judge. Mr. Fergusson says, in his Practical Surgery,* "I am of opinion that there is not any department in practical surgery in which anæsthesia has been of more service than in this. Since the earliest period of its introduction I have almost invariably used it on such occasions, and with the best possible effects; and now I no more think of performing the operation of lithotrity without this agent than I would that of lithotomy." (*Third edition, p. 800.) Many other surgeons are of the same opinion as Mr. Fergusson, and some of those who are disinclined to use it as a general rule, practically admit its benefits by resorting to its employment in cases where the urinary passages are very irritable, or the patient very intolerant of pain. The operation of lithotrity requires a pretty full dose of chloroform, as, without this, the patient is apt to strain very much and move his legs about.

Some surgeons, and more especially those of Edinburgh, had an objection, at one time, to employ chloroform in large operations about the mouth and nose, and especially in the removal of tumours of the jaw, for fear the blood should flow into the windpipe during the state of insensibility and cause suffocation. However, I have given chloroform in a great number of such cases without any ill effects. Unless the effects of the chloroform are too deep or long-continued, the sensibility of the glottis is not impaired; if a little blood enters the windpipe, it is coughed out again; the patient can hold a little blood in his throat, and breathe through it with a gurgling noise, just as he would in the waking state; and if the quantity of blood begins to embarrass the breathing, the head must be leaned forward to get rid of it, and the same attention paid to the patient which would be paid if chloroform were not used. After the commencement of an operation of this kind, a little chloroform may be given from time to time, on a sponge, as opportunity permits, so as to keep up the insensibility to some extent. I prefer, under these circumstances, to have the chloroform diluted with spirit, in the manner and for the reason that I shall mention further on, in treating of its use on a handkerchief.

A case has been related by Mr. Prescott Hewett, in the Medico-Chirurgical Transactions, (vol. xxxiv., p. 43.) in which a patient died about half an hour after the removal of the greater portion of a tumour of the upper jaw. He was previously much reduced by hæmorrhage from the tumour, and he fainted before the operation was concluded. He remained much exhausted till the period of his death, though quite conscious. The breathing was not embarrassed until he was moribund, at which time a little blood, which was still oozing from the remains of the tumour was drawn into the trachea, as I was informed by a surgeon who was standing by at the time. This circumstance gave rise to some small spots of ecchymosis, which were found in the lungs after death. It was suggested that in this case blood might have got into the lungs during the insensibility from chloroform, and so have been the cause of death. But, in the first place, the symptoms which were observed during the operation, and for some time afterwards, were simply those of syncope, and not of embarrassed breathing; and, again, the amount of blood met with in the lungs was not enough to cause death, or even acute symptoms of any kind.

Extraction of cataract is an operation in which surgeons hesitated for a long time before employing chloroform. They were afraid lest the vomiting which sometimes attends or follows the use of this agent might be injurious to the eye. Mr. George Pollock and Mr. White Cooper were, I believe, the first surgeons who adopted the use of chloroform in the extraction of cataract; and I have since administered this agent also in many operations of this kind for Mr. Lawrence, Mr. Bowman, Mr. Haynes Walton, and others. Several of the patients were considerably over eighty years of age. By taking care not to give the chloroform too soon after a meal, there has very seldom been vomiting; and although a little vomiting has taken place in a very few of the cases, it was not attended by straining, and, as I understand, did not do harm in any case. I have, indeed, been informed of a case, at which I was not present, where chloroform was given, and where the patient vomited and expelled the humours of the eye; but she was a person of bad constitution, and such accidents did occasionally happen before the use of chloroform. In some cases, where the patient is very nervous, and the eye very irritable, I believe that chloroform is essential to the success of the operation, but it is not necessary to use it in all cases. I understand from Mr. Bowman that his practice is to operate without chloroform in cases where the patient does not wish for it, and has resolution to lie still, and keep the eye steady. The operation is said to be not very painful, but it is one which has a great tendency to rouse the patient, if he is not very insensible; it is necessary therefore to induce complete insensibility, and to keep it up till the lens is extracted, as the least movement of the patient might be prejudicial.

Operations about the anus generally require a full dose of chloroform, as the part is very sensitive when in a state of disease, and the patient, if not quite insensible, has a tendency to move his legs, which is very embarrassing to the surgeon, [383/384] especially if there is no one to hold them. It was feared at one time that there would be a difficulty in operating for hæmorrhoids under chloroform, as the patient is often required to press them down; but it is found that if he do so beforehand, and whilst he is beginning to inhale, the bowel remains down; in fact, there is a great tendency to make a straining effort under the influence of chloroform, when the rectum is the seat of operation. Mr. Salmon thinks that the vessels of the rectum bleed rather more during operations under chloroform than without it, owing to the relaxation or diminished contraction of the sphincter; but I have not heard other surgeons make the same remark.

With respect to the deaths which unfortunately take place, now and then, from chloroform, many medical men have supposed that they are to be avoided by carefully selecting the cases for its administration; and declining to give it in certain affections, especially of the heart; whilst others, remarking that the deaths have often occurred in persons apparently the most healthy, acknowledge that they are not to be avoided by selecting the patients, but consider that they nevertheless depend on some peculiarity in the constitution which is not to be discovered beforehand. This is a more melancholy conclusion than the former, as it invests the chloroform with some amount of danger in all cases. It meets with apparent support at first sight, however, in the circumstance that some patients have died from a very small quantity of chloroform, whilst in numerous instances a large quantity has been used without ill effects. A little further inquiry shows, however, that several of the patients who died from chloroform had inhaled it previously in as great quantity without ill effects; and in the case of Samuel Bennett, which occurred in Westminster, in February, 1849, half an ounce of chloroform was used without causing insensibility, and when a fresh supply was obtained and administered, two hours afterwards, he suddenly expired. But it cannot be supposed that a person would have a peculiarity of constitution at one time which he did not possess at another, especially within the space of two hours.

In two papers which I had the honour to read to the Medical Society of London* a few years ago, it was shown that the deaths which had taken place from chloroform were occasioned by the sudden arrest of the action of the heart by this agent, and this is equally true of the deaths which have since occurred. (*See Edin. Med. and Surg. Journal, No. 180, and London Journal of Medicine, 1852.) To stop the action of the heart by the direct action of chloroform, there requires to be a larger proportion of it present in the blood than suffices to arrest the action of the muscles of respiration, and, therefore, if the vapour were always inhaled in a very regular and gradual manner, it would be impossible for it to paralyse the heart by its direct influence; for the breathing would first cease, and the action of the heart would only be brought to a close by the absence of the respiration, as in asphyxia. But as the heart is the first organ which the chloroform reaches after it is taken into the lungs, the coronary arteries being the first branches given off from the aorta, it is possible, if the vapour inhaled be too strong, that the heart may receive an overdose. When animals are made to breathe air containing four or five per cent of vapour of chloroform till death ensues, the breathing ceases first, and the heart continues to beat for a minute or two longer. During this interval life can easily be restored by means of artificial respiration, and the animals sometimes give one or two gasps at the moment when the heart is ceasing to beat, which may restore the action of that organ, and bring about recovery, if the animal have been removed from the chloroform. On the other hand, when animals are made to breathe air, containing eight or ten per cent of the vapour, death takes place suddenly, the motion of the heart ceasing at the same time as the breathing, or even before it. It requires a little contrivance to make the air on all occasions take up as much as eight or ten per cent of vapour of chloroform, and this explains not only how accidents may happen, but also why they happened so rarely, even when no regard is had to the amount of vapour in the air breathed by the patient. According to experiments, which I related on a former occasion, the amount of chloroform required to stop the action of the heart is one-eighteenth part as much as the blood will dissolve, or one part of chloroform to about 5,184 parts of serum of blood. The actual quantity of chloroform, therefore, which, by acting locally on the heart, arrests its motion, and causes a sudden accident, is very little more than a quarter of a minim. Consequently it need excite no surprise that the amount of chloroform which has been used in cases where accidents have occurred has been extremely variable. The danger from chloroform bears very little relation to the quantity used. In fact, to make an adult patient insensible with half a drachm is not so safe as to use a drachm in the process, if it be used judiciously; for in the former case the air must be more highly charged with vapour than in the latter. Exhalation of chloroform is always going on at the same time as inhalation, and to cause insensibility with vapour largely diluted, a larger quantity of it must be used than when it is less diluted.

I have already expressed the opinion that chloroform may be given to every patient requiring an operation without increasing the danger, whatever his condition may be; and have now to add, that the danger from chloroform, when it does exist, is as great to the strong and healthy as to the feeble and diseased. In fact, it is precisely in the most strong and robust persons that, according to my belief, the greatest care is required in giving chloroform. Robust lean persons, accustomed to hard work or athletic sports, require the narcotism of the nervous centres to be carried further than in the feeble, fat, or sedentary, before they will lie still under the use of the knife; and they are also very apt to struggle and become rigid after they are made unconscious, but before being insensible. During this state of struggling and rigidity they often hold the breath for a considerable time, and then suddenly draw a deep inspiration; and, if the vapour of chloroform is not presented in a very diluted form, a large quantity of it may be drawn into the lungs all at ounce, at a time when the pulmonary circulation is probably much retarded from the temporary suspension of respiration. In this way the portion of blood passing through the lungs at the moment may be so overcharged with chloroform as suddenly to paralyse the heart. In a considerable number of the fatal cases of inhalation of chloroform, the patient has expired suddenly whilst he was struggling in an involuntary manner.

The danger which exists in giving chloroform is simply that the patient should be allowed to breathe air too highly charged with vapour; for when the vapour is sufficiently diluted its effects takes place so gradually that no medical man can mistake them, and proceed to give an overdose. A very prevalent error respecting chloroform is to suppose that the patient is safe as long as he gets sufficient air for the purposes of respiration, whilst the truth is that the more air a person breathes the greater is his danger, if the air happens to be over highly charged with vapour. I have not space, in this paper, to enter on mode of operation of narcotic vapours, but, in order to show that narcotics, in a gaseous form, do not produce their effects by mechanically excluding the air, it is only necessary to allude to two or three well known agents of this class. Thus, whilst air containing eight per cent of vapour of chloroform cannot be inhaled without danger, air containing four or five times as much vapour of ether may be breathed with the utmost impunity. Nitrous oxide gas may be breathed when diluted only with the air which is present in the lungs at the beginning of the experiment; whilst the vapour of hydrocyanic acid requires to be diluted with several hundred times its volume of air before it can be inhaled without danger.

The means which I use to prevent the air breathed by the patient being too highly charged with vapour, is an inhaler which I have described on a former occasion. I cannot with a handkerchief regulate the amount of vapour and of air in the manner that is desirable; but I consider that those who prefer to give chloroform on a handkerchief may do so without danger though with no great accuracy, if they dilute the chloroform with rectified spirit. Either two parts by measure of spirit to one of chloroform, as recommended by Dr. Warren, of Boston in America, or equal parts of each, answer very well. Very little of the spirit is inhaled; it remains behind on the handkerchief, but it has the effect of lowering the elastic force of the vapour of chloroform, and thereby diminishing the amount of the vapour that the air will take up under the same physical circumstances.

In whatever way chloroform is given, it is necessary to begin gently at first, in order to accustom the mucous membrane of the air-passages to the pungency of the vapour, and to increase the strength of the vapour by degrees. I usually take two or three minutes in children and about four minutes in the adult to produce insensibility; but in robust, muscular subjects, who struggle much, it is sometimes desirable to proceed so cautiously as to take seven or eight minutes. In giving chloroform, it is best to observe every symptom exhibited by the patient; but the sensibility of the edge of the eyelid is the best test of the general sensibility. When the ciliary border may be touched without causing winking, or with very slight winking, the knife may in nearly all cases be used without causing a flinch or a cry. The state of the breathing is the best guide against carrying the effects of the chloroform too far. If it beings to [384/385] be stertorous, it is advisable to suspend the inhalation. The pulse is of less consequence than many of the other signs; for if the chloroform be properly diluted with air, it cannot seriously affect the pulse, and if it be not the pulse might cease suddenly. Its last beat in some of the accidents which have happened has been equal in strength to any which went before.

It is impossible in a brief space to allude to more than a few of the points connected with the use of chloroform in operations. I have therefore passed over most of those points on which I believe the profession are entirely agreed, and have treated chiefly on those respecting which I considered that my views might differ from those of, at all events, some of my professional brethren, in order that there might be the more room for the expression of opinion and experience.

Sackville-street, October, 1855.

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