Source:  Snow, John. Med. Times and Gazette 7 (1853): 485-86. [ltr. to ed., 5 November 1853]

The late deaths from chloroform

To the Editor of the Medical Times and Gazette

Sir,--The late deaths from chloroform, occurring nearly at the same time in different public institutions, have naturally attracted considerable attention; and they seem to call for some inquiry, whether means may not be adopted to prevent such accidents, or, at all events, render them of more rare occurrence. In concluding his account of the late fatal case at St. Bartholomew's Hospital, your reporter says:--"It is mournful, indeed, to consider, that, from cases such as the last three or four which it has been our lot to record, the practical surgeon gains no knowledge calculated to authorise the hope, that in future the like tragedies will be of less frequent occurrence." The case at St. Bartholmew's Hospital might at first sight seem to justify and require these observations, for the chloroform was administered by a medical man of eminence appointed to the duty, and in the constant habit of performing it. The vital organs of the patient were all sound, and she had taken the chloroform before without ill effects. There are circumstances, however, which lead me to a different conclusion from that of your reporter.

When the air a person breathes does not contain more than 4 or 5 per cent of vapour of chloroform, insensibility is induced very gradually; and I have found in numerous experiments on animals, that when vapour of this strength is continued till they are destroyed, death takes place very slowly. The breathing first becomes embarrassed, and then ceases; but the heart continues to beat for one or two minutes afterwards. During this interval, the animal can be easily restored by artificial respiration; and it often happens that, when the action of the heart is about to cease, the animal makes a gasping inspiration or two, which renew the circulation and cause spontaneous recovery if the chloroform is not continued. On the other hand, when animals are made to breathe air containing 8 or 10 per cent or upwards of chloroform, death takes place very quickly, and the circulation of the blood is arrested at the same time as the breathing, and, indeed, in some cases, before the breathing. A very few inspirations of air, containing 10 per cent of vapour of chloroform, have the effect of paralysing the heart, as I ascertained by giving chloroform to rabbits, by means of artificial respiration, after the chest was laid open.* (*See London Journal of Medicine, April, 1852.)

Now, on examining the history of all the recorded cases of death from chloroform, it is ascertained, that the fatal event did not arise, in any instance, from the too long administration of vapour sufficiently diluted with air. In all the cases, the circulation has been arrested by the immediate action of the chloroform, owing to the circumstance, that the air which the patient was breathing just before he died or became moribund, has been too highly charged with vapour. It is evident, therefore, that the first consideration in giving chloroform should be, to take care that the vapour contained in the air which the patient is breathing shall at no time much exceed five per cent. So far from this being the case, however, it is seldom that any thought is taken of the quantity of vapour in the air breathed by the patient. It is generally considered sufficient to know that the patient has enough air to support respiration; and, indeed, the chloroform is usually given in such a manner that no knowledge is obtained, and no command exercised over the proportion of vapour in the air. This is certainly the state of matters when the chloroform is given on a handkerchief, or piece of lint; and I believe that the kind of inhaler used at St. Bartholomew's Hospital affords no means of either knowing or regulating, even approximately, the proportion of vapour in the air which the patient inhales. The chloroform may appear to be administered with it exactly in the same manner, when the process is, in fact, very different. So far, therefore, from having no hope that accidents from chloroform will be of less frequent occurrence, we have every reason to conclude that, with additional pains and attention, they may be almost, if not altogether, prevented.

Some persons direct their attention too exclusively to the pulse while giving chloroform. If the vapour were sufficiently diluted with air it would exert no great influence over the pulse, even if it were continued till the breathing should cease; and if it were not sufficiently diluted it might stop the pulse suddenly, without previous warning, when the information would come too late. The pulse is, therefore, but of secondary importance, as an indication of the effects of chloroform. The breathing, and the state of the eyes and eyelids, afford the best indication of the condition of a patient under chloroform; but there is no particular occasion for going into detail on this subject at present; for it does not appear that any accident has happened from the practitioner misunderstanding the state of the patient, and going on too long. The cause of accident has always been, that the vapour, being too strong, has acted so quickly, that there was not time to judge its effects.

While I do not participate in the melancholy forebodings of the writer who has reported the case in last week's Medical Times and Gazette, I cannot concur in the opinion of those who think that giving chloroform for a surgical operation is a very trifling matter, requiring no particular skill; and that it is merely necessary to spill a quantity of the agent on a towel or handkerchief, and make the patient quickly insensible. It is quite true, that this mode of proceeding answers in a great number of cases without any ill result; but it is attended all the time with some amount of risk, and the patients should be considered rather to escape from danger than not to incur any. In certain patients, the amount of chloroform which must be absorbed at one time, to prevent pain, and keep them from struggling during an operation, is not very far short of what would cause death; and, in nearly all cases, a larger [485/486] amount of chloroform must be used than would be fatal, if it were taken too quickly.

It is obvious, therefore, that the exhibition of chloroform in operations must always be a process of some delicacy, and requiring care. With due skill and attention, however, there is every reason to conclude that the danger from chloroform may either be altogether abolished, or reduced to an amount too small to be estimated.

All the chief organs were found to be in a healthy state in the patient who died in the Royal Infirmary of Edinburgh, as well as in the patient at St. Bartholomew's. In the case at University College Hospital there was fatty degeneration of the heart. This, however, is a very common affection; and many patients who have all the signs of it, as far as they are known, undergo the effects of chloroform without ill consequences. On reviewing the recorded cases of death from chloroform, now between thirty and forty in number, the patients appear to have possessed an amount of health and strength quite on average with the multitude who have taken chloroform in operations with the best results. Consequently, the condition of the patient has not been the chief cause of accident. It should still, however, be a matter of attention, not so much in order to prohibit the chloroform, as to use, if possible, additional care; for a patient with diseased heart, would undoubtedly have a less chance than others to recover from an overdose of chloroform, should he unfortunately be submitted to it. When a patient liable to syncope, with weak or intermitting pulse, and arcus senilis of the cornea, requires to undergo an operation of any consequence, there would probably be as much danger from the pain and mental disturbance accompanying it, as from chloroform carefully administered. In such cases, I take care to carry the effect of vapour no further, and to keep it up no longer, than is imperatively necessary; and if the operation, on account of its being about the mouth, require to be performed in the sitting posture, I have the patient placed horizontally immediately afterwards.

I am, etc.

18, Sackville-street, Oct. 31.

John Snow.

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