On chloroform and other anæsthetics: their action and administration

by John Snow

The same quantity of amylene was employed, and the kitten was introduced again, and allowed to remain for fifty seconds. On its first removal the heart was not beating, but the kitten was gasping; and just afterwards the heart was heard to be beating rapidly. The kitten quickly recovered.

One hundred and twenty grains of amylene were allowed to evaporate in the jar, and the kitten was introduced again. It was allowed to remain a minute, and was taken out as the breathing appeared to be on the point of ceasing. The heart was beating when the stethoscope was employed, and the kitten quickly recovered. It seemed impossible to kill it with amylene, except by allowing it to remain and inhale the vapour, by those gasping inspirations which took place when the action of the heart was arrested, and which restored the action of this organ, when the kitten was withdrawn from the vapour. In the different parts of this experiment there were 37, 42, and 47 per cent. of amylene in the air.

When mice are placed in air containing 30 per cent. and upwards of vapour of amylene, they usually recover, as in the following experiment, if the breathing has not entirely ceased on their removal; whilst if they are placed for a quarter of a minute in air containing 8 or 10 per cent. of vapour of chloroform, they generally die, although they may be breathing well, and hardly insensible, when they are removed.

Experiment 53. Eighty grains of amylene were introduced into a jar holding 330 cubic inches, and when it had evaporated, a white mouse was introduced. In about five seconds it was quite insensible, and in about a quarter of a minute the breathing appeared to have ceased. The mouse was quickly withdrawn, and immediately began to gasp. After a few gasps the quick breathing returned. In half a minute after its removal the mouse was recovering, and it was soon quite well. There was 32 per cent. of vapour of amylene in the air in this experiment.

I administered amylene with the inhaler which I had used for several years in exhibiting chloroform, and which I have described in treating of that agent. In administering chloroform it is desirable that the patient should breathe 4 or 5 per cent. of the vapour in the air he inspires; and the air, when saturated with vapour of chloroform at 60°, contains 12 per cent., or nearly three times as much as the patient ever requires. In administering amylene for surgical operations, it is desirable that the patient should take in 15 per cent. of the vapour with the air he breathes; and air, when saturated with this vapour at 60°, contains 465. per cent., or fully three times as much as the patient ever requires. It therefore seemed reasonable that the inhaler which had answered so well with the former agent, might be employed in the same manner, and used successfully with the latter agent. Vapour of chloroform, when inhaled of twice the proper strength, i. e., of 8 or 10 per cent., is capable of causing sudden death by over-narcotism of the heart; but amylene is required to be of nearly 40 per cent., or more than twice the proper strength, before it could produce this result: and it seemed, therefore, reasonable to expect that the inhaler which had been employed for so many years with chloroform, might be employed in exhibiting amylene with an equally satisfactory result. And if the amylene furnished for inhalation had been a constant and uniform product, boiling steadily at the same temperature, like chloroform, there is no doubt that these expectations would have been fulfilled.

I first administered amylene, in King’s College Hospital, on the 10th of November 1856, to two boys, about fourteen years old, previous to Mr. Samuel Cartwright extracting some teeth. I had but a few drachms, and being very sparing of its use, it did not entirely remove consciousness in either case, and the pain was not altogether prevented: the effects, however, as far as they extended, were so favourable as to encourage a further trial, which was made in the same institution, on December 4.

On this occasion I exhibited the amylene to four patients—two men, a young woman, and a girl of ten years old: it occasioned complete unconsciousness and absence of pain in each case. The first man was about thirty-five years of age. Half a fluid ounce of amylene was put into the inhaler, and he inhaled for three minutes. At first the valve of the face-piece was about one-third open, but it was gradually moved till it was almost closed. The man breathed readily, without coughing, and in a very little time seemed to be unconscious. The pulse became quick and slightly irregular; the skin became flushed; and in about two minutes there was a rather free sweating of the forehead; the eyes did not turn upwards; the conjunctivæ did not become insensible; there was no relaxation of the limbs, and, on the contrary, no struggling. The patient sat well, supporting himself, without any tendency to slide out of the chair; the mouth was partly open, and there was a tendency to laugh, just as the amylene was discontinued. The tooth was extracted by Mr. S. Cartwright, without making him flinch or cry in the least. In less than a minute he awoke. He looked a little strange at first, but immediately remembered all the circumstances of his situation, but knew nothing of the operation; and, three minutes after the extraction of the tooth, and six minutes after entering the room, he went away feeling, as he said, quite well. The amylene put into the inhaler was nearly used.

A young man, about twenty years old, next inhaled the same quantity, in exactly the same manner, for just three minutes; there was no irregularity of pulse, and no sweating; otherwise the symptoms were exactly the same. The tooth was extracted without his knowledge, and without causing a cry or flinch. He awoke, and was able to go in three minutes.

A young woman in bad health, an out-patient of one of the physicians of the hospital, next inhaled. She breathed the amylene for four minutes, and about three drachms were used. The effect was carried to the commencement of the third degree of narcotism; and the eyes were inclined to turn up, but did not do so persistently. The edges of the eyelids also remained sensible. There was a little trouble and delay in getting the mouth open, as the muscles of the jaws were rather rigid; and when the tooth was extracted, she flinched, and cried out a little. She did not remember the operation. She said she had had a very unpleasant dream, and she was dizzy and uncomfortable for about ten minutes, after which she was better.

A little girl ten years old inhaled for four minutes, and between two and three drachms were used. The eyes were turned up for a short time. She did not flinch or cry as the first tooth came out, but did both as two others were afterwards extracted. She did not, however, know anything afterwards of the operation. She recovered her consciousness in a minute or two, and quite recovered from the effects of the vapour in a few more minutes. There was no sickness, and no increased flow of saliva, in any of the cases.