Amylene differs widely from chloroform, and still more from sulphuric ether, in the promptitude with which patients generally recover from its effects. This is a character of amylene which might have been predicted from its physical properties. I have many times observed how quickly, and, indeed, almost instantaneously, small animals recover from the stupor occasioned by certain permanent gases which are sparingly soluble in watery fluids, as olefiant gas, carbonic oxide and carbonic acid gases, nitrous oxide and the gaseous oxide of methyle. Now amylene is so volatile as to approach to a permanent gas; at a temperature a little above that of the human body it would be a gas, and the vapour is very sparingly soluble in watery fluids, and consequently in the blood. Sulphuric ether is, indeed, as volatile as amylene. I cannot remember any other two bodies whose volatility is so nearly alike; but sulphuric ether is very soluble in watery fluids, in comparison with amylene. Water dissolves a tenth of its volume of liquid ether, or 23 volumes of the vapour. Consequently a large quantity of ether is absorbed during inhalation, and the blood has to pass many times through the lungs before it is freed from it. The quantity of amylene which is absorbed is, on the contrary, extremely small, as I have explained above, and this, together with its volatility, is no doubt the reason why the patient recovers so promptly from its influence. In about a minute after the operation is concluded, and the inhalation left off, the patient usually awakes from the influence of amylene, and completely recovers his consciousness. The same quick recovery may take place after chloroform, but more frequently it is a few minutes before the patient is quite conscious. I have seen two or three instances in which a child has slept for twenty minutes or half an hour after amylene, but it must be remembered that children sometimes sleep for hours after chloroform in cases where the operation has not produced a painful wound. The quick recovery of the patient is a decided advantage in all minor operations. In great operations, where the patient is obliged to keep his bed afterwards, it is of less consequence whether he wakes promptly or not, although, even under these circumstances, his friends are generally anxious to see him recover his consciousness. The smarting of the wound after an operation is often prevented longer when chloroform has been employed than after the use of amylene, and this may be considered as a slight advantage which chloroform possesses in certain cases. In some instances, however, in which chloroform has been used, the patient begins to show symptoms of suffering pain in the wound before he has entirely recovered his consciousness, while after amylene I have not seen symptoms of pain in the wound till consciousness had completely returned. In any cases where the pain after an operation, either from a wound or ligatures or caustic, is very great, the inhalation of the agent which has been employed may be gently repeated at times until the pain has a tendency to subside, or till an opiate shall take effect.
The patient generally seems surprised or confused on first recovering from the effects of the amylene, but in a few seconds he becomes, in most cases, completely conscious of his position, and feels that his mind has been wandering. He often says he does not know where he has been in his dreams, or that he has been a long way. Sometimes he does not remember exactly what he has dreamed about; at other times he does. All this is common enough after chloroform, except that the process of recovery is generally much slower; but there is one condition of mind which is very common after chloroform, which I have rarely met after amylene, I allude to that condition in which the patient asserts that the vapour has not taken effect, and that he has not been asleep at all.
Amylene appears to support the pulse under loss of blood at least as well as chloroform. I have not found the pulse to fail, although there was rather free hæmorrhage in some of the operations.
There has been a little headache in a few of the cases as the effects of this agent were subsiding, but it passed off in a few minutes.
In administering amylene, the vapour must be given of such a strength as will cause insensibility in about three minutes, or it will not succeed at all unless the strength of the vapour be altered. In giving chloroform, the vapour may be of less than half the desirable strength, and by continuing more than twice the usual time, the patient may be rendered insensible; and in using sulphuric ether, the vapour may be breathed of one-seventh the proper strength, and by continuing it constantly for seven times the usual period, i. e., for half an hour, the patient might be rendered insensible; but in using amylene, time will not make up for deficiency in the strength of the vapour. If the vapour be not strong enough to cause insensibility in about three minutes, it might be breathed for an indefinite period without causing insensibility; and the patient is solely affected by what he has inhaled within two or three minutes.
On account of the very rapid subsidence of the effects of amylene, it requires to be very frequently repeated during the performance of an operation. The patient generally requires to inhale a little of it every half minute or so to keep up its effect. On this account, it is not well adapted for certain operations on the face. I did, however, administer it with complete success in several operations on the face in King’s College Hospital. Amongst these, there were four operations by Mr. Fergusson for making a new nose in which I administered amylene, and succeeded in preventing the pain by holding a hollow sponge, wetted with that agent frequently, near the mouth and nose.
In cases of tooth-drawing, in which a number of teeth or stumps have to be taken out, the effects of the amylene are apt to pass off before the operation is completed, and the inhalation has to be repeated once or twice, but in cases when only one or two teeth require to be extracted, amylene has a great advantage in the promptitude with which the patient recovers from its effects. There is occasionally some difficulty in opening the mouth with amylene, as with chloroform.
The patient has nearly always a very cheerful expression of countenance when he recovers from the amylene, and the state of his mind, as indicated by his conversation, corresponds to his look. Dr. Debout has noticed the same circumstances. Speaking of the patients operated on under amylene in Paris, he says, “A leur réveil et le premier moment de stupeur passé, leur physionomie est épanouie.” The same state of countenance and mind is met with after chloroform only now and then, and is by no means the rule.
Hysterical symptoms occurred in a few women after operations under amylene. They were met with about as frequently, I think, as after chloroform. These symptoms generally subsided in a few minutes; but in one or two young women in the hospital, they lasted nearly an hour.
The greatest advantage that amylene possesses over ether and chloroform, is the great infrequency with which it excites sickness. I only saw vomiting occur in two of the 238 cases in which I administered amylene, although it occurred before I left the patients’ room in twenty-two cases out of 100 in which I administered chloroform and kept an account of this symptom, at the time I was using amylene. In the greater number of the cases in which chloroform was exhibited, the patients had been requested not to take a meal; whilst in the cases in which amylene was administered, no directions regarding diet had as a general rule been given.