“When animals are made to breathe air containing not more than four or five per cent. of the vapor of chloroform till death ensues, the breathing ceases very gradually, being first rendered laborious and then feeble, and the heart continues to beat for a minute or two after respiration has ceased. During this interval, while the heart is still beating, the animal can be easily restored by artificial respiration. This mode of death from chloroform might undoubtedly take place in the human subject, if a person were to go on giving it regardless of the symptoms; but a careful examination of all the recorded cases of death from this agent shows that it has not occurred in this manner. On the contrary, the symptoms of danger have in every instance come on suddenly, and the action of the heart has been arrested at the same moment as the breathing, or even before it. This is precisely the way in which the lower animals die when they are compelled to breathe air containing eight or ten per cent. of the vapor of chloroform. It is therefore evident that the cause of death is the inhalation of the vapor of chloroform not sufficiently diluted with common air.
“It requires more chloroform to suspend the functions of the ganglionic nerves, which preside over the contractions of the heart, than to suspend the functions of the medulla oblongata and the nerves of respiration; but the action of the heart may be arrested by the direct effect of this agent. Chloroform, when inhaled, is absorbed by the blood in the lungs, passes at once to the left cavities of the heart, and is immediately sent through the coronary arteries to every part of that organ, in less time, probably, than it can reach the brain; or, supposing the respiration to be suddenly arrested by the action of the chloroform on the brain, the vapor, not being sufficiently diluted, is present in large quantities in the lungs at the moment when the breathing ceases; and becoming absorbed, in addition to that which was already in the blood, has the effect of paralyzing the heart.
“Twenty-five minims of chloroform produce only twenty-six cubic inches of vapor, and as one hundred cubic inches of air, at 60° Fahr., will take up fourteen cubic inches of vapor, and at 70° will take up twenty-four cubic inches, if fully saturated, it is quite possible that the air during inhalation may contain ten per cent. of the vapor, if means be not taken to prevent it. Under these circumstances, each hundred cubic inches of air would contain nearly ten minims of chloroform, and this might be taken into the lungs at once by a rather deep inspiration. The average quantity of chloroform present in the blood of an adult, when sufficiently insensible for a surgical operation, is eighteen minims, while twenty-four minims are as much as can be present in the system at one time with safety. The absorption of a little more than thirty minims would have the effect of causing death, even if it were equally diffused throughout the circulation. It must be evident, therefore, that to take ten minims of chloroform into the lungs at one inspiration, when insensibility is almost complete, must be attended with danger.
“Robust persons, accustomed to hard work or violent exercise, are very apt to become affected with rigidity of the muscles and struggling, when nearly insensible from chloroform; and they often hold the breath for a time, and then draw a deep inspiration. It is under these circumstances that several of the accidents from chloroform have taken place, and extreme care is required to give the chloroform more than usually diluted with air, when this state of unconscious struggling and rigidity occurs.
“The most important point to attend to, in the exhibition of chloroform, is to insure that the vapor shall be sufficiently diluted with air during the whole process of inhalation. This may be effected with a suitable apparatus and proper attention, or if an inhaler be not at hand, the chloroform should be diluted with one or two parts by measure of rectified alcohol. One or two drachms of this may be placed on a hollow sponge, and repeated when required. The spirit has the effect of limiting the quantity of chloroform which rises in vapor, while very little of the diluent is inhaled, since, from its lower volatility, the greater part of it remains on the sponge or handkerchief employed to exhibit the chloroform.
“When the chloroform vapor is so diluted that it does not constitute more than four or five per cent. of the respired air, its effects become developed very gradually and regularly. The suspension of the sensibility of the conjunctiva at the border of the eyelids is the best sign that the patient will bear the operation without flinching, and the inhalation should immediately be left off if the breathing become stertorous. The pulse is not a very important guide in the exhibition of chloroform, for the two following reasons: 1st, if the vapor be sufficiently diluted with air, the pulse cannot be seriously affected by it; and 2d, if it be not so diluted, the pulse may cease suddenly, without previous warning of danger.
“If the vapor of chloroform be sufficiently diluted with air, it is practically impossible that any accident, really due to this agent, should occur. In case of accident, however, artificial respiration, very promptly and efficiently performed, is the only means which affords a prospect of restoring the patient—at all events, this is the only means found to restore animals when it was obvious they would not recover spontaneously. The prospect of success from artificial respiration will depend on the greater or less extent to which the heart is affected by the direct action of the chloroform.”
Mr. Syme, in his “Clinical Observations,” delivered in the Royal Infirmary in Edinburgh, recommends, in cases of approaching death from the use of chloroform, that the tongue should be drawn forward by means of a pair of artery forceps, by which it is presumed the epiglottis is raised, and a greater facility afforded for the admission of atmospheric air, the inconvenience resulting from two small holes in the tip of the tongue being amply compensated by the preservation of life.
Nevertheless, I am of opinion that attention should be paid to the pulse, and whenever it begins to fail or flutter, the inhalation of chloroform should be arrested; for respiration and the pulse often cease almost simultaneously, and in some instances have done so irrecoverably.
I formerly said that chloroform might be used with advantage in all cases of injury requiring amputation, save one, and in that one experience was wanting to decide the point. It is when a thigh has been carried off by a cannon-ball, or destroyed at its upper part by any other means, such as the wheels of a railway carriage or other weighty machine. When the thigh is carried off by a cannon-shot, the artery being torn across, there is so great a shock and so great a loss of blood at the moment, followed by fainting, or such faintness as leads to the belief that the sufferer is dying, and some do actually die without an effort at recovery. In such a case, or in one somewhat similar, Dr. Snow and others think chloroform would act as a stimulus, and that it would enable the patient to bear the operation of amputation with success, which he otherwise might not have done. It may be so; but, as I believe nothing in surgery until fairly tried and found to answer, I refrain, for the present, from expressing a positive opinion, save that the trials should be made with great caution, inasmuch as the observations which have been made in the Crimea have not been sufficiently numerous or so decisive as to settle the point in favor of the chloroform, although they confirm all the others to which allusion has been made. In these cases a tourniquet cannot be applied, and the sudden loss of blood saves the life of the sufferer for the time, by suppressing the bleeding; which suppression, I have long since pointed out, is effected in the artery at the groin, by the formation of a coagulum, and not by the contraction and retraction of the vessel into the shape of the neck of a claret bottle, which would take place at the lower third of the same artery in the thigh under a similar injury; in which case, also, the bleeding would cease by the unassisted efforts of nature. If the artery, there or elsewhere, should, on the contrary, be only partially divided, the person would bleed to death, unless surgery of some kind should come to his aid.