On narcotism by the inhalation of vapours. Parts XVII and XVIII / by John Snow.

  • John Snow
Date:
1852
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Licence: Public Domain Mark

Credit: On narcotism by the inhalation of vapours. Parts XVII and XVIII / by John Snow. Source: Wellcome Collection.

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    KtHlTABiLn Y OF TIIF, MtJSOI.I' S aFi KR DEATH. flows from a wound, so long as the in- halation is not pushed to the extent of enihamissing the respiration, and pro- vided the patient is not holding his breath, on account of tlio pinigonoy of the vapour, or a general stale of rigidity which sonietinu'S occurs for a minute or two; out when the hlood wiiich flows from the arteries and veins can be separately observed, whilst tlie pa- tient is well inidor the influence of the narcotic, it is seen that the arterial blood is somewhat less florid, and the venous blood less dari; than uiuler ordi- nary circumstances. The lighter colour of the venous blood, which lias been spoken of by 13r Gull, as well as by myself, points j^articularly to a diminu lion of oxidation in tiie systemic capil- laries. The phenomena attending the irrita- bility whicli remains in the muscles for a longer or shorter time after death, and particulaily tiie effect of narcotics on this irritability, accord exactly with the views above expressed. It can be shown, by the following amongst other reasons, that the muscvflar irritability depends on a little oxygen still remain- ing in the blood contained in the mus- cular tissue. Nysten* found that the injection of oxygen gas into the cavities of the heart increased the vigour and duration of the contractions.. Sir B. Brodie states that, in dogs in which the circulation was kept up after death by artificial respiration, tliere seemed to be actually an increased irritability of the voluntary muscles, continued not for a short time, but even for an hour and a half'f Nysten informs us]; that the general result of his observations on the duration of the muscular irritability in animals of diflerent classes, and of different orders of the same class, was in the inverse ratio of the muscular energy develo])ed during life; and we previously saw, on the authority of Edwards, that this was just the ratio of duration of life under privation of air or asphyxia. Cliloroform, ether, alcohol, and pro- bably all narcotics, have the power of suspending the nuiscular irritability. In a former paper of tliis series^ some experiments were related in which the ii-ritability of tlie heart in frogs and * RpcheiThes Pliysiologiques,' p. 335. t Physiological Ucseiirchcs, ISSI, p. 108. Opus cit. p. 355. § Vol. xlii. p. 415, 614. rabbits was removed by the vapour of chloroform ; and in two of the exjjeii- ments the irritahility was alternately allowed to recover by letting the chlo- roform evaporate, and then suspended again by a I'rosh exposure to tiie vfli)our. In one of these ex])erim('nts the peris- taltic action of the small intestine of a rabbit was arrested by the local action of chlorolbrm. I have l're(piently stopped the quivering motion of tiic intercostal muscles, which is seen on o|)ening the chest of an animal imme- diately after death, by blowing a little vapour of chloroform on them through a tube. On one of these occasions Dr. Sihson was present. The following experiments show the action of chloroform, &c., on all the muscles of the body :— Exp. 80.—A half-grown guinea-pig was made to inhale chloroform in a glass jar till it ceased to breathe. The chest was then opened, and a tube armed with a stop-cock was introduced into the aorta and tied. The heart was still contracting, and the muscles were very sensible to the shocks of an electro- magnetic apparatus. Fifteen minims of chloroform, and two drachms of tepid water, which had been agitated together till the chloroform was suspeneed in minutes globules, were now injected. At the moment of injection the right anterior extremity and the two posterior extremities were stretched out, and the toes quivered. These limbs became quite rigid at the moment of the injec- tion, as did also the neck and trunk of the animal. The left anterior extremity remained flexible. The wires of the battery were applied to the muscles of .various parts of the body immediately after the injection, but no contractions could be e.xcited, except in the left ante- rior extremity, and the muscles of the cliest on the same side, wliich remained as irritable as before; the reason of this being that the injection had not entered the left subclavian artery. The heart ceased to act at the moment of the injection, and was afterwards quite in- sensible to the shocks of the battery. Exp. 81.—A similar guinea-pig to the last was killed by the inhalation of ether, and was opened immediately after it. ceased to breathe, whilst the heart was still acting. The tube was secured in tlio descenduig aorta, and two fluid drachms of sulphuric ether were injected. The posterior extremities were stretched