Artificial anæsthesia and anæsthetics / by Henry M. Lyman.

  • Lyman, Henry M. (Henry Munson), 1835-1904.
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Artificial anæsthesia and anæsthetics / by Henry M. Lyman. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    Numerous experimenters have remarked the same thing in animals-which have been subjected to the action of opium and other narcotics. Anemic individuals have been observed to manifest greater intellecttial activity while occupying the recumbent position than in the erect—a circumstance which may be urged in favor of the anaemic hypothesis of sleep. Advan- tage of this fact has been taken in the construction of a rotating table for the induction of sleep in cases of persistent wakefulness that were supposed to be dependent upon cerebral hyperiBmia. Placing the patient in the recumbent position upon such a table, with his head nearest to the axis, when the apparatus is rotated, the blood is driven out of the brain by cen- trifugal repulsion, and is accumulated principally in the lower extremities. Sleep is said to result very promptly as a consequence of the cerebral anae- mia thus produced. The somnolence that sometimes accompanies the act of digestion has been ascribed to a diversion of blood from the brain to the gastro-intestinal capillaries. In like manner it has been suggested that the disposition to sleej) which is caused by an excessive atmospheric temperature is due to a general dilatation of the capillary net-work in the skin, producing a detention of blood at the periphery-, with a correspond- ing degree of anaemia in the internal organs. The good effects of warming the feet before retiring to bed, and the soporific influences of the tradi- tional dry ci-ust of bread when taken at the same hour, have been thus explained. It has been lU'ged, on the opposite side, that these hypotheses do not account for the excessive wakefulness which often accompanies the anaemic state. Nor do they seem to be consistent with the explanation ordinarily assigned to the cause of the contracted pupil which is constant during natural sleep. Dilatation of the pupil is the normal condition of that aperture in conditions of general anaemia. It is also a consequence of that irritation of the cei-vical sympathetic nerve Avhich produces contraction of the arteries of the head, and, presumably, diminishes the amount of blood conveyed to the brain. On the contrary, all those conditions which favor accumulation of blood in the brain, such as exist in asphyxia, or after sec- tion of the cervical sympathetic nerves, tend to produce contraction of the pupil. It is e^'ident, therefore, that if contraction of the pupil is to be as- sumed as a positive indication of intracranial hyperaemia, the brain must be the seat of increased blood-pressm'e during the time of sleep. But this inference is opposed by the experiments of Durham and others. It would appear, therefore, that we either have not in the eye an unvarying index of the state of the cerebral circulation, or that sleep may be associated with diflferent conditions of blood-supply in the brain. The highest degi'ee of probability, therefore, belongs to the hypothesis which undertakes to explain the phenomenon of sleep as the consequence of a certain stage of exhaustion of energy in nervous matter. It expresses the wear and tear of the intellectual apparatus. The machine can liberate motion for a certain length of time ; but at last its jiotential energy, derived from nutritive substances that have been introduced through the blood and have been incorporated by the cells, is entirely exhausted. Cessation of function must necessarily follow at once. Cessation of muscular function, occasioned by such exhaustion of the muscular ajoparatus, is muscular sleep. Cessation of the functions of the sensitive oi'gans of the body, oc- casioned in a similar manner, constitutes anaesthesia. Cessation of all the cerebral functions, thus induced, is natural sleep. That exhaustion of the materials furnished to the brain by the processes, of nutrition is an impor- tant cause of sleep is indicated by the increased power of resistance against