Memorandum upon surgical schock and some allied conditions.

Date:
1917
Catalogue details

Licence: Public Domain Mark

Credit: Memorandum upon surgical schock and some allied conditions. Source: Wellcome Collection.

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    found fall of blood-pressure produced by this substance is accompanied by a striking concentration of the blood, amounting in some cases to a loss of one-half the original volume of plasma in about five minutes. The liver appears to be the organ most actively concerned in this reduction of the plasma-volume; but it is not exclusively responsible, for the phenomenon occurs, though less regularly, when the drug is injected after exclusion of all the abdominal viscera. The concentration is apparently effected not merely by loss of water and diffusible constituents, but by the passage into the tissues and lymph-spaces of all the plasma-constituents, since the protein content of the plasma does not rise in proportion to the reduction of volume. If an animal, moribund from this type of shock, is opened, it is found that the heart is executing muscular beats of moderate vigour, although the arteries are pulseless. The veins are not distended and the great veins fill only very slowly from the periphery if clamped. A large part of the blood, in fact, has disappeared from effective circulation, and the weakness of the heart-beat is due to defective inflow from the veins. | ¢ The condition cannot wholly be explained by the loss of plasma- volume above described, for Dale and Laidlaw have several cases on record in which the drug produced a ‘‘ shock ’’ of some severity, with the general signs of oligamia as above described, but with no loss of plasma, as measured by concentration of corpuscles, or a loss so small as to be quite inadequate to explain the effect. They further regard a loss of tone of the smaller arteries as insufficient to account for the extreme circulatory depression (the still incomplete evidence points rather to these being constricted in these circum- stances), and provisionally attribute the shock in the first instance to a widening of the whole capilary area in the viscera and the muscu- lature. The active contractility of the capillaries has been frequently described, and important evidence of its existence in man has just been provided by Cotton, Slade and Lewis (Heart 1917). Dale and Laidlaw suppose that, under the action of the poison, the capilary tone is lost, so that, the blood from the arterioles being diffused and stagnant among the slack capillary channels, the quantity of blood reaching the veins is inadequate for the filling of the heart. The cardiac output falls in consequence to a very low level An attempt will be made to test by direct experiment this hypothesis of circulatory stagnation as the result of general loss of tone of the capillaries. About the main fact—that there is a deple- tion of the macroscopic vessels both on the arterial and venous sides —there can be no room for doubt; and it will be obvious how this deficiency of blood-volume, relative to the total capacity of the system, will be aggravated by the direct reduction of the blood- volume, owing to loss of plasma into the tissue spaces which usually accompanies it. The already sluggish circulation will be further impeded by the increase of the viscosity of the blood, mainly due to the increase in the proportion of corpuscles to plasma. This change of viscosity has been directly observed by Trevan (vide infra). The slowness of the capillary circulation, again, through the muscles and other tissues needing a plentiful supply of oxygen, will lead to defec- tive oxidation, with resulting acidity, and so to a further tendency
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