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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    9 vo for passage of water by osmosis from the blood, as suggested by | Henderson. Lastly, the fall of arterial pressure, owing to defective filling of the chambers of the heart, and the increased viscosity of the blood, will so reduce the rate of the coronary circulation as eventually to interfere with the nutrition and oxygenation of the heart-muscle itself. It will be seen, therefore, that when once the described con- dition is established, a series of ‘‘ vicious circles’ is set up. The determination of the change of plasma-volume from hemo- globinometer readings may be illustrated by an example. From a cat (under ether) an initial sample of arterial blood gave a hemo- globinometer reading of 80 p.c. When the profound shock produced by intravenous injection of 10 milligrams of the biphosphate of his- tamine (about 3 milligrams of the base) had fully developed—.e., about seven minutes after the injection—a second arterial sample gave a hemoglobinometer reading of 120 p.c. In order to translate these values into relative volumes of corpuscles and plasma, we must know the initial ratio of these volumes, and assume a constancy of hamo- globin content in the corpuscles. The hemotocrit showed that the corpuscles originally occupied one-third, and the plasma two-thirds of the blood-volume, which is a normal ratio for a cat. The rise of the hemoglobinometer reading from 80 to 120 p.c. must be taken to indicate an increase in the proportional volume of corpuscles in the same ratio. So that the percentage of corpuscles has risen from 33.3 to 33.38x 129 =50. If the volume of corpuscles has remained constant, this change of proportion indicates a fall of plasma-volume from 66.6 to 50 p.c. In other words, the plasma, which originally occupied twice as great a volume as the corpuscles, now occupies a volume equal to that of the corpuscles, so that one half of the plasma has disappeared from the circulation. A haematocrit deter- mination on the second sample actually showed the corpuscles and plasma occupying equal volumes, so that the assumption of a practi- cally constant hamoglobin content in the corpuscles was justified. The only means, other than the loss of one half of the plasma, by which such a change could be effected, would be a doubling of the number of red corpuscles in circulation, and it does not seem credible that this could occur in the course of a few minutes. It should be noted, further, that the arterial blood, on which the readings were made, represents a mixture of all the blood: reaching the heart from the different organs. Blood taken from the portal vein, when the shock-like condition has been produced, shows an even greater con centration than that from the arteries; and even this portal blood contains an undue proportion of blood from those of the capillaries in the splanchnic area in which the circulation is still relatively effec- tive. It must be supposed, that in many the vanishing arterial pressure is no longer able to maintain a circulation, so that the blood in them is stationary and its concentration extreme. Being impressed with the similarity of such a condition to surgical ‘* shock,’’ Dale and Laidlaw have made a short series of attempts to produce such a shock in anesthetised cats, by prolonged manipulation of the abdominal viscera, which, as Mann and others have pointed out, is the only method by which a traumatic shock can be produced in Carnivora. In two cases profound shock,. with no tendency to spontaneous recovery, was obtained, and in both these