EXPERIMENTAL TRAUMATIC SHOCK PRODUCED BY MUSCLE CONTUSION WITH A NOTE ON THE EFFECTS OF BULLET WOUNDS. A STUDY OF THE CLINICAL SIGNS OF SHOCK IN THE DOG AND OF THE RÔLE OF BLOOD VOLUME REDUCTION IN THE DEVELOPMENT OF THE SHOCK SYNDROME

Abstract

The clinical signs shown by dogs in which the thigh muscles have been contused are identical with those which in man constitute the syndrome of secondary shock. These consist of increased heart rate, decreased body temp., various signs of vasoconstriction, changes in respiration and evidence of central nervous depression. As in human subjects, dogs in shock do not shiver even though the body temp. may be depressed several degrees. In both spp. thirst is present and ingested fluid is usually vomited. In the dog it has been possible to reproduce all of the signs of clinical shock with the exception of sweating. The physiologic signs which in man are recognized as characteristic of traumatic shock can be reproduced experimentally in the dog by gunshot wounds. Muscle trauma and shock do not fundamentally alter the validity of the dye dilution method for the measurement of plasma volume. Muscle trauma which is severe enough to reduce the blood vol. by 30% or more invariably produces shock, and the shock is usually fatal. Fatal shock sometimes occurs when the decrease in blood vol. is less than 30%. The blood vol. is reduced at, or shortly after, injury and remains unchanged for several hrs. After injury the hematocrit values are usually greater (except in splenecto-mized dogs) than during the control period, but they are maintained at the new levels with little change for several hrs. The plasma protein concn. may increase or decrease slightly. As in the case of the hematocrit reading the new level remains relatively constant for some time. The relation of these results to the problem of capillary leakage is discussed.