Adjustments of the Circulatory System Following Very Rapid Transfusion or Hemorrhage

Abstract

Massive transfusions and hemorrhages were performed in less than 1 min., and the readjustments of the circulation were studied. Following transfusion the arterial and venous pressures rose immediately but returned toward the normal control level of pressure along an exponential curve with a half time of approx. 110 sec. Fluid and protein, amounting almost exactly to the plasma proportion of the transfused blood, was lost from the circulation at approx. the same rate as the rate of readjustments in pressure. Furthermore, the readjustments occurred even though vasomotor control was anesthetized. In animals with excessive sympathetic activity, the readjustment level of blood pressure after transfusion was always high, whereas decreased sympathetic activity was always associated with low readjustment pressures. It is concluded, therefore, that the level of blood pressure is almost entirely a function of sympathetic activity and only to a slight degree a function of blood quantity available as long as at least a sufficient amount is in the circulation. In the hemorrhage expts., readjustments were only partial, and these appeared to be almost entirely nervous in operation, for no evidence of rapid fluid shift with readjustment of blood volume could be found.