Cardiac Output and Totl4l Peripheral Resistance in Post-hemorrhagic Hypotension and Shock1

The anesthetized dog when submitted to a prolonged period of drastic hypotension, achieved by controlled bleeding, enters into a state of irreversible shock. The standard procedure developed in this laboratory for producing this state (1) ent!ails lowering the arterial blood pressure by rapid bleeding to 50 mm. of Hg and sustaining it at this level for 90 minutes; it is then reduced to 30 mm. of Hg, at which level it is maintained for an additional 45 minutes. At the conclusion of this 135 minute interval of severe hypotension, all withdrawn blood is rapidly reinfused. Despite the latter procedure, verv fendogs have actually survived. Studies have also been conducted by members of this laboratory (2) to ascertain the nature of the permanent derangement produced by severe hemorrhagic hypotension. Ho th peripheral and cardiac events were followed during the development and terminal stages of the shock state. they used to measure cardiac output, though more satisfactory from many standpoints for th is purpose than gasometric methods, unfortunately necessitated the The cardiometric method which