THE CIRCULATORY EFFECTS OF ACUTE EXPERIMENTAL HYPERVOLEMIA

Abstract

The plasma and erythrocyte volumes of anesthetized dogs were increased experimentally by slow infusion of sedimented corpuscles. Pressure changes in the veins, ventricles and central arteries were followed by the use of calibrated optical manometers; alterations in urinary secretion, splenic volume, intra-thoracic pressure and heart rate were also recorded. The maximum capacity of the various blood reservoirs of the body was inadequate to prevent an increased venous return to the heart during polycythemic hypervolemia. The systolic discharge of the left ventricle increased as shown by the larger pulse pressure, the increases in the phases of isometric contraction and systolic ejection and by the increased initial tension in the ventricles. During the early stages of polycythemic hypervolemia the increased arterial pressure was caused mainly by the augmented systolic discharge; later, when the polycythemic hypervolemia became extreme an increased peripheral resistance undoubtedly played a role as shown by changes in the pressure pulses and by a slower gradient of diastolic decline.