Cardiovascular Responses to Induced Hypervolemia

Abstract

A fear of hypervolemia and the lack of adequate clinical guides to proper volume replacement can lead to inadequate blood replcement and poor tissue perfusion. To evaluate hemodynamic changes associated with overtransfusion and to correlate measurements used clinically with changing blood volumes, blood volume was doubled in 50 mongrel dogs over a period of 50 min. Blood was given in increments of 10% every 15 min. and volume was monitored with albumin I131. Right atrial, pulmonary arterial, left atrial, aortic and portal venous pressures were monitored and serial measurements of cardiac output, pH, pO2 [O2 tension], pCO2 [CO2 tension], serum K, hematocrit and urine flow were made. Response to hypervolemia consisted of increasing cardiac output, arterial and portal venous pressures. Pulmonary and peripheral vascular resistances decreased. Atrial pressures did not change significantly and did not reflect massive increases in blood volume. Their value lay in reflecting ventricular function. Results of these experiments as they apply to improved volume management in clinical situations are discussed.