Abstract
Summary
The effects of changes in blood volume by blood transfusion and hemorrhage on the cardiovascular dynamics were studied in dogs with a large A-V fistula. It was found that the increased blood volume by continuous blood transfusion progressively increased mean systemic arterial pressure, pulmonary arterial pressure, left and right atrial pressures, total cardiac output and systemic blood flow, and decreased heart rate, and systemic and pulmonary peripheral resistances. In contrast, the decreased blood volume by hemorrhage increased heart rate, and total, systemic and pulmonary peripheral resistances, and decreased systemic, and pulmonary arterial pressures and left and right atrial pressures. In either instance, the magnitude of the changes in A-V fistula flow was markedly smaller than that in total cardiac output and systemic blood flow. It is concluded that the magnitude of A-V fistula flow is not modified directly by the blood volume or systemic blood flow, but mainly by the A-V pressure gradient across a given A-V fistula if the blood viscosity remains unchanged.
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