Open-loop analysis of circulatory system dynamics using artificial hearts

Two pneumatic artificial hearts were used to control separately the heart and peripheral circulatory system of awake animals and to acquire open-loop responses of the peripheral organ systems due to alterations in the pump output and oxygen consumption (dV/dt)O/sub 2/. The mixed venous hemoglobin oxygen saturation (S/sub v/O/sub 2/) varied nonlinearly with changes in the pump output with the dV/dtO/sub 2/ and (Hb) determining the slopes of the curves, while the S/sub v/O/sub 2/ varied linearly with changes in VO/sub 2/ with the slopes being determined by the product of pump output and hemoglobin content. In comparison to the normal heart animal where feedforward and feedback mechanisms are intact, the S/sub v/O/sub 2/ changes were enhanced.<>