A Servo-Controlled, Whole Body, Blood Perfusion System as a Pressure/Flow Clamp

To study the peripheral vascular system of anesthetized dogs, a whole body, blood perfusion system was developed to provide 1) a nonpulsatile output of 2) constant pressure (0-300 mm Hg), or 3) constant flow (0-3 liters/minute), or 4) any output characteristic between these extremes, and 5) the output controllable from a voltage command signal. Output is determined by pneumatic pressure, adjusted by a servo valve from the error signal, which drives the blood from a reservoir into the animal's aorta. The error signal is derived from the difference between either a flowmeter or pressure-gage signal and an adjustable set-point voltage, or any combination of these signals. Response time is less than 1 sec. Heat and gas exchange are provided by a double-walled disk oxygenator. Plasma hemoglobin accumulation is typically 0.2 mg/ml hour.