Figure 1: Extracorporeal bypass circuit.
Blood drained (by gravity) into the open venous reservoir. Blood exiting the reservoir was pumped either through a polypropylene membrane oxygenator by the systemic roller pump (P1) back into the animal or diverted by a second roller pump (P2) to create an air: blood interface shunt that was recirculated back to the venous reservoir. The air- blood interface was controlled by a Hoffmann clamp to expose the blood to a negative pressure of 100 mmHg. A pressure relief valve opened to introduce air into the shunt at −100 mmHg.