Abstract
The Takagi's automatically air-driven blood pump was modified to prevent air embolism in a case of the rupture of blood chambers. The modified pump consisted of a blood, a saline, and an air chamber. The sack type blood chamber was placed in the acrylic cylinder filled with sterilized saline solution. The blood chamber was compressed and expanded indirectly by the diaphragm which separated the saline and the air chamber and moved with compressed air. An electro-air regulator was used instead of a stepping motor to simplify the regulating unit. On a mock circulation, the pump with 6ml blood chambers for neonates produced 600ml/min of flow and one with 20ml blood chambers for children did 900ml/min of flow. The modified pump was actuated under automatic control to change air pressure, pumping rates and pump flow in response to the preload and the afterload. It responded smoothly without any delay or decrease. It ran without mechanical problems for 21 days without an oxygenator and for 10 days with an oxygenator. Results obtained on animal experiments also confirmed the reliability and safety of our new ECMO system which could successfully bypass at the flow rate over 100ml/kg/min.
