Automatic systems for maintaining the venous reservoir level of an opened-fashion and a closed-fashion cardiopulmonary bypass circuit

Abstract

We designed and examined venous reservoir level automatically controlling systems for an open-fashion cardiopulmonary bypass(CPB)circuit(an open circuit level controller; OLC)and a closed-fashion CPB circuit(closed circuit level controller; CLC). The OLC system consists of a CPU(central processing unit)and a slender column inserted through the top of the venous reservoir for measuring hydrostatic pressure. The CPU analyzes the hydrostatic pressure in the column as a replacement for the venous blood level and regulates the blood pump speed in proportion to the change of the hydrostatic pressure. The CLC system consists of a commercially available level sensor, which is attached in the side wall of the venous reservoir for directly measuring the venous blood level, and a CPU regulating the blood pump speed for keeping the appropriate venous blood level.
Using a mock circulation model, we confirmed the both systems could maintain an appropriate blood level in the venous reservoir and regulate blood pump speed, leading to guarantee easy and safe management of the cardiopulmonary bypass.