Closed loop control of blood gases during surgical extracorporeal circulation

This study concerns the control of blood gases during extracorporeal circulation. The partial pressures of carbon dioxide and oxygen in the arterial blood can be controlled automatically by adjusting the total gas flow ventilating the artificial lung and its oxygen fraction. The hardware consisting of a continuous blood gas analyser, a controlled gas blender and an IBM PC is described together with the associated software. The experimental setup for the evaluation of the control strategy is outlined. We have designed a device to control the gas flow mixture during extracorporeal circulation (ECC). In order to keep blood gas values in a physiological range we propose to control oxygen and total gas flow rates during ECC. We present the device and the studies in progress.