Controller design for extracorporeal life support

An automatic controller for extracorporeal life support (ECLS) was designed and tested in vivo. The design goal was to improve upon manually-operated ECLS by automatically adjusting system parameters to meet oxygen (O/sub 2/) delivery and carbon dioxide (CO/sub 2/) removal needs of the patient, while monitoring system performance to enhance safety. The patient/ECLS System was modeled by two first order systems with a time delay representing transit times for blood moving between the patient and blood gas sensors. One proportional-plus-integral controller adjusted blood flow based on venous O/sub 2/ content, and another varied gas flow through the gas exchanger based on venous PCO/sub 2/ measurements. Tuning of controllers was based on open loop step response. The controller was successfully implemented and validated in a sheep model. This controller would minimize the duration of support (thereby reducing cost and invasiveness of the procedure), as the patient would be weaned from support as cardiopulmonary function improved.