Physiological control of blood pumps using intrinsic pump parameters: A computer simulation study

Implantable flow and pressure sensors, used to control rotary blood pumps, are unreliable in the long term. It is, therefore, desirable to develop a physiological control system that depends only oil readily available measurements of the intrinsic pump parameters, such as measurements of the pump current, voltage, and speed (in revolutions per minute). A previously proposed Delta P control method of ventricular assist devices (VADs) requires the implantation of two pressure sensors to measure the pressure difference between the left ventricle and aorta. In this article, we propose a model-based method for estimating Delta P, which eliminates the need for implantable pressure sensors. The developed estimator consists of the extended Kalman filter in conjunction with the Golay-Savitzky filter. ne performance of the combined estimator-VAD controller system was evaluated in computer simulations for a broad range of physical activities and varying cardiac conditions. The results show that there was no appreciable performance degradation of the estimator-controller system compared to the case when Delta P is measured directly. The proposed approach effectively utilizes a VAD as both a pump and a differential pressure sensor, thus eliminating the need for dedicated implantable pressure and flow sensors. The simulation results show that different pump designs may not be equally effective at playing a dual role of a flow actuator and Delta P sensor.