Indirect measurement technique for a portable artificial heart drive system

Monitoring of blood pressures is essential to the physiological control of the blood circulatory system when artificial hearts are used. Efforts to obtain long term, reliable direct measurements of blood pressures have not been successful because of blood clotting impairing the function of sensors, baseline drift, artifacts on measurements, and health hazard-related catheterization. This paper is concerned with an on-line estimation technique of blood pressures for a portable artificial heart drive system. The technique is based on measurements made for the drive system outside of the body and on mathematical models of the drive system components. The test of the on-line estimation technique with a mock circulatory loop showed successful correlations between the actual values and their optimal estimates. The developed approach offers the following advantages: elimination of blood clotting problems, accessibility to the pressure transducer for recalibration, and noninvasive location of the transducers.