STUDY OF ADAPTIVE PRESSURE ESTIMATION
Yi Wu, Paul E. Allaire, Don B. Olsen · ASAIO Journal · 2006
Purpose of study. The effective control of blood pressure is critical for the physiological control of a left ventricular assist device (LVAD). This work is to study the estimation error of an adaptive estimation algorithm in the presence of variations of total peripheral resistance, heart variables, and aortic capacitance. Methods used. A linear state space model is derived to approximate the response of human circulatory system with LVAD support. Based on this model, an adaptive algorithm has been developed to estimate the average aortic pressure. Different scenarios are simulated in Matlab and mock circulatory loop to test the performance of the adaptive algorithm. Summarize results. The adaptive estimator tracks the aortic pressure in the presence of large variation of total peripheral resistance within a couple of mmHg. The estimation error (True aortic pressure - estimated aortic pressure) is positively correlated with heart rate, but negatively correlated with the pulsation of flow, the systole vs. diastole ratio, the ratio of left ventricular flow to total flow (illustrated in Fig. 1), and the compliance of aorta. Result of this study can be utilized for the control of long term LVAD, or used for non-invasive evaluation of left ventricular function and aortic compliance.Figure