AN ACTIVE NON-INTRUSIVE SYSTEM IDENTIFICATION APPROACH FOR CARDIOVASCULAR HEALTH MONITORING

Abstract

In this study a novel active non-intrusive system identification paradigm is developed for the purpose of cardiovascular health monitoring. The proposed approach seeks to utilize a collocated actuator sensor unit devised from the common blood pressure cuff to simultaneously 1) produce rich transmural blood pressure waves that propagate through the cardiovascular system and 2) to make measurements of these rich peripheral transmural blood pressures utilizing the pressure oscillations produced within the cuffs bladder in order to reproduce the central aortic blood pressure accurately. To achieve this end a mathematical model of the cardiovascular system is developed to model the wave propagation dynamics of the external (excitation applied by the cuff) and internal (excitation produced by the heart) blood pressure waveforms through the cardiovascular system. Next a system identification protocol is developed in which rich transmural blood pressures are recorded and used to identify the parameters characterizing the model. The peripheral blood pressures are used in tandem with the characterized model to reconstruct the central aortic blood pressure waveform. The results of this study indicate the developed protocol can reliably and accurately reproduced the central aortic blood pressure and that it can outperform its intrusive passive counterpart (the Individualized Transfer Function methodology). The root-mean-square error in waveform reproduction, pulse pressure error and systolic pressure errors were evaluated to be 3.31 mmHg, 1.36 mmHg and 0.06 mmHg respectively for the active nonintrusive methodology while for the passive intrusive counterpart the same errors were evaluated to be 4.12 mmHg, 1.59 mmHg and 2.67 mmHg indicating the superiority of the proposed approach.