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A Physiological Model-Based Study of Flow-Mediated Dilation in Peripheral Arteries Using Finger Photoplethysmogram Signal

Flow-mediated dilation measurement in the brachial artery using ultrasound imaging (FMD-US) is a common noninvasive procedure for endothelial function evaluation in the peripheral arteries. As FMD-US is operator-dependent and involves onerous equipment, its use has been mostly confined to research settings. In this paper, we propose to use the more accessible finger photoplethysmogram signal in conjunction with the FMD test (FMD-PPG) as a surrogate method. To this end, a tube-load physiological model of the upper arterial path in the arm is developed. Signals acquired from young and elderly subjects (N=20) are then investigated using model parameter estimation by the genetic algorithm. Our results show that the estimated parameter values for the elderly group in baseline are significantly different from that in the young group (p<0.05), and the parameter changes in cuff release interval are consistent with existing literature. Therefore, the presented FMD-PPG may hold a great potential in non-invasively assessing the endothelial function.