A hydrostatic calibration method for the design of wearable PAT-based blood pressure monitoring devices

Pulse arrival time (PAT) has been proposed for measuring blood pressure (BP) noninvasively and continuously. A challenge of the PAT-based BP measurement technique is to calibrate it individually. The objective of this study is to examine a previously proposed model-based calibration method utilizing hydrostatic pressure for BP estimation. A preliminary experiment has been conducted on eight subjects aged from 23 to 36. Each subject was asked to raise their right arms to five different heights (H). At each height, PAT and brachial BP were measured from the elevated arm and the resting arm respectively. The data recorded at each height were used to calibrate a subject-dependent coefficient b which was then used to estimate his/her brachial SBP before and after exercise. It was found that the estimation results were influenced by H and k, which is a constant time interval subtracted from PAT. In this study, the estimation errors were found to be more sensitive to H than to k for -30< or =H< or =30 cm and 40< or =k< or =70 ms.