Noninvasive Estimation of Blood Pressure Using Photoplethysmographic Signals in the Period Domain

In order to detect hypertension at its early stage, blood pressure (BP) of an individual must be carefully monitored. Aiming to monitor BP noninvasively and continuously, this study examines a new feature, normalized harmonic area (NHA), which is extracted from photoplethysmographic (PPG) signals in the period domain by using the discrete period transform (DPT). BP, pulse transit time (PTT), diastolic time (DT) and NHA were obtained from 28 subjects before and immediately after step-climbing exercise. It was found that NHA has more significant correlation with BP than PTT and DT in this study. The mean difference and standard deviation (mean plusmn SD) between the BP estimated from NHA and the reference BP obtained from a commercial oscillometric BP meter were 0.37plusmn4.3 mmHg and 0.51plusmn4.8 mmHg for SBP and DBP, respectively. The result indicate that NHA is potentially a useful indicator of arterial BP