Influence Analysis of Posture Change to Pulse Wave toward Continuous Cuffless Blood Pressure Estimation During Sleep

Abstract

The blood pressure variation (BPV) at night is closely related to the incidence of cardiovascular disease, and there is a compelling need for realization of continuous blood pressure monitoring without burden during sleep. In this study, for the purpose of estimating continuous BPV while sleeping, we focused on the influence due to the difference in (seating / supine) postures at the time of measurement. In the method of estimating the BPV from the form parameter of the photoplethysmograph, it is investigated how the difference in posture affects the pulse wave parameter and estimation accuracy. First, the effect of normalizing the pulse wave parameter to absorb the difference in posture was investigated by experiment. Next, by preparing a learning database for each posture, we constructed a dedicated estimation equation for each posture. Furthermore, we tried to estimate the BPV in sleeping period by using this supine posture learning database.