Cuffless blood pressure estimation using only photoplethysmography based on cardiovascular parameters

This study provides cuffless blood pressure estimation. In general, blood pressure changes when the subject´s condition changes, and it is important to estimate it continuously and noninvasively. In many previous studies, they used PTT (Pulse Transmission Time) for estimating. However, PTT needs both electrocardiogram and photoplethysmography to be measured. Our method needs only a finger type photoplethysmographic sensor for estimating. We use the features obtained only from photoplethysmography for estimating, instead of PTT obtained from electrocardiogram. The features used are accelerated plethysmography´s waveform, Heart Rate Variability and the rate of photoplethysmography´s drift. Blood pressure is modeled as the product of CO (Cardiac Output) and TPR (Total Peripheral Resistance) in general. Then, we estimated blood pressure as the product of eCO and eTPR estimated by proposed photoplethysmography´s features with Stepwise multiple regression analysis. Therefore, our proposed method provides not only blood pressure, but also CO and TPR. As of result, we estimated blood pressure based on eCO and eTPR, and we obtained r = 0.71. Therefore, we could obtain the result closer to Finometer in accuracy.