Cuffless and Continuous Blood Pressure Monitoring Using a Single Chest-Worn Device

Continuous blood pressure (BP) monitoring in daily life is needed to enable early detection of hypertension and improve its control. Although pulse transit time (PTT)-based BP estimation represents a promising approach, it still lacks of performance in systolic blood pressure (SBP) estimation and its use in daily life is limited owing to the requirement of bulky systems for measurement of PTT. This study aims at developing a wearable system providing continuous PTT measurement and enhanced SBP estimation for continuous BP monitoring. A single chest-worn device was developed, which measures the photoplethysmogram and seismocardiogram simultaneously, and thereby obtains PTT by time difference between two signals. A multivariate model using the seismocardiogram amplitude (SA) in conjunction with PTT was proposed for SBP estimation, and validated against 30 healthy males (31.47 ± 7.23 years old). Performance of the proposed model was compared with that of conventional univariate models using PTT or pulse arrival time in two types of BP interventions, and for the verification of real use in daily life, performance assessment with calibration and BP monitoring in daily life were conducted. The results suggested that the proposed model (1) outperformed the conventional models, (2) showed potential to be generalized with just a simple calibration, and (3) demonstrated the potential of continuous BP monitoring in daily life. In conclusion, the presented system provides an improved performance of continuous BP monitoring by using a combination of PTT and SA with a convenient and compact single chest-worn device, and thus, it can contribute to mobile healthcare services.