Blood pressure measurement based on pulse transit time from different positioned photoplethysmography signals

Abstract

To fulfill continuous blood pressure measurement, we developed a cuff-less blood pressure (BP) monitoring method which was based on the pulse transit time (PTT). We measured photoplethysmography (PPG) signals at two different positions simultaneously to solve the disadvantages of the cuff-based BP measurement, which was unsuitable for those had stiff artery issues or atrial fibrillation problems. Therefore, we replaced the inflatable cuff with two PPG pods which required just simple contact to the skin surface. With two optical pods being placed at two different positions, the PTT was calculated from the PPG waveforms. The time difference between the R-peak of an electrocardiogram (ECG) and the PPG foot point was traditionally taken as the PTT parameter for blood pressure model calculation. We replaced the calculation between the ECG and the PPG signals by detecting two PPG waveforms at the same time. The relationship between the PTT and BP (including systolic blood pressure (SBP) and diastolic blood pressure (DBP)) has been investigated and shown with high correlation.