The cuffless arterial blood pressure estimation based on the timing- characteristics of second heart sound.

Continuous and non-invasive monitoring of blood pressure (BP) is important to prevent hypertensive patients from stroke and heart attack. However, most of the prevalent BP devices can provide solely intermittent measurements. In this study, a novel parameter RS2, defined as the time interval from the R wave of electrocardiographic (ECG) signal to the peak of second heart sound of phonocardiographic (PCG) signal, was used for BP estimation. Experiment was conducted on 66 normal and 19 abnormal subjects during resting condition. The results of this study showed that estimation error of systolic BP (SBP) and diastolic BP (DBP) was 2.0+/-7.5 mmHg and 0.9+/-5.1 mmHg respectively. 94.7% of the difference between measured and estimated SBPs was within +/-2 standard deviations in the Bland Altman plot. 93.4% of the difference between measured and estimated DBFs was within +/-2 standard deviations in the Bland Altman plot. The preliminary results illustrated that the RS2 is a promising parameter for continuous and non-invasive estimation of BP in homecare and mobile healthcare.