Abstract
This paper presents a new method which achieves accuracy like cuff-based BP (Blood pressure) measurement to improve the conventional cuff-less BP estimation method for a wrist-type single PPG sensor. The conventional method used the modified normalized pulse volume and the pulse rate for resistance and flow rate respectively to express BP. However, it is required to improve the performance in comparison with methods based on pulse wave velocity which involve elasticity rate relating to vascular pressure. The new method incorporates both resistance which is derived from relative velocity and peripheral arterial elasticity based on vascular function to elevate the accuracy of diastolic BP estimation. Systolic BP is also improved by the sum of estimated pulse pressure with resistance and the estimated diastolic BP value. The accuracy comparison between the conventional and proposal method was performed by cross validation for estimated BP values in 5 seconds each by using wrist-type PPG signals. It is found that the estimated SBP and DBP of the conventional method differed from the reference BP by 3.9 (mean absolute error) ±12 (standard deviation) mmHg and 4.7 ± 11 mmHg respectively. In the proposal method, the differences of estimated values are 2.5 ± 7.2 mmHg and 2.7 ± 7.8 mmHg. When compared to the AAMI requirement (5 ± 8 mmHg for both SBP and DBP estimation), the results suggest that the proposed method has great potential for a single PPG sensor device.
