Noninvasive and Cuffless Blood Pressure Estimation Using Photoplethysmography Index

Abstract

Noninvasive and cuffless blood pressure estimation is crucial for the early prevention, diagnosis and treatment of hypertension and related cardiovascular and cerebrovascular diseases. The noninvasive cuffless blood pressure measurement method based on pulse wave transit time (PTT) has been widely studied due to its noninvasive, low cost and simple operation. However, a single PTT cannot accurately track various changes in blood pressure. Therefore, it is necessary to explore new parameters other than PTT that can reflect blood pressure changes and be used for blood pressure estimation. This paper proposes the use of systolic area (SA) to estimate blood pressure, a feature that can be obtained from the photoplethysmographic signal (PPG). At the same time, we try to compare this feature with the pulse wave at half amplitude (PWHA) and the pulse wave amplitude (AM), which are also obtained from PPG, and use the method of multiple linear regression to fuse them. In addition, we did a controlled experiment to compare the traditional PTT-based method with the method based on these feature fusions. The results showed that when SA is used alone for BP estimation, for SBP and DBP, the accuracy is 0.004±6.55 mmHg and -0.09±3.52 mmHg, respectively. When PWHA, SA, AM and PTT are combined, for SBP and DBP, the accuracy is 0.29±4.97 mmHg and -0.14±3.06 mmHg, respectively. These results demonstrate that SA is a promising feature, and the method based on the above four features fusion can greatly improve the accuracy of blood pressure estimation. At the same time, it is also possible to rely solely on PPG signal to estimate blood pressure.