Measuring Pulse Transit Time From Finger and Facial Photoplethysmography for Arterial Stiffness Estimation

Frequent monitoring of arterial stiffness (AS) is crucial for the early prevention of cardiovascular diseases. Traditional AS estimation based solely on finger photoplethysmography (PPG) provides a convenient detection method, but its accuracy is limited. This study proposes a novel method for conveniently and accurately measuring AS using finger and face PPG. Firstly, we simultaneously collected PPG signals from both, utilizing linear phase filtering to remove noise interference while preserving the temporal characteristics of the pulse signals. Secondly, the Phase-Temporal Analysis (PTA) algorithm was introduced to enhance the accuracy of Pulse Transit Time (PTT) measurement from small time delays by combining wavelet phase coherence determination and cross-correlation temporal features. Finally, considering that increased AS affects pulse morphology, an XGBoost model was used to combine the measured PTT with PPG features, thereby improving the accuracy of AS estimation. Experimental results show that PTT measured using the PTA algorithm has a strong correlation with reference PTT (Male group: PCC = 0.81, Female group: PCC = 0.89), and the mean absolute error (MAE) of AS estimation is 66.35 cm/s for the male group and 56.25 cm/s for the female group. This method simplifies the AS assessment process, highlighting its potential for clinical applications in cardiovascular health monitoring.