Development of a novel cuff-free method for monitoring arterial stiffness using remote photoplethysmography (rPPG)

In peripheral artery disease (PAD), monitoring of arterial stiffness is crucial as it helps in understanding and managing the condition appropriately. Currently, brachial-ankle pulse wave velocity (baPWV) is the most prevailing technique for disease monitoring due to its operational simplicity. However, this method may cause discomfort, particularly in vulnerable populations, due to cuff inflation during the measurement procedure. Therefore, we studied the applicability of a new cuff-free method for vascular assessment by performing remote photoplethysmography (rPPG) using video recorded with an RGB camera. The pulse detected by the rPPG method reflects the density of red blood cells in the superficial layer of the skin, and can be used to estimate the heart rate. As a result of comparing the pulse of rPPG method and that of preexisting blood pressure monitors on the basis of R-peak of ECG, a significant correlation was found between the two. Furthermore, we found a significant negative correlation between rPPG-PWV, based on the difference in pulse wave arrival times between the palm and sole, and preexisting baPWV. This result suggests that rPPG-PWV may be used as a substitute for baPWV.