Non-contact pulse transit time measurement using imaging camera, and its relation to blood pressure

This study reports pulse transit time (PTT) measurements of two areas of the human body (wrist and ankle) by a single imaging camera. The pulse peaks at both areas were extracted by finite impulse response (FIR) low-pass filtering and phase delay compensation. The interbeat intervals (IBIs) obtained by the camera and a photoplethysmogram sensor were almost identical, confirming the temporal accuracy of the camera-obtained peaks, and suggesting the utility of the camera in noncontact PTT measurements. Next, the PTTs were calculated from the time differences between the pulse peaks of the wrist and ankle images, and correlated with vital parameters such as blood pressure and age in ten subjects. A high correlation coefficient of (-0.88) was obtained between PTT and blood pressure, indicating a direct relationship between these two measures.