Initial study on pulse wave velocity acquired from one hand using two synchronized wireless reflectance pulse oximeters

Pulse wave velocity (PWV) has garnered attention as a means to estimate vessel elasticity. This paper presents an approach to measure PWV using two synchronized, wireless pulse oximeters placed on the wrist and fingertip of the same hand. A MATLAB interface acquires and time-aligns these incoming photoplethysmograms (PPGs), and then it calculates PWVs using time differences at three waveform features: the foot, inflection point, and peak of the rising slope in each PPG. Consistent with expectations, PWV values for inflection points are larger than those calculated at waveform feet, since PWV is known to increase with increased intra-arterial pressure. However, the presence of pulse wave reflections complicates the interpretation of PWVs calculated from the PPG peaks since the reflected components impose a varying time delay on the related peaks.