Photoplethysmographic Waveform as a Function of Subject's Age

In this report we present the experimental study of imaging photoplethysmography in the area of the palm and wrist of fifty-six healthy subjects. We found that the amplitude of the PPG waveform is unevenly distributed over the studied area forming the hot spots with the elevated amplitude. There is clear tendency of the amplitude increasing in the hottest spots with the age of the subject. These observations support the recently proposed model of photoplethysmography in which pulse oscillations of the arterial transmural pressure deform the connective-tissue components of the dermis resulting in periodical changes of both the light scattering and absorption.