Investigation of photoplethysmographic signal augmentation index estimation differences between fingers

Abstract

Photoplethysmographic signal augmentation index (PPGAI), proposed in our previous study, correlates strongly with aortic augmentation index and it is possible to discriminate patients with increased arterial stiffness from healthy subjects. This pilot study was aimed to investigate the PPGAI estimation differences between fingers in healthy subjects. The 8 channel analog front-end was built for the synchronous registration of PPG signals from left and right hand fingers. The PPG signals were recorded from 10 healthy subjects. The PPGAI was estimated for each period of the recorded PPG signals. It was found that the average PPGAI values of left hand fingers are higher compared to the right hand. T-test revealed that the differences are statistically significant (P < 0.05). In addition, there were found statistically significant differences in PPGAI values between the fingers of left hand. As a conclusion the PPG signal should be registered from right hand for the PPGAI estimation. More detailed studies should be carried out about the bilateral PPG waveform differences using larger study group.