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Acceleration Plethysmography for Ambulatory Vascular Monitoring: A Pilot Study
Date Issued
01-01-2023
Author(s)
Girish, V. V.
Raj Kiran, V.
Nabeel, Pm
Indian Institute of Technology, Madras
Indian Institute of Technology, Madras
Abstract
As frequent monitoring of vascular ageing is gaining importance and the lack of a wearable sensing technology to track it through changes in vascular stiffness, we have developed a wearable accelerometric device. It could capture changes in vascular stiffness using our empirically derived markers from the amplitude features of acceleration plethysmogram (APG) at the carotid artery site. An in-vivo study on 12 subjects was conducted to (a) identify a few amplitude-based markers from the APG that exhibit significant change to physiologically induced hemodynamic perturbation; and (b) compare the magnitude of response of these APG-derived markers with that of carotid local stiffness metrics (β, Ep, and AC) measured using a clinically validated device, ARTSENS® Pen. The APG signals were reliable (SNR > 38 dB) and the amplitude features of APG were repeatable (CoV < 10 %). By examining all the APG-derived markers that showed statistically significant differences (p < 0.05) between pre and post-exercise measurements, it was found that the markers (ab)*(a-c) and (a*b) were having a high magnitude of response among others. The response (expressed as a percentage difference in mean values between pre and post-measurements) of the APG-derived markers, (a-b)*(a-c) and (a*b) were 42.41 % and 40.55 %, respectively, which were comparable to the response of carotid local stiffness metrics, β (32.34 %) and AC (41.83 %). The results suggest the potential of APG-derived markers, (a*b) and (a-b)*(a-c) for tracking stiffness changes, and the pilot study demonstrated the ability of the device to capture stiffness changes for ambulatory monitoring purposes.