New Aging Index Using Signal Features of Both Photoplethysmograms and Acceleration Plethysmograms.

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Gerontology

Background:

• Acceleration plethysmograms (APGs) are derived from photoplethysmograms (PPGs) and offer insights into circulatory dynamics.
• Mobile health monitoring is increasingly utilizing PPG signals for noninvasive health assessments.
• Age-related changes in vascular function are significant risk factors for atherosclerosis.

Purpose of the Study:

• To develop and validate a novel feature from APG and PPG signal morphologies.
• To identify dominant indices reflecting age-related changes in blood volume pulsatility.
• To assess the efficacy of a new combined index in classifying vascular aging.

Main Methods:

• Simultaneous extraction of ten APG and fourteen PPG indices from 93 healthy adults (aged 36-86).
• Comparison of indices using Pearson correlation coefficients and regression analysis.
• Introduction of a combined index, inflection point area plus d_peak (IPAD), from both PPG and APG signals.

Main Results:

• APG indices (d_peak, age index) and PPG index (A1 time) showed significant correlations with age.
• The stiffness index was not found to be age-related.
• The combined IPAD index demonstrated a significantly stronger correlation with age (r=0.56, p<0.001) than all other individual indices.

Conclusions:

• The novel IPAD index significantly outperforms 24 other indices in evaluating vascular aging.
• IPAD is a promising, noninvasive indicator of age-related vascular changes.
• This index effectively captures clinical information within the PPG waveform for assessing vascular health.