Aging Index using Photoplethysmography for a Healthcare Device: Comparison with Brachial-Ankle Pulse Wave Velocity

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Diagnostics

Background:

• Peripheral fingertip photoplethysmogram (PPG) signals contain information relevant to arterial wall stiffening during aging.
• Brachial-ankle pulse wave velocity (baPWV) is a clinical standard for assessing arterial stiffness with age.
• The acceleration photoplethysmogram (APG), a derivative of PPG, has shown correlations with atherosclerotic conditions.

Purpose of the Study:

• To investigate the association between age, baPWV, and APG.
• To identify a new aging index derived from APG signals for arterial stiffness assessment.
• To evaluate the potential of APG for use in healthcare devices for monitoring vascular aging.

Main Methods:

• Simultaneous measurement of APG and baPWV in 168 subjects (mean age 58.1 ± 12.6 years) over two months.
• Development of a preamplifier and motion artifact removal algorithm for high-quality PPG signal acquisition.
• Analysis of APG indices, including the B ratio, and their correlation with age and baPWV.

Main Results:

• Significant correlations were found between age and both baPWV (r = 0.6685, p < 0.0001) and the APG B ratio (r = -0.4025, p < 0.0001).
• Regression analysis indicated that the c and d peaks of the APG were independent of age (r = -0.3553, p < 0.0001 and r = -0.3191, p < 0.0001, respectively).
• The B ratio emerged as a significant aging index reflecting arterial stiffness.

Conclusions:

• The B ratio derived from APG signals represents an improved aging index for arterial stiffness.
• APG analysis may provide information comparable to baPWV for assessing vascular aging.
• The findings suggest APG's utility in developing new healthcare devices for monitoring arterial health.