P18 Vascular Aging Index of the Finger Photoplethysmogram: A Validation Study with Vascular Stiffness, Mental Stress, and Day-to-Day Variability

Abstract

Background

Daily assessment of vascular health may predict cardiovascular incidence. Vascular aging index (VAI) calculated from second derivative of photoplethysmogram (SDPTG) is a simple, non-invasive measure possibly reflecting vascular stiffness. However, the effects of daily life events such as mental stress and day-to-day variability as well as its relation to other indices of vascular stiffness remain unclear.

Purpose

To determine whether VAI measured by finger SDPTG is 1) correlated with peripheral augmentation index (pAI), 2) altered by acute mental stress, and 3) affected by day-to-day variability.

Methods

Simultaneous measurements of finger photoplethysmogram and radial artery tonometry were performed in 68 healthy subjects (age = 22–64 years) of whom 31 subjects were further tested during a 30-second mental arithmetic and 10 subjects underwent day-to-day variability assessment for 5 consecutive days. VAI was calculated from a 20-second segment of photoplethysmogram data [1].

Results

At rest, VAI was positively correlated with pAI (r = 0.62, p < 0.001). During mental arithmetic, VAI increased when compared with the control condition (p = 0.032) whereas pAI did not show significant change. Five day measurements of VAI demonstrated the overall coefficient of variation of 21.1 ± 13.7% across all subjects.

Conclusion

VAI calculated from the finger SDPTG is related to a measure of vascular stiffness and sensitive to mental stress with fair day-to-day variability. These findings suggest that VAI assessment needs to be performed at the quiet resting condition.