Pulse Wave Velocity Assessments Derived From Photoplethymography: Reliability And Agreement With A Referent Device

Abstract

PURPOSE: Pulse wave velocity (PWV) is a common measure of arterial stiffness. Photoplethysmography (PPG) permits continuous measurement of PWV at multiple arterial segments simultaneously. The purpose of this study was to determine whether a simple, non-invasive PPG PWV method agrees with a referent measure, and to determine whether a posture-mediated change in PPG PWV agrees with change in the referent. METHODS: PPG, with electrocardiogram, measured heart-toe (htPWV) and heart-finger (hfPWV) PWV. Referent measurements were carotid-ankle PWV (caPWV) and carotid-wrist PWV (cwPWV) determined using the Vicorder device. In 30 adults (24.6 ± 4.8 y, body mass index 25.2 ± 5.9 kg/m2, 18 F), three measurements were made: i) two baseline measurements and ii) one measurement 5 minutes after a modified head-up tilt test (mHUTT, 78°). Baseline measurements were used to calculate measurement reliability via intraclass coefficient correlation (ICC). Mixed-models were used to calculate between-measure (overall agreement between PPG and referent), and between-condition (change in PPG versus change in referent) agreement between devices. RESULTS: All measures were reliable (ICC > 0.75). For hfPWV there was strong (ICC 0.7–0.9) between-measure agreement (ICC: 0.78, 95%CI: 0.67 – 0.85), but negligible (ICC < 0.2) and non-significant between-condition agreement (ICC: 0.10, 95%CI: 0.12 – 0.31). The lack of between-condition agreement may be attributable to the non-change in hfPWV and cwPWV with mHUTT. For htPWV, there was moderate (ICC 0.4–0.7) between-measure agreement (ICC:0.51, 95%CI: 0.32 – 0.65) and very strong between-condition agreement (ICC: 0.90, 95%CI: 0.85 – 0.94). CONCLUSION: PPG can be used to continuously measure PWV at multiple arterial segments with acceptable reliability and agreement with a referent.