Validity And Repeatability Of A New Reactive Hyperemia Index Using Calibrated Pulse-Volume Recording In Evaluation Of Endothelial Function

Objective: Endothelial function is clinically important for evaluation of cardiovascular risk and its prediction, but its evaluating method is impractical for to use in the clinic. We aimed to assess the volume changes of brachial artery using calibrated pulse-volume recording with MultiLab Series II LHS (Unetixs Vascular, Inc. USA) as an alternative to evaluate endothelial function and compared with flow mediated dilation (FMD) measured by ultrasound.Design and method: Reactive hyperemia volume index (RHVI) was calculated as (average amplitude during reactive hyperemia / average amplitude at baseline -1) × 100. There were outliers, defined as < Q1–1.5 × (Q3-Q1) or > Q3+1.5 × (Q3-Q1) by Turkey's outlier rule, three from RHVI and two from FMD and excluded from analysis. And Thirty seven subjects (mean age: 39.04 ± 10.10 years, male 5) were recruited. Results: Mean systolic and diastolic blood pressures were 120.40 ± 15.27 and 75.22 ± 9.57 mmHg. Endothelial function (FMD) by ultrasound was 14.97 ± 6.13% and RHVI by plethysmography was 68.53 ± 64.77%, with the correlation coefficient of 0.3182 (p-value = 0.0229) between them. The regression was remained significant after adjustment with age, sex and body mass index (β = 3.555 (se = 1.749), p-value = 0.0481). Short-term (15-minute interval) and longer-term (1-week interval) reproducibility was tested. Intra-class correlation coefficient was 0.620 (95% confidence interval −0.080 to 0.910) with correlation of 0.6429 for short term and 0.693 (95% confidence interval 0.156 to 0.914) with correlation of 0.5879 for longer-term. Conclusions: This method may provide a simple and repeatable alternative for evaluating endothelial function, but need further studies in large volumes for its potential use in clinic.