Inter‐relationships between Noninvasive Measures of Peripheral Vascular Reactivity

The clinical importance of peripheral vascular reactivity as an early marker of atherosclerosis has been well established. The relation between different methods employed to provide measurements of peripheral vascular reactivity are unclear as each technique evaluates different physiological aspects related to micro‐ and macro‐vascular reactive hyperemia. To address this, a total of 40 apparently healthy normotensive adults (age 19–68 yrs, 28 males) underwent 5‐minutes of suprasystolic forearm cuff‐induced ischemia followed by post‐ischemic measurements. Macrovascular reactivity measures included flow‐mediated dilatation (FMD) of brachial artery, and brachial to radial pulse wave velocity (ΔPWV; via Doppler flowmeters). Microvascular reactivity measures included reactive hyperemia index (RHI) assessed by fingertip arterial tonometry (RHI; via EndoPAT, Itamar) and fingertip temperature rebound (TR; via VENDYS, Endothelix). FMD was significantly and positively associated with RHI (r=0.54) and TR (r=0.44). There was a modest positive association between TR and RHI (r=0.29). ΔPWV was not significantly associated to any other measures. We concluded that different measures of peripheral micro‐ and macro‐vascular reactivity were not well correlated. These results suggest that a multi‐faceted approach may be necessary for the comprehensive assessment of peripheral vascular function.