Inter-individual differences in the ischemic stimulus and other technical considerations when assessing reactive hyperemia.

Inter-individual differences in the ischemic stimulus and other technical considerations when assessing reactive hyperemia. Am J Physiol Regul Integr Comp Physiol. 2019 Jul 17;: Authors: Rosenberry R, Trojacek D, Chung S, Cipher DJ, Nelson MD Abstract Reactive hyperemia is an established, non-invasive technique to assess microvascular function, and is a powerful predictor of all-cause and cardiovascular morbidity and mortality. Emerging evidence from our lab suggests that reactive hyperemia is closely linked to the metabolic rate of the ischemic limb, and that large inter-individual differences exist, contributing to markedly different stimuli to vasodilate. Here we relate forearm tissue desaturation (i.e. the ischemic stimulus to vasodilate, measured by near-infrared spectroscopy) with brachial artery hyperemic velocity and flow (measured using duplex ultrasound), across a wide range of ischemic stimuli. Twelve young and eleven elderly individuals were prospectively studied. To recapitulate conventional vascular occlusion testing, reactive hyperemia was first assessed using a standard 5-minute occlusion period. Then, to evaluate the dose-dependency of tissue ischemia on reactive hyperemia, we then randomly performed 4-, 6-, and 8-minute cuff occlusions in both groups. In all cases, peak velocity, as well as the 5 second average velocity, immediately after the cuff occlusion was significantly higher in the young group, compared to th...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - Category: Physiology Authors: Tags: Am J Physiol Regul Integr Comp Physiol Source Type: research