ABSTRACT
BACKGROUND: Impairments at the microvascular level might lead to more overt cardiovascular complications, therefore, being able to early detect microvascular dysfunction would be beneficial. Thus, the present study investigated whether near-infrared spectroscopy (NIRS) assessment of microvascular responsiveness (reoxygenation slope, %.s-1) would detect the detrimental effects on the forearm microvasculature following a period of arterial occlusion. Similarly, the effects of prolonged forearm ischemia on brachial artery function were also assessed by flow-mediated dilation (%FMD). METHODS: Fourteen individuals were tested before (Pre), immediately after (PostPI), 30â¯min after (Post30), and 60â¯min after (Post60) prolonged forearm ischemia. The Pre, Post30, and Post60 interventions consisted of 5â¯min of blood flow occlusion, whereas the postPI involved a 20-min occlusion period. RESULTS: The reoxygenation slope was reduced at PostPI (1.33⯱â¯0.72%.s-1 vs. 1.79⯱â¯0.68%.s-1 Pre; pâ¯<â¯0.05), but not at Post30 (1.93⯱â¯0.70%.s-1) and Post60 (1.87⯱â¯0.85%.s-1) (both pâ¯>â¯0.05 vs. Pre). Similarly, the brachial FMD response was reduced at PostPI (7.4⯱â¯3.9% vs. 10.9⯱â¯2.9% Pre; pâ¯<â¯0.05), but not at Post30 (11.3⯱â¯4.1%) or Post60 (11.8⯱â¯4.3%) (both pâ¯>â¯0.05 vs. Pre). CONCLUSION: These findings show that NIRS-derived reoxygenation slope detects the transient detrimental effects of prolonged ischemia within the forearm microvasculature. Additionally, this study found that the reduction in forearm microvascular responsiveness might have contributed to the decreased brachial artery FMD responsiveness.
