Acute application of a transdermal nitroglycerin patch protects against prolonged forearm ischemia-induced microvascular dysfunction

Abstract

Introduction: Prolonged limb blood flow occlusion (ie, tourniquet application during limb surgery) causes transient microvascular dysfunction. We examined the ability of a local nitric oxide donor (transdermal nitroglycerin) administered during prolonged cuff forearm occlusion to protect against microvascular dysfunction and to alter brachial artery dilation.

Methods: Ten healthy men (28 ± 8 years) participated in the study. During the control visit, they completed three vascular occlusion tests in the right arm termed, PRE (5-min occlusion), POST_immediate (20-min occlusion), and POST_30min (5-min occlusion). During the nitroglycerin visit, subjects completed the same vascular occlusion tests, but with a nitroglycerin patch placed over the contralateral forearm during the 20-min occlusion test. Micro- and macrovascular function were assessed using the near-infrared spectroscopy-derived reperfusion upslope (reperfusion slope, %.s^-1 ) and flow-mediated dilation (%FMD), respectively.

Results: The reperfusion slope (1.44 ± 0.72%.s^-1 ) and the %FMD (15.0 ± 2.8%) of the POST_immediate test of the nitroglycerin condition were significantly (P < .05) higher than the reperfusion slope (1.01 ± 0.37%.s^-1 ) and %FMD (6.77 ± 1.8%) during the POST_immediate test of the control visit.

Conclusion: Transdermal nitroglycerin protects against ischemia-induced microvascular dysfunction and causes marked dilation of the brachial artery %FMD.

Keywords: flow-mediated dilation; microcirculation; near-infrared spectroscopy; nitroglycerin.