Background: Venous occlusion plethysmography (VOP) is a methodology that was originally reported in the literature by A.W. Hewlett and J.G. Van Zwaluwenburg in 1909 . The technique describes an approach to measure blood flow based from factors affecting the forearm vasculature. Since the methodology has been formally presented in the published literature, countless of articles have documented the clinical utility of VOP and is currently the key method for evaluating the physiological responses to various doses of drugs modulating the cardiovascular system. Throughout this time, physicians and scientists evaluating the mechanisms of vasodilation and vasoconstriction have used various compounds to test arterial response based on endothelial dependence (e.g. Acetylcholine or Bradykinin), endothelial independence (e.g. Sodium Nitroprusside or Glyceryl Trinitrate), or other mechanisms like the calcium channel blocking effects of drugs (e.g. Verapamil).
Andy R. Eugene