NON-INVASIVE MEASUREMENT OF MICROVASCULAR BLOOD FLOW DURING MILD EXTERNAL COM

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Venous hypertension is associated with decreases in capillary density, arterial inflow, and local blood flow of the leg. Decreased perfusion adversely affects wound healing and viability of tissue, especially in patients with peripheral vascular disease. We hypothesize that mild external compression can restore the decreases in skin and muscle blood flow induced by venous hypertension, and that patients with higher central venous pressures resulting from heart failure will have greater increases in microvascular blood flow induced by leg compression compared to patients with lower central venous pressures and to healthy subjects. Thigh venous occlusion will be used as a model for venous hypertension in healthy subjects, skin and muscle blood flow will be measured using Photoplethysmography (PPG) before, during, and after external compression, and muscle oxygenation will be measured with Near Infrared Spectroscopy (NIRS). In addition, skin and muscle blood flow responses to external compression will be measured in patients with documented venous hypertension or heart failure. Our specific aims are: To measure Muscle Blood Flow (MBF) and Skin Blood Flow (SBF) microcirculatory increases in the leg caused by mild external compression in healthy subjects and patients with Chronic Venous Insufficiency (CVI). To measure muscle oxygenation changes in the leg caused by mild external compression in healthy subjects and patients with Chronic Venous Insufficiency (CVI). To optimize pressures of Continuous Compression to induce maximum microcirculatory blood flow in healthy subjects and patients with CVI. To optimize compression pressures, duration, and frequency of Intermittent Pneumatic Compression (IPC) to induce maximum microcirculatory blood flow in healthy subjects and patients with CVI.