Venous outflow and inflow resistance in health and venous disease

Purpose: The purpose of this study was to develop a physiologic method to m easure out-flow and inflow from the lower extremities and thus to quantify the degree of venous valvular insufficiency and venous obstructive disease. Methods: Calibrated photoplethysmography was used in combination with passi ve changes in hydrostatic pressure, by leg elevation followed by reposition ing of the leg to the original sitting position, With the principle of veno us occlusion plethysmography, timed volume changes were then used to calcul ate the outflow and inflow. The inflow and outflow units were the percentag e of optical reflectance (%OR) per minute. The respective resistances were calculated by identifying the hydrostatic pressure distance from the third intercostal space to the probe site that is inducing these site changes. Th e resistance units were millimeters of Mercury x minutes per %OR Results: I;our groups of subjects were examined: normal individuals, patien ts with venous valvular insufficiency, deep venous thrombosis, and a combin ation of both, The most significant differences in outflow values were foun d between the control group (81.77% OR/min) and the deep venous thrombosis group (28.47% OR/min). In contrast, the most significant differences in inf low values were found between the control group (9.67% OR/min) and the veno us valvular insufficiency group (108.61% OR/min). The resistances changed c orrespondingly Conclusion: The application of calibrated photoplethysmography in conjuncti on with induced changes in leg hydrostatic pressure proved to be an effecti ve physiologic method to noninvasively quantity venous hemodynamics in norm al control subjects, patients with venous valvular insufficiency venous obs tructive disease, or both.