Noninvasive tests have been developed to provide qualitative and quantitative information that can offer answers to most questions posed in venous diseases. While duplex scanning is used to assess the macrocirculation, microcirculatory methods assess and quantify venous microangiopathy. Laser Doppler flowmetry is used to assess tissue viability and perfusion. Transcutaneous PO2 and PCO2 measurements are used to study venous hypertension, and strain-gauge plethysmography (SGP) is used to assess capillary filtration. In venous hypertension fluid filtration into the extracapillary compartment is increased. The increase in filtration is associated with a decreased venoarteriolar response. To quantify capillary filtration two methods have been developed: venous occlusion plethysmography and rate of ankle swelling. These methods quantify filtration into the extracapillary compartment and therefore are an indication of the formation of edema, which is the most frequent sign of venous hypertension. Other methods such as the vacuum suction chamber and the edema tester can be used to assess changes due to treatment in chronic venous hypertension. These methods have been used and validated in several experimental and clinical studies. The techniques described in this article were used in controlled environmental conditions. Results were consistent with clinical problems and data from previous studies from our group and from data from other investigators.
