Volume tests for chronic venous insufficiency: an appraisal

Chronic venous disease is increasingly treated surgically with a variety of experimental procedures. Noninvasive volume tests are commonly used before surgery to select patients and after surgery to assess results. Rapid volume changes are considered to indicate regurgitation. Rigorous statistical validation of tests and the confounding nature of unmeasured arterial inflow are seldom considered. Volume changes were measured in 29 control limbs and 35 limbs with venous disease, with mercury-in-silicone rubber strain gauges, for both exercise and elevation. Normalization for arterial flow permitted calculation of the regurgitation rate. Normal (95% confidence) limits for measured and calculated parameters were determined. Specificity was shown by the percent of normal parameter values for control limbs and sensitivity by the percent of abnormal values for extremities with venous disease. Arterial flow significantly altered volume curves. Normalization increased specificity and sensitivity significantly. Calf exercise tests, even normalized, were too insensitive to be reliable. Elevation tests were significantly more sensitive for determining regurgitation. However, exercise tests were useful and supplied important information about the calf muscle pump. We conclude that, as currently used, many limb volume test procedures are unsuitable but could be improved significantly by normalization to reduce the confounding effect of regional arterial flow and use of an elevation test to measure regurgitation.