Validation of the supine venous pump function test: a new non-invasive tool in the assessment of deep venous insufficiency.

1. A new non-invasive test was developed to assess calf muscle pump function: the supine venous pump function test. The technique uses strain-gauge plethysmography and is performed in the supine position. The method is superior to other non-invasive methods because basically the most essential haemodynamic parameter, venous pressure decrease, is used by properly converting venous volume measurements into venous pressure. The validity of this test was established by comparison with invasive venous pressure measurements and by determining the reproducibility. Additionally, normal values were determined. 2. In 28 extremities the supine venous pump function test was performed simultaneously with invasive venous pressure measurements. The reproducibility of the test was assessed in 10 randomly chosen volunteers. In 34 volunteers normal values were obtained and 26 patients with clinical venous insufficiency were examined. 3. Comparison of the two methods revealed a correlation coefficient of r = 0.98 (P < 0.001). A mean difference of 3.9%pf between both methods was found with limits of agreement of -6.3%pf to 14.1%pf. The coefficient of repeatability was 13%pf and the coefficient of variation was 9%. The normal range was found to be > 60%pf. The mean pump function in the patient group was 45%pf. 4. The limits of agreement are small enough to be confident that the supine venous pump function test can be used instead of invasive venous pressure measurements to assess calf muscle pump function in clinical practice. The reproducibility of the test is good.