Ambulatory venous pressure revisited

PURPOSE: The purpose of this study was to describe a method for measuring the deep venous pressure changes in the lower extremity and compare it with those obtained in the dorsal foot vein. METHODS: After cannulation of the posterior tibial vein, a catheter with a pressure transducer in its tip was inserted and placed at the knee joint level. The dorsal foot vein was also cannulated. Pressures were recorded simultaneously at both sites during toe stands and repeated with the probe in the upper, middle, and lower calf. RESULTS: The study was performed in 45 patients with signs and symptoms of chronic venous insufficiency. Duplex Doppler scanning and ascending and descending venography performed before pressure measurements revealed saphenous vein incompetence in 11 lower extremities, incompetent perforators in 11 extremities (eight were combined with saphenous incompetence), and marked compression of popliteal vein with plantar flexion in 28 extremities. No significant deep axial reflux was observed on duplex Doppler examination or descending venography. No morphologic outflow obstruction was detected. The mean deep pressure at the knee joint level fell during toe stands, -15% +/- 27 (SD), and the mean dorsal foot vein pressure drop was even more marked, -75% +/- 22 (SD). Although the exercise pressure in the dorsal foot vein decreased in all patients (range, 13-90% drop), the popliteal vein pressure increased (4-72%) in nine limbs, decreased only marginally if at all in 15 limbs (0-15%), and fell more markedly in 21 extremities (22-65%). Deep vein recovery time was considerably shorter overall as compared with the findings by the dorsal vein measurement. In the comparison of limbs with and without superficial reflux, the recovery times in the deep system were significantly shorter in limbs with superficial incompetence. CONCLUSION: Ambulatory dorsal foot venous pressure is not always accurate in detecting changes in the pressure of the tibial and popliteal veins. Although dorsal foot venous pressure may be normal, deep venous pressure may decrease to a lesser degree or even increase.