Biphasic venous emptying from the calves in venous-occlusion plethysmography.

The pathophysiological significance of the biphasic venous emptying curves from the lower limbs in venous occlusion plethysmography was examined in three patients peroperatively by clamping the iliac veins in different locations. The clinical significance of biphasic curves was analysed in fifty-four patients, thirty-one of whom were pregnant and twenty-three had a suspected deep vein thrombosis. It was found that the primary venous emptying time (PVET) was helfpul in locating the obstruction. Patients with femoral and pelvic vein thrombosis had shorter PVET than patients with pregnancy or other pelvic vein obstructions. With PVET of 0.5 sec, or shorter, thrombosis should be strongly suspected. The ratio between the slow and fast emptying phases was useless in localization of the intrapelvic process.