Venous pressure-volume relation and calf blood flow determined by changes in posture

The volume capacity of the venous system in the calves of 70 normal subjects was determined by passive and active changes in posture, using mercury-in-rubber strain gauges. The mean volume capacity was 1.26% (SD 0.39%) at a venous pressure of 0 kPa (o mm Hg) and 2.05% (SD 0.70%) at 1.60 kPa (12 mm Hg). With this method the blood flow in the calves at rest was measured without venous occlusion: 2.84 ml-100 ml-1/min (SD 1.20). During interpolated venous occlusion the mean blood flow was 2.67 ml-100 ml-1/min (SD 1.21). The pressure-volume relation over the pressure range 0 to 9.31 kPa (0 to 70 mm Hg) was determined in seven normal subjects.