Methodical aspects of pneumatic segment plethysmography. I. The problem of posture and distal venous occlusion

: Pneumatic segment-plethysmography was used to investigate the influence of the position and of distal venous occlusion on the arterial inflow to the calf and on the pressure-dependent venous capacity. It was demonstrated that (1) two of three investiaged positions have no significant influence on the arterial inflow to the calf; (2) the pressure-dependent venous capacities, however, show statistically significant differences related to position of the leg. The following reasons for these results were discussed: the varying tension of the surrounding tissue of the vessels, the basic volumes and the relation of intravenous pressure and the flexibility of the vessels. (3) It could be shown that the arterial inflow at rest measured without distal venous occlusion is significantly higher than the flow measured with distal venous occlusion. (4) On the contrary distal venous occlusion is of no importance in reactive hyperemia after 3 minutes of arterial obstruction. The arterial inflow to the following distal tissue was assumed to be the reason of these findings.