External compression increases forearm perfusion.
Application of compression stockings to the lower extremities is a widely used therapeutic intervention to improve venous return, but there is little information about the effects of compression on local arterial perfusion. Therefore, we tested the hypothesis that a positive external pressure increases forearm perfusion. The relation of increasing external pressure induced by standardized compression to the arterial inflow and arterial flow reserve of the forearm was critically evaluated in a group of healthy young men (n = 9). Flow was measured with venous occlusion plethysmography after a 10-min application of six different stockings with compression pressure increasing from 13 to 23 mmHg. During compression, the arterial inflow increased significantly from 3.7 +/- 0.85 to 8.8 +/- 2.01 ml.min(-1).100 ml tissue(-1) (P < 0.001) and the arterial flow reserve increased from 17.7 +/- 4.7 to 28.3 +/- 7.0 ml.min(-1).100 ml tissue(-1). The flow increase was persistent after 3 h of constant application of external pressure and also during simultaneous low-intensity hand grip. Similar results obtained with occlusion plethysmography were seen with MRI. During the interventions, forearm temperature was unchanged, and the volunteers reported no discomfort. In conclusion, 1) arterial perfusion of the human forearm increases more than twofold during application of external compression over a pressure range of 13-23 mmHg, and 2) the result is interpreted as an autoregulatory response following the decrease of the vascular transmural pressure gradient.