Influence of thigh blood flow upon the arterial pressure gradient over the collateral arteries in patients with occlusion of the superficial femoral artery.

Abstract

The effect of circulatory arrest of the calf and foot and head-up tilt upon pressure gradient over the thigh and distribution of muscle blood flow in the thigh was studied in 14 patients with occlusion of the superficial femoral artery. In the supine position circulatory arrest just below the knee initially reduced the directly measured mean arterial pressure gradient over the thigh by about 30% indicating that a similar proportion of total leg blood flow supplied the calf and foot. Local muscle blood flow was measured by the local 133Xe washout technique proximally and distally in the thigh muscle. Total leg blood flow was measured by an indicator dilution technique. During 10 min of circulatory arrest of the calf and foot local muscle blood flow in the thigh increased by approximately 35% proximally and distally. Total leg blood flow remained unchanged and the pressure gradient was reduced by about 10% as compared with that before tourniquet. During head-up tilt local muscle blood flow in the thigh decreased by about 30% proximally and distally. Total leg blood flow also decreased by about 30%. Circulatory arrest below the knee did not alter this response. These findings indicate that blood flow change uniformly in the thigh during head-up tilt and during tourniquet on the calf. Furthermore blood flow to the calf appears only to account for 30% of the arterial pressure drop over the collateral arteries in the thigh, indicating that thigh blood flow is of major importance for the pressure gradient over the collateral arteries.