Upper arm occlusion cuff position produced a significantly greater maximal brachial artery flow-mediated dilation compared with forearm occlusion (9.0% vs 5.9%, P=0.01).
RCT (n=28)
Randomly assigned
Does upper arm occlusion cuff position compared to forearm occlusion affect the magnitude and time course of brachial artery flow-mediated dilation in healthy subjects?
Upper arm occlusion produces a significantly greater flow-mediated dilation and delayed time to peak dilation compared to forearm occlusion, highlighting the critical need for standardized methodology in FMD studies.
Absolute Event Rate: 9% vs 5.9%
p-value: p=0.01
Non-invasive ultrasound techniques to assess flow-mediated vasodilation (FMD) are frequently used to assess arterial endothelial vasodilator function. However, the range of normal values varies considerably, possibly due to differences in methodological factors. We sought to determine the effect of occlusion cuff position on the time course and magnitude of brachial artery blood flow and flow-mediated dilation. Twelve healthy subjects underwent measurements of forearm blood flow using venous occlusion plethysmography (VOP) before and after 5 min of susprasystolic cuff inflation, using two randomly assigned occlusion cuff positions (upper arm and forearm). An additional 16 subjects underwent two brachial ultrasound studies, using the two cuff positions, to assess the extent and time course of changes in brachial artery diameter and blood flow. Maximum increase in blood flow (peak reactive hyperaemia), measured by VOP, occurred immediately upon each cuff deflation, but was greater after upper arm compared with forearm arterial occlusion (33.1+/-3.1 versus 22.8+/-2.2 ml/min per forearm tissue, P=0.001). Maximal brachial artery FMD was significantly greater following upper arm occlusion (9.0+/-1.2%, mean +/- S.E.M.) compared with forearm occlusion (5.9+/-0.7%, P=0.01). The time course of the change in brachial artery diameter was affected differently in response to each protocol. The time to peak dilation following upper arm occlusion was delayed by 22 s compared with forearm occlusion. Occlusion cuff position is thus a powerful determinant of peak reactive hyperaemia, volume repaid and the extent and time course of brachial artery FMD. Positioning the cuff on the upper arm produces a greater FMD. These results highlight the need for comparisons between FMD studies to be made with care.
Berry et al. (2000) conducted an RCT in Healthy subjects (n=28). Upper arm occlusion cuff position vs. Forearm occlusion cuff position was evaluated on Maximal brachial artery flow-mediated dilation (p=0.01). Upper arm occlusion cuff position produced a significantly greater maximal brachial artery flow-mediated dilation compared with forearm occlusion (9.0% vs 5.9%, P=0.01).