Proximal upper arm occlusion resulted in significantly greater brachial artery flow-mediated dilation (6.6%) compared to distal forearm occlusion (3.4%, P<0.05).
Does the position of the occlusion cuff and the addition of ischemic exercise affect flow-mediated dilation in the brachial artery of healthy men?
The magnitude of flow-mediated dilation correlates with peak blood flow and shear rate, but the prolonged FMD after upper arm occlusion suggests the mechanism differs depending on the occlusion cuff position.
Absolute Event Rate: 6.6% vs 3.4%
p-value: p=<0.05
Different magnitudes and durations of postocclusion reactive hyperemia were achieved by occluding different volumes of tissue with and without ischemic exercise to test the hypotheses that flow-mediated dilation (FMD) of the brachial artery would depend on the increase in peak flow rate or shear stress and that the position of the occlusion cuff would affect the response. The brachial artery FMD response was observed by high-frequency ultrasound imaging with curve fitting to minimize the effects of random measurement error in eight healthy, young, nonsmoking men. Reactive hyperemia was graded by 5-min occlusion distal to the measurement site at the wrist and the forearm and proximal to the site in the upper arm. Flow was further increased by exercise during occlusion at the wrist and forearm positions. For the two wrist occlusion conditions, flow increased eightfold and FMD was only 1 to 2% (P > 0.05). After the forearm and upper arm occlusions, blood flow was almost identical but FMD after forearm occlusions was 3.4% (P < 0.05), whereas it was significantly greater (6.6%, P < 0.05) and more prolonged after proximal occlusion. Forearm occlusion plus exercise caused a greater and more prolonged increase in blood flow, yet FMD (7.0%) was qualitatively and quantitatively similar to that after proximal occlusion. Overall, the magnitude of FMD was significantly correlated with peak forearm blood flow (r = 0.59, P < 0.001), peak shear rate (r = 0.49, P < 0.002), and total 5-min reactive hyperemia (r = 0.52, P < 0.001). The prolonged FMD after upper arm occlusion suggests that the mechanism for FMD differs with occlusion cuff position.
Betik et al. (Thu,) conducted a other in Healthy (n=8). Circulatory occlusion at different positions (upper arm, forearm, wrist) vs. Different occlusion cuff positions and ischemic exercise was evaluated on Flow-mediated dilation (FMD) of the brachial artery (p=<0.05). Proximal upper arm occlusion resulted in significantly greater brachial artery flow-mediated dilation (6.6%) compared to distal forearm occlusion (3.4%, P<0.05).