Peripheral venous dilation using flow-mediated dilation response: A randomized crossover study

Venodilation is crucial in enhancing the success rate of peripheral intravenous cannulation. Flow-mediated dilation (FMD) is a vasodilatory response initiated by temporary ischemia followed by reperfusion. This crossover study aimed to test the hypothesis that FMD induces dilation of the peripheral veins of the forearm.

Fifteen healthy volunteers underwent the FMD and control conditions in a randomized order. FMD involved a 5-min occlusion of blood flow in the brachial artery, followed by reperfusion, achieved by inflating and deflating a cuff placed on the upper arm. The control condition involved participants remaining at rest. The primary outcome measure was a change in the cross-sectional area of the cephalic vein post-intervention. The secondary outcomes included changes in venous diameter and perfusion index (PI).

FMD significantly increased the cross-sectional area of the cephalic vein compared with the control condition (relative change to baseline: 37.7% (31.4) vs 2.2% (11.7)), with a mean difference of 35.4% (95% confidence interval (CI): 16.4-54.5, p = 0.001). Both longitudinal and transverse diameters were significantly expanded with FMD compared to the control (relative change to baseline: 15.7% (15.4) vs 2.6% (3.6), p = 0.004; 18.9% (15.6) vs -0.0 (10.2), p = 0.003, respectively). Additionally, PI significantly increased with FMD compared with the control (relative change to baseline: 77.8% (56.9) vs 14.6% (36.0)), with a mean difference of 63.2% (95% CI: 31.2-95.2, p = 0.001).

FMD application induced dilation of the cephalic vein of the forearm. The findings suggest that FMD is an effective technique for dilating the venous area and potentially improving the success rate of peripheral intravenous cannulation.