Cephalic vein dilatation at the elbow by preoperative supervised forearm exercise depends on adherence to therapy: Results from the randomized controlled single-blind PINCH trial.

Background: Maturation failure may be as high as 30%-60% of arteriovenous fistulas (AVF). Forearm exercise postoperatively has shown potential in increasing blood vessel size in patients with end-stage renal disease and may promote maturation of AVFs. Little evidence exists on the impact of pre-operative forearm exercises on the increase of vascular diameters. Aim of this study was to evaluate the effect of supervised forearm exercises on vascular diameters and AVF maturation.

Methods: The PINCH trial is a single-blinded, randomized controlled trial on supervised forearm exercises compared to no exercise 6 weeks before AVF creation. Forty-eight patients were included.

Primary endpoint: vascular diameters after 6 weeks of exercise. Secondary endpoints: cephalic vein diameters and blood flow 6 weeks after surgery and change in vascular diameters between baseline and after exercise after tourniquet application (vascular compliance).

Results: A non-significant increase of cephalic vein diameters at the elbow after exercise was found. Subgroup analysis of patients that showed increased forearm force after 6 weeks of training, revealed an increased diameter of the cephalic vein at the elbow with tourniquet inflation (+0.73 vs -0.25 mm, p = 0.037) and a greater increase in compliance of the cephalic vein at the elbow (+0.61 vs -0.34 mm, p = 0.045), when compared to patients without exercises. No difference in cephalic vein diameters at the level of the wrist, or in AVF maturation was found (50% p > 0.999).

Conclusion: The PINCH study was a randomized trial to evaluate the effect of pre-operative, supervised forearm exercises on vein diameters in patients with end stage kidney disease, and the first to evaluate supervised forearm exercises in this population. This trial shows that response to forearm exercise relies on adherence to the training program, with a positive effect on cephalic vein diameters at the elbow and a positive effect on the cephalic vein compliance without change in maturation rates.