Rationale and design of the PHYSICALFAV trial: a randomized controlled trial to evaluate the effect of preoperative isometric exercise on vascular calibre and maturation of autologous arteriovenous fistulas.

Background: A good vascular access (VA) is vital for haemodialysis (HD) patients. HD with an autologous arteriovenous fistula (AVF) is associated with higher survival, lower health care costs and fewer complications. Although a distal forearm AVF is the best option, not all patients are good candidates for this approach and the primary failure rate ranges from 20% to 50%. The optimal AVF depends mainly on the anatomical and haemodynamic characteristics of the artery and the vein chosen for the anastomosis. These characteristics can be modified by performing physical exercise. VA guidelines suggest that isometric exercises should be performed both before and after the AVF is created. While the literature contains few data on the potential efficacy of preoperative exercise, small observational studies point to an improvement in venous and arterial calibre. Postoperative exercise also seems to improve maturation, although there is no consensus on the appropriate exercise protocol.

Methods: The PHYSICALFAV trial (NCT03213756) is an open-label, multicentre, prospective, controlled, randomized trial designed to evaluate the usefulness of preoperative isometric exercise (PIE) in pre-dialysis patients or in prevalent HD patients who are candidates for a new AVF. Patients are randomized 1:1 to the PIE group (isometric exercises for 8 weeks) or the control group (no exercise). The main endpoint is whether the rate of primary failure is lower in the PIE group than in the control group.

Results: The trial has already started, with 40 patients having been enrolled as of 21 March 2018; 26.5% of the estimated sample.