Preoperative exercise increases vein diameter in patients with arteriovenous fistula

Blood vessel diameters tend to increase following preoperative exercise therapy in patients undergoing radiocephalic arteriovenous fistula (AVF) creation, reaching statistical significance in those who are adherent to the prescribed exercise regimen, suggests a Singapore study.

“While not statistically significant, patients with AVF maturation and cannulation success also had a longer mean completion of exercise days,” the researchers said.

After the exercise therapy, the mean hand grip strength of patients improved to 21.9 kg from 20.3 kg (p=0.01). A statistically significant increase was noted in basilic vein diameter among those who showed strict compliance to at least 42 days of preoperative exercise therapy by 0.51 mm, from 3.23 to 3.75 mm (p=0.03). [Proc Singap Healthc 2023;doi:10.1177/20101058231188877]

Primary failure of newly created radiocephalic AVF occurred in seven of 28 patients (25 percent). This rate was similar to the previous series of 436 distal AVF created, which had a failure rate of 26 percent.

“Our study found that there was a statistically significant increase in basilic vein diameter only in [patients] who were fully compliant to the prescribed 6-week preoperative exercise therapy regimen,” the researchers said. “There was also a trend of increment in cephalic and basilic vein diameters regardless of adherence, albeit a nonstatistically significant one.”

In the analysis of Cohen’s d, a near-medium effect size was also observed for the increases in cephalic vein diameter at the mid-forearm, elbow, upper arm, and basilic vein diameter at the elbow (Cohen’s d, 0.39 to 0.46) among patients.

Such findings support those of previous studies, which demonstrated a significant increase in vasodilation and vessel diameters among patients with end-stage renal failure after 4 to 8 weeks of handgrip strength training. [J Vasc Access 2020;21:372-378; Blood Purif 2003;21:389-394]

Adherence

The statistical significance of basilic vein diameter increase in adherent patients highlighted the importance of adherence to a preoperative exercise regime.

Notably, “[t]he lack of strict adherence to the prescribed exercise therapy regime could be attributed to difficulty in enforcing daily exercises remotely and is a possible confounder towards the results of our study,” the researchers said. “Despite this, there was still a trend of increased cephalic and basilic vein diameters despite suboptimal compliance to the exercise regime.”

Specifically, 72 percent of patients were adherent to self-directed preoperative exercises for at least 28 days, the point at which marked changes were observed in venous diameters. [J Vasc Access 2020;21:372-378]

“There is room for future studies to evaluate if better compliance to our prescribed preoperative exercise therapy regime can effect further increment in vessel diameter sizes,” the researchers said.

To determine whether preoperative exercise therapy increases vessel diameter, the researchers recruited 34 patients who were set to undergo radiocephalic AVF creation at a tertiary university hospital. Participants went through 6 weeks of self-directed daily upper extremity exercises before the procedure and were then reviewed for 6 months postsurgery.

Change in venous and arterial diameters following exercise intervention was the primary outcome measured, while the primary failure rate of the newly created AVF served as the secondary outcome.

“Postoperative upper extremity exercise is recommended to patients with AVF,” the researchers said. “It is postulated that increased blood flow to vessels improves maturation and patency rates.”