Impact of a 6-Week Preoperative Exercise Program on AVF Outcomes in ESKD: Real World Experience

Introduction

ESKD is a growing public health concern in India, and hemodialysis (HD) is a life-sustaining therapy for many patients.^1,2 An autogenous arteriovenous fistula (AVF) is internationally recognized as the gold standard for HD access because of superior longevity and lower rates of infection and complications than grafts or central venous catheters.^3,4 The National Kidney Foundation (NKF) KDOQI guidelines recommend a “distal to proximal” strategy for AVF creation, often starting with a radiocephalic AVF.⁵

Despite these advancements, primary AVF failure occurs in a substantial proportion of patients, often due to non-maturation. It is reported to be between 20% and 60% globally.^6,7 Inadequate vessel diameter and insufficient blood flow are key modifiable risk factors for non-maturation.^8,9 Although postoperative exercises are commonly advocated to promote AVF maturation by increasing blood flow, evidence supporting their efficacy is not unequivocal.¹⁰

Interest in the potential benefits of preoperative exercise therapy is ongoing. It is hypothesized that targeted exercises can induce vasodilation and potentially promote adaptive vascular remodeling, leading to increased vessel diameters even before surgery.^11,12 This could improve vessel suitability for AVF creation, particularly in patients with borderline vessel sizes, and subsequently enhance maturation and patency rates. Limited studies, primarily from Western and other Asian populations, have shown promising results.^13-15 This study aimed to investigate the effect of a preoperative upper limb exercise program on vessel diameter and AVF maturation in an Indian cohort of patients with ESKD at a quaternary care referral institute.

Materials and Methods

This was a single-center, prospective, non-randomized study conducted at the Department of Urology, AIIMS Patna, between January 2024 to February 2025. Written informed consent was obtained from all participants. This is a report of the protocol followed at the Department of Urology in our Institute and not a research intervention. Hence, ethical approval was not taken.

Thirty-five adult patients with ESKD scheduled for first-time radiocephalic AVF creation were screened. The inclusion criteria were: age 18-75 years, planned radiocephalic AVF, and willingness to participate in an exercise program. Patients were required to have a minimum cephalic vein diameter of 1.6 mm and a radial artery diameter of 1.6 mm, as assessed by preoperative duplex ultrasound mapping. The exclusion criteria were as follows: previous AVF or graft on the ipsilateral limb, active infection, severe ischemic heart disease or peripheral vascular disease affecting the limb, significant cognitive impairment preventing adherence to the exercise protocol, and inability to attend follow-up.

Participants were enrolled in a 6-week structured, self-directed, home-based upper limb exercise program for the arm planned for AVF surgery. The exercise regimen was demonstrated by a trained study coordinator, and an illustrated pamphlet was provided. The exercises have been illustrated [Supplementary Figure 1].

• 1.

  Elbow flexion-extension: Using a DomyosBand® (medium resistance (yellow) = 25 kg), 10 repetitions ´ 2 sets were performed daily.

• 2.

  Wrist flexion and extension: Using a DomyosBand®, 10 repetitions ´ 2 sets were performed daily.

• 3.

  Hand grip exercises: Using a hand-grip strengthener (∼10 kg resistance), 20 repetitions ´ 2 sets daily. All exercises were performed while seated, with the elbow flexed at ∼90° for handgrip and wrist exercises.

Adherence was monitored by weekly phone calls by the study coordinator and self-reported exercise logs. The study coordinator maintained a checklist of days on which the patients complied with the exercise protocol. After 6 weeks, this was reviewed. “High adherence” was defined as completion of the prescribed exercises in at least 34 days (i.e., ≥ 80% of exercise protocol days). Due to the lack of an established cut-off for defining adherence for AVF-related exercises, 80% was chosen from prior studies reporting exercise protocols.^16,17 Each phone call emphasized the need for exercises. If patients asked for a repeat training session, they provided the same during follow-up visits. After AVF creation, assessment using Doppler ultrasound was done biweekly for 6 weeks. After maturation, no surveillance ultrasound was done.

The primary outcomes were the change in cephalic vein and radial artery diameters at the wrist and mid-forearm, and hand grip strength measured before and after the 6-week exercise program. Vessel diameters were measured using duplex ultrasound by a single experienced vascular sonographer to minimize interobserver variability. Measurements were taken at standardized anatomical locations with the patient in a supine position, after 5 min of rest, with a tourniquet applied to the upper arm inflated to 40 mmHg pressure. Hand grip strength was measured using a digital hand dynamometer (Easycare), taking the mean of three attempts with adequate rest between attempts.

The secondary outcome was the primary AVF failure rate 6 months after surgery. Primary failure was defined as an AVF that never developed sufficiently to allow successful two-needle cannulation for HD or failed within the first 3 months.¹⁸ AVF was created by consultant urologists or senior residents under supervision, using a standardized end-of-vein to side-of-artery anastomosis technique, typically under local or regional anesthesia, according to the surgeon’s preference.

Demographic data, ESKD etiology, and comorbidities were recorded at baseline. Follow-up assessments were conducted for 6 weeks, 3 months, and 6 months after surgery.

Results

Of the 35 patients initially recruited, two dropped out before completing the program (one due to intercurrent illness and one to follow-up), and two had their AVF surgery cancelled as one proceeded to kidney transplant and one opted for peritoneal dialysis. One patient was lost to follow-up after 4 weeks. Thus, 30 patients completed the preoperative exercise program, underwent AVF creation, and were included in the final analysis, as shown in Figure 1.

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Figure 1:

Flowchart of study participants. AVF: Arteriovenous fistula.

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The demographic and baseline clinical characteristics of the 30 participants have been presented in Table 1. The mean age was 56.5±11.2 years, and 20 (66.7%) patients were male. Diabetes mellitus was the most common cause of ESKD (53.3% of cases). All patients were undergoing predialysis care. The mean duration of exercise therapy was 43.5±8.2 days, with 18 patients (60%) classified as having “high adherence” (≥ 34 days, i.e., 80% of the protocol).

Discussion

The primary findings suggest that a 6-week preoperative upper limb exercise program, i.e., prehabilitation, is feasible and can lead to significant improvements in handgrip strength. We have found that strict adherence to protocol, despite telephonic reinforcement and supervision, is not universal and may be the most important factor in improvement of vein diameters. Improvement in handgrip strength is not a direct measure of vascular change, but improved forearm muscle strength can contribute to increased basal blood flow and may indirectly support vascular health.^19,20 This finding is consistent with numerous studies on resistance training in various populations, including those with CKD.^14,15 The improvement in cephalic vein diameters was seemingly modest, but such increments can be crucial in patients with borderline vessel sizes.^8,9 Several studies have established a strong correlation between pre-operative vein diameter and AVF maturation and patency.^20,21 For instance, Bashar K et al. suggested that a cephalic vein diameter ≥2.5 mm is associated with a higher likelihood of successful AVF maturation.¹⁸ Our intervention helped some patients approach or exceed the threshold value. The physiological basis for exercise-induced vasodilation and potential remodelling involves several mechanisms, including increased shear stress, leading to endothelial nitric oxide release and potentially long-term structural adaptations.^11,12,19,22 Our findings are consistent with those of Ong et al., Kumar et al., and Rus et al., who reported increased upper limb vein diameters following preoperative or isometric exercise in patients with CKD or ESKD.^13-15

The absence of significant change in radial artery diameter in our study mirrors findings from prior reports.^13,15 Given their thicker, less compliant walls, arteries may require more prolonged or intensive exercise to exhibit remodeling.^12,23 Nevertheless, enhancing venous caliber remains the primary target for AVF creation. While Dinenno et al. showed arterial remodeling with endurance training, these were typically conducted in healthy individuals under systemic regimens.²³ As summarized in Supplementary Table 1, preoperative exercise improves endothelial function, vein caliber, and grip strength, aiding AVF creation. In contrast, postoperative programs aim to maintain remodeling but often face reduced adherence due to pain or dialysis schedules.¹⁰ Supervised prehabilitation generally yields better compliance than postoperative regimens, emphasizing the benefit of structured support.²⁴ The variability in exercise type and duration across studies highlights the need for standardized protocols.²⁵ A combined pre- and postoperative strategy may optimize AVF maturation and long-term patency.

Adherence to the prescribed exercise regimen emerged as a critical factor influencing outcomes, similar to some prior studies.^15,26 This underscores the importance of patient education, motivation, and robust monitoring strategies when implementing preoperative programs suggested by the PINCH study (Supervised preoperative forearm exercise to increase blood vessel diameter) trial design,²⁷ to maximize compliance and, consequently, clinical benefit. Barriers to adherence in patients with ESKD, such as fatigue, comorbidities, and psychosocial factors, must also be addressed.²⁸ In our study, the patients with high adherence had mean AVF maturation nearly 2 weeks earlier than those with lower adherence and better flow. Although this difference did not reach conventional statistical significance, it is clinically meaningful, as earlier maturation may reduce the duration of dependence on temporary vascular access such as central venous catheters, which are associated with higher risks of infection and central venous stenosis. While better flow may result in better dialysis adequacy.

The primary AVF failure rate of 23.3% was within the range reported in the international literature (20-60%)^6,7 and compared favorably with some Indian data, where reported failure rates can vary.^26,29,30 Surveillance leads to increased intervention but may reduce long term AV failure rates. However, surveillance may lead to increased incidence of intervention in cases of non-significant stenosis of AVF. We did not follow AVF surveillance post operatively; this may have affected the AV failure rates as patients.

This study has several limitations. Its single-center, non-randomized design and small sample size limit generalizability and preclude causal inference. The lack of a control group makes it difficult to isolate the effect of exercise. Adherence was self-reported, introducing potential bias. Although measurements were done by a single sonographer, intraobserver variability cannot be ruled out. Data on dialysis adequacy and access recirculation were not collected.

Despite these limitations, our study provides valuable preliminary data from an Indian tertiary care setting, suggesting that preoperative upper limb exercises are feasible and potentially beneficial adjuncts for patients with ESKD awaiting AVF creation. These findings highlight the importance of patient adherence and suggest that even a relatively simple, low-cost intervention can positively influence the key vascular parameters.

Future research should focus on larger multicenter randomized controlled trials (RCTs) to confirm these benefits and delineate the optimal exercise prescription (type, intensity, duration, and frequency) and impact of adherence monitoring on AVF outcomes as well as dialysis adequacy.

This study suggests that a 6-week preoperative upper limb exercise program is feasible, well-tolerated, and can lead to a statistically significant increase in hand grip strength. It demonstrated a favorable trend in cephalic vein diameter enlargement. These findings support the potential utility of preoperative exercise as a low-cost, non-invasive intervention to optimize vascular conditions prior to AVF creation in patients with ESKD in India.