Isometric Preoperative Exercise on Autologous Arteriovenous Fistulas. Randomized Clinical Trial
Condition: Arteriovenous Fistula Thrombosis; Arteriovenous Fistula Stenosis
MeSH terms: Thrombosis; Arteriovenous Fistula; Fistula
Study type: Interventional

Summary: 
      A good vascular access (VA) is vital for hemodialysis (HD) patients. The start of HD with
      autologous arteriovenous fistula (AVF) means higher survival, lower sanitary costs and
      complications. The distal forearm AVF is known as the best option but not all patients are
      good candidates for this surgery, and there is a primary failure rate between 20 and 50%
      published in literature.

      The choice of the optimal AVF for each patient is conditioned mainly by the anatomical and
      hemodynamic characteristics of the artery and the vein chosen to perform the anastomosis.
      These characteristics can be modified by performing physical exercise Some vascular access
      guidelines suggest the performance of isometric exercises in the pre and postoperative period
      of the AVF confection. However, there is very little data in literature on the possible
      efficacy of preoperative exercise, although small published observational studies point to an
      improvement in the venous and arterial caliber. Regarding the postoperative exercises, they
      do seem to improve maturation, however the degree of evidence in literature is low and there
      is no consensus on the exercise protocol to follow.

      We present an open-label, multicenter, prospective, controlled and randomized study in order
      to evaluate the usefulness of preoperative isometric exercise (PIE) in pre-dialysis patients
      or in prevalent HD with indication of performing a new AVF. The randomization will be 1: 1,
      one group of patients will perform PIE for 8 weeks and the other group of patients will be a
      control group. The main purpose will be to evaluate if there is a lower rate of primary
      failure in the PIE group compared with control group.
    

Detailed description: 
      RECRUITING PERIOD: 20 months.

      FOLLOW UP: From the first preoperative assessment visit for AVF up to 3 months after its
      creation.

      METHODS:

      After signing the informed consent, patients will be randomized through a centralized
      computer program to one of two groups of patients, PIE group versus control group.

      In both groups of patients, a first physical examination of upper arm extremities and an
      initial doppler ultrasound will be performed, evaluating the anatomical and hemodynamic
      characteristics of the arteries and veins of both arms. At that time, a first surgical option
      of AVF will be indicated.

      In the PIE group, the patients will receive detailed information about the daily preoperative
      exercise protocol and they will perform this protocol for at least six and ideally more than
      eight weeks based on:

        -  Isometric exercise using hand-grip. This exercise consists of two sets of 30 hand-grip
           contractions with the hand of the upper arm candidate for AVF (in case of doubts about
           the most appropriate arm for AVF the exercise will be performed with both arms). The
           patient will rest one minute every 10 contractions and 5 minutes between both sets. The
           patient will repeat this protocol twice a day, morning and night (Approximately 15
           minutes each session). The contraction intensity will start with half of the maximum
           force obtained by dynamometry and will be increased or decreased to be placed on an
           effort intensity 2-3 in the Borg scale.

        -  Isometric exercise using elastic bands. At noon the patient will perform a slow
           contraction session using elastic band with 20 slow repetitions with the arm in flexion
           and 20 repetitions with the arm in extension. (Total duration: less than 10 minutes)
           Clinical follow-up of these patients will be fortnightly to ensure that they perform the
           exercises correctly and to measure the force acquired through dynamometry. Likewise,
           brachial diameter and bicipital and tricipital skinfolds will be measured. In addition,
           they will be contacted by telephone once a week to assess compliance. Doppler
           ultrasonography will be performed at the initial visit, and at 4 and 8 week-visits
           (visits 1, 2 and 3). In the doppler ultrasound performed at 8 weeks, the final surgical
           indication will be given depending on the caliber of the vessels in the chosen arm. At
           the initial visit and at the 8-week visit, biological samples will be obtained to assess
           the parameters of nutrition and muscle mass and a bioimpedanciometry will be performed.

      The date of surgery will be coordinated with anesthesia and peripheral vascular surgery
      services to program the intervention during the fortnight after the 8-week isometric exercise
      period (weeks 9-10). In prevalent HD patients with central venous catheter (CVC) presenting
      greater urgency of AVF, surgery will be scheduled between the 6 and 8 week of exercises.

      Control group patients will follow the usual surgical waiting list protocol (Estimated 1,5-2
      months). Baseline and preoperative ultrasonography will also be performed in these patients,
      in which it will be verified that there are no significant changes in vascular mapping
      (punctures sites, hematomas, etc.) and the indication of AVF performed in the initial visit
      will be confirmed. Dynamometry, bicipital and tricipital skinfolds measurement, brachial
      diameter, analytical parameters of nutrition and muscle mass and bioimpedanciometry will be
      performed both at the onset visit and at the preoperative visit. The only difference with PIE
      group is the 4 weeks follow-up ultrasound that will not be performed in control group.

      After the AVF creation the maturation will be monitored with doppler ultrasound at 1, 6 and
      12 weeks after the surgery (visits 4, 5 and 6) and the usual postoperative isometric exercise
      with ball contraction will be recommended to all patients. Follow-up will be completed three
      months after the surgical procedure, defining whether the AVF has matured or if there has
      been a primary failure.

      FOLLOW-UP LOSSES:

        -  Abandonment or withdrawal of informed consent.

        -  Transplant.

        -  Change of dialysis technique.

        -  Transfer to another center.

        -  Exitus.
    

Intervention name(s): Isometric exercises using Hand grip and elastic bands
Intervention type(s): Device
Intervention description(s): Isometric exercises using hand-grip. This exercise consists of two sets of 30 hand-grip contractions with the hand of the upper arm candidate for AVF (in case of doubts about the most appropriate arm for AVF the exercise will be performed with both arms). The patient will rest one minute every 10 contractions and 5 minutes between both sets. The patient will repeat this protocol twice a day, morning and night (Approximately 15 minutes each session). The contraction intensity will start with half of the maximum force obtained by dynamometry and will be increased or decreased to be placed on an effort intensity 2-3 in the Borg scale.
Isometric exercise using elastic bands. At noon the patient will perform a slow contraction session using elastic band with 20 slow repetitions with the arm in flexion and 20 repetitions with the arm in extension. (Total duration: less than 10 minutes)
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Open-label, prospective, controlled, randomized, multicenter study in parallel groups, where in the preoperative AVF period, one group of patients will perform an isometric exercise protocol for 8 weeks and will be compared with a control group of patients that will not perform this preoperative exercise
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: doppler ultrasound; physical exercise; arteriovenous fistula maturation