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Author Topic: Exercise, cannulation and AVF maturation
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Post Exercise, cannulation and AVF maturation
on: January 16, 2012, 02:45
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A colleage teach our patients that exercise and repetitive one side (usually venous or outflow) cannulation could help to achieve maturation of certain AVF well beyond 4 months after surgery, even without visible vessel, barely heard bruit or palpable thrill. I dont think this to be true. Comments?

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Post Re: Exercise, cannulation and AVF maturation
on: January 16, 2012, 10:29
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An interesting question.

There is a lot of interest in the effects of exercise and AVF maturation. No clear evidence to prove or reject the concept.
Depends when the patient performs these hand grip exercises - before or after AVF creation.

Belief: Hand grip exercise can help with the maturation process
Evidence is available through small case studies regarding benefits of hand grip exercise in CKD 4 and 5,
before creating an AVF by increasing blood flow and vessel diameter which potentially may improve the chance of AVF maturation.

I have included two abstracts below supporting this belief:

http://journals.lww.com/amjmedsci/Abstract/2003/03000/Isometric_Exercise_Increases_the_Size_of_Forearm.3.aspx

http://onlinelibrary.wiley.com/doi/10.1002/bjs.7004/full

A common mistake made by clinicians is waiting eternally for an AVF to mature and relying on hand grip exercise to do wonders.
Two reasons for this approach -
1) reluctance to accept that the AVF has failed and intervention is needed and
2) Easy alternative - a tunneled catheter is in place so patient continues to receive hemodialysis and reluctance to change the status quo

As yet no clear evidence is available for benefits of hand grip exercise after creating an AVF.
A prospective study is underway

http://clinicaltrials.gov/ct2/show/NCT01061008

and hopefully we will soon have a better understanding.

Drawback - prolonged use of tunneled catheter and its associated ill effects (infection, sepsis, central vein stenosis, inadequate dialysis).

Ideally, if the AVF fails to show signs of maturing in 6-8 weeks,
one needs to evaluate with either a fistulogram or at least a doppler US and intervene to assist with the maturation process.
Waiting beyond 12 weeks is often detrimental to the patient and one should 'bite the bullet' and plan for another access.
Sooner this decision is made, shorter will be the duration of tunneled catheter.
Certainly, if the AVF with barely heard bruit or palpable thrill after 6-8 weeks, is very unlikely to mature to provide adequate flows.
A minimum of 300-350 ml/min is what we practice in USA.
Outside USA, flows in the 250-300 range are used but with longer duration.

As far as one needle cannulation:
again it is more of patient safety rather than assisting with maturation process.
If the AVF examination reveals a marginally matured AVF, using single needle initially may limit the hematoma in the event there is infiltration compared to two needles.
Also gives an opportunity to the dialysis staff to define the anatomy of the outflow vein.

A long answer to a short question, but I think a very relevant discussion in the big scheme of getting more AVFs.

Tushar Vachharajani MD
Chief
Division of Nephrology and Hypertension
Salisbury VAMC
Salisbury, NC

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