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New approach needed to evaluate vascular access options
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When it comes to selecting a vascular access type for a patient with late-stage CKD or ESKD, the arteriovenous fistula, once labelled the ‘gold standard’ for creating permanent access, may not always be the ideal one, according to a viewpoint published in the Clinical Journal of the American Society of Nephrology.
Michael Allon, MD, nephrologist at University of Alabama at Birmingham (UAB), wrote that “key assumptions and recommendations in the 2006 Kidney Disease Outcomes Quality Initiative vascular access guidelines ... are not relevant to the contemporary United States hemodialysis population.” As a member of the division of nephrology at UAB, Allon helped guide recent updates to the KDOQI vascular access guidelines, which will be presented at the National Kidney Foundation’s Spring Clinical Meetings in Boston next month.
Challenging the AVF
The accepted view in the kidney community – and verified in the 2006 guidelines – has been that the natural, arteriovenous fistula (AVF) is superior to the synthetic arteriovenous graft (AVG) based on better secondary survival and lower frequency of interventions and infections. “However, intent-to-treat analyses that incorporate the higher primary failure of AVFs demonstrate equivalent secondary survival of both access types,” Allon wrote. “Moreover, the lower rate of AVF versus AVG infections is counter balanced by the higher rate of catheter-related blood stream infections before AVF maturation,” he said, referring to the use of temporary central venous catheters (CVCs) to initiate dialysis while the fistula matures.
“In addition, AVFs with assisted maturation (interventions before successful AVF use), which account for about 50% of new AVFs, are associated with inferior secondary patency compared with AVGs without intervention before successful use.”
CVCs for compromised patients
A lack of AVF maturation means a higher rate of CVC dependence, Allon reported. Previous reports that provided research for the original KDOQI guidelines observed AVF nonmaturation in only 10% of patients.
“More recent publications, reflecting widespread AVF creation in the great majority of patients on dialysis, have reported substantially higher (30%–60%) AVF nonmaturation rates,” Allon wrote.
CVC use is believed to result in excess mortality in patients on hemodialysis, “however, recent data suggest that CVC use is simply a surrogate marker of sicker patients who are more likely to die, rather than being a mediator of mortality,” Allon wrote. “The challenge in comparing patient survival between patients who do or do not undergo AVF creation, is that there are important differences not easily captured in administrative databases. If a patient with advanced CKD is perceived by the nephrologist or surgeon to have a reasonable life span, it is likely that an AVF will be placed promptly.
“In contrast,” Allon said, “if the patient has a poor functional status or limited life expectancy, the physician is more likely to postpone AVF creation until after the patient starts hemodialysis ... (T)he association between starting hemodialysis with a CVC and dying is confounded by their age. Similarly, a high comorbidity or poor functional status confound the association between CVC use and patient mortality.”
Ultimately, Allon said, data released since the 2006 KDOQI vascular access guidelines were released “should be incorporated to re-inform current decision making about vascular access.”
Disclosure: Allon is supported by grant 1R21DK104248-01A1 from the National Institute of Diabetes, Digestive and Kidney Diseases, and reports personal fees from CorMedix.
Perspective
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Deborah Brouwer-Maier, RN
It is difficult as a nurse in the kidney care field with a strong interest in improving vascular access care to see the “march of time” on the arteriovenous fistula as the best access for patients on dialysis. I have devoted many hours of volunteerism to support the previous body of work reflected in the 2006 KDOQI guidelines on vascular access, as cited by Allon in his paper.
I think the Fistula First name did much damage, as people heard it and misconstrued that the campaign, started 15 years ago in April 2004 as a CMS recommended practice, has been focused on making the AVF the right choice for all patients. The intention was to consider an AVF first as part of the individualization of access selection and then defer to an AVG if the AVF is not a suitable option. In fact, AVG material has improved to allow for early cannulation and it clearly is a better choice in efforts to avoid a catheter.
Yes, AVF failure-to-mature rates are unacceptable high. We still don’t understand the root cause of the high failure-to-mature rates. I do strongly believe our surgical technique has not properly and fully be studied. The surgeons who are specialized and have a high volume of AVF cases can achieve much lower failure-to-mature rates. The fistula maturation studies did not review the variation in surgical technique, anesthesia methods or even the skill set of the surgeons. Most surgeons in the United States had less than 10 AVF cases in their training when they started placing AVFs. I watched U.K. surgeons in training reach 100 cases before they could solo for an AVF creation. Skills must be mastered to improve access outcomes.
Our practice patterns also push the need for high flow access. Many lower arm AVFs do reach maturity, but in the U.S. don’t meet the size requirements due to the high blood flow rates we use to do rapid dialysis. We also don’t use the new plastic cannula devices in place of the traditional AVF needles.
I do agree the new early AVG materials may be a very good choice for the patient with a limited life expectancy, as it can avoid a catheter and will most likely last 2 years. I also recommend the lower arm loop graft, so the upper arm is preserved for a future access. This approach is like the new Life Plan – old idea of the patient plan of care including access modality changes with the best access choice for each modality.
Catheter care has also greatly improved with new ways to decrease infection rates. A big concern is if the revised KDOQI guidelines moves to make catheters an acceptable life plan for access choice, how will we care for them in the U.S.? We have a larger proportion of patient care nephrology technicians and in many states, they are limited by the nursing scope of practice to initiate or terminate dialysis with a catheter.
Fistula First (various work groups)
Vascular Access Marketing Manger
Transonic Inc.
Ithaca, NY
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