Primary Fistula Failure

Optimizing vascular access outcomes remains an ongoing challenge for the renal community¹. The arteriovenous fistula (AVF) is widely recognized as the access of choice because of greater reliability, fewer complications, reduced infections, fewer events that require hospitalization and decreased mortality².

The major complication with AVF is the high frequency of primary failure or suitability failure due to early thrombosis or lack of maturation^3,4,5. Primary AVF failure is reported to occur after AVF placement in up to 40% cases^3,4,5. A review of current published literature demonstrates variability in the definition of primary failure³. Some investigational studies define primary failure as the inability to use the access successfully for dialysis; others define primary failure as unsuccessful fistula utilization for at least 6 consecutive dialysis sessions^3,5. This difference in definitions makes comparisons between the many published reports more difficult. The renal community is currently attempting to establish standardized, objective and accurate criteria for primary failure³.

There are many factors associated with the high rate of primary AVF failure. The dialysis population is growing exponentially with older patients and a higher proportion of diabetes and other comorbidities. Multiple studies have confirmed that older age, coronary artery disease (CAD) and peripheral vascular disease (PVD) are clinical indicators associated with an increased risk for AVF failure^1,6,7 . This makes pathophysiologic sense because adequate inflow and outflow are required for AVF maturation and would be hampered by diseased vasculature represented by atherosclerosis and arteriosclerosis⁶. However, in a recent study by Maya et al., that compared the clinical outcomes of brachiocephalic fistulae, transposed brachiobasilic fistulae and AV grafts; only patient gender and access type predicted primary access failure. In multiple variable logistic regression analysis including access type, patient age, sex, diabetes, CAD, PVD, cerebrovascular disease, and prior access, primary access failure was lower in males than in females (HR 0.54; 95%CI, 0.38 to 0.78, p=0.0001)⁵. Additionally, primary access failure was higher for brachiocephalic versus transposed brachiobasilic fistulae (HR 2.76; 95% CI, 0.38 to 1.57 p=0.48). These results must be interpreted with caution due to study limitations including its retrospective, observational design and single dialysis center experience. Further prospective studies are necessary to further elucidate the factors that predict primary failure of brachiocephalic fistulae and the potential advantages and disadvantages of the more complex surgery required to create a transposed brachiobasilic fistula⁵.

The etiology of AVF primary failure is not limited to pathophysiologic processes. Public healthcare policy, practitioner training, available interventions and patient education all contribute to the success of a functioning fistula. Worldwide initiatives have demonstrated the potential beneficial impact of public policy on improving outcomes and decreasing costs⁸. Fistula First, a collaboration involving a national consortium of 35 public and private organizations including providers, payers and patients, has been a catalyst for promoting practitioner and patient training through 11 change concepts.

Below are the 11 change concepts for increasing the prevalence of AV fistulas for hemodialysis as noted on www.fistulafirst.org

1. Routine CQI Review of Vascular Access
2. Timely Referral to Nephrologist
3. Early Referral to Surgeon for "AVF Only" Evaluation and Timely Placement
4. Surgeon Selection Based on Best Outcomes, Willingness, and Ability to Provide Access Services
5. Full Range of Appropriate Surgical Approaches to AVF Evaluation and Placement
6. Secondary AVF Placement in Patients with AV Grafts
7. AVF Placement in Patients with Catheters Where Indicated
8. AV Fistulas Cannulation Resources for Staff
9. Monitoring and Maintenance to Ensure Adequate Access Function
10. Education for Care Givers and Patients
11. Outcomes Feedback to Guide Practice

The success of change concepts 2 and 3, timely referral to a nephrologist and early referral to a surgeon respectively, has been demonstrated in numerous studies. One group reported that 73% of their patients initiated hemodialysis (HD) with AVF and only 23% with a catheter when seen by a nephrologist greater than three months prior to beginning HD⁸. Literature review indicates that with early referral to a surgeon and consequent preoperative vessel mapping, some type of fistula can be placed in up to 75% of patients¹.

An adequate timeframe in which to complete pre-ESRD care and education and obtain pre-operative vascular mapping is essential for optimal timing and successful access placement¹. Several studies have demonstrated the efficacy of preoperative vascular mapping to improve AVF patency rates when compared with preceding experience in which vascular mapping was not employed^9,10,11. The impact of routine preoperative vascular mapping on the type and outcomes of vascular access placement was evaluated in a recent prospective study. Vascular mapping resulted in an increase in the proportion of fistulae placed from 34 to 64% (p< 0.001) and significant improvement in primary patency. Initial adequacy, in a subset of forearm fistulae, increased substantially from 34 to 54% (p=0.06) with the greatest improvement noted among women and diabetics¹¹.

Change concept 4: Surgeon selection based on best outcomes, willingness, and ability to provide access services is reinforced by studies confirming that surgical training is paramount to both fistula placement and survival^12,13. Analysis of the Dialysis Outcomes and Practice Patterns Study notes that risk of primary fistula failure was 34% lower (relative risk = 0.66, p = 0.002) when placed by surgeons who created >25 (vs. < 25) fistulae during training. Continuing strategies to enhance surgical training in fistula creation is crucial for decreasing primary fistula failure^12,13. Finally, the benefits of change concept 8, cannulation training for AVF, are evident in studies that show experienced nurses are able to predict AVF maturity 80% of the time⁶.

These examples are strong evidence of the success of medical management and program structure to decrease primary fistula failure and improve patient outcomes⁸.

References

1. Allon M. Current management of vascular access. Clin J Am Soc Nephrol 2:786-800, 2007
2. Schon D, Blume SW, Niebauer K, Hollenbeak CS, de Lissovoy G. Increasing the use of arteriovenous fistula in hemodialysis: Economic benefits and economic barriers. Clin J Am Soc Nephrol 2:286-276, 2007
3. Ravani P, Spergel LM, Asif A, Roy-Chaudhury P, Besarab A. Clinical Epidemiology of arteriovenous fistula in 2007. J Nephrol 20:141-149,2007
4. Maya ID and Allon M. Vascular access:Core curriculum 2008. Am J Kid Dis 51:702-708, 2008
5. Maya ID, O’Neal JC, Young CJ, Barker-Finkel J, Allon M. Outcomes of brachiocephalic fistulas, transposed brachiobasilic fistulas, and upper arm grafts. Clin J Am Soc Nephrol 4:86-92, 2009
6. Lok CE. Fistula First intiative: Advantages and pitfalls. Clin J Am Soc Nephrol 2:1043-1053, 2007.
7. Lok CE, Allon M, Moist LM, Oliver MJ, Shah H, Zimmerman D. Risk equation determining unsuccessful cannulation events and failure to maturation in arteriovenous fistula (REDUCE FTM I). J Am Soc Nephrol 17: 3204-3212, 2006
8. Sands, JJ. Vascular access: The past, present and future. Blood Purif 27:22-27, 2009
9. Silva MB Jr, Hobson RW, Pappas PJ, Jamil Z, Araki CT, Goldberg MC, Gwertzman G, Padberg FT Jr. A strategy for increasing use of autogenoushemodialysis access procedures: impact of preoperative noninvasive evaluation. J Vasc Surg 27:302–307, 1998
10. Huber TS, Ozaki CK, Flynn TC, Lee WA, Berceli SA, Hirneise CM, Carlton LM, Carter JW, Ross EA, Seeger JM. Prospective validation of an algorithm to maximize native arteriovenous fistulae for chronic hemodialysis access. J Vasc Surg 36:452–459, 2002
11. Allon M, Lockhart ME, Lilly RZ, Gallichio MH, YoungCJ , Barker J, Deierhoi MH, Robbin ML. Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients. Kidney Int 60:2013–2020, 2001
12. Saran R, Elder SJ, Goodkin DA, Akiba T, Ethier J, Rayner HC, Saito A, Young EW, Gillespie BW, Merion RM, Pisoni RL. Enhanced training in vascular access creation predicts arteriovenous fistula placement and patency in hemodialysis patients: Results from the Dialysis Outcomes and Practice Patterns Study. Ann Surg 247:885- 891, 2008
13. O'Hare AM, Dudley RA, Hynes DM, McCulloch CE, Navarro D, Colin P, Stroupe K, Rapp J, Johansen KL. Impact of surgeon and surgical center characteristics on choice of permanent vascular access. Kidney Int 64:681-689, 2003

P/N 101050-01 Rev.00 3/2009