(1)
Department of Surgery, University of California, Davis, Sacramento, CA, USA
Abstract
Threatened or occluded access grafts are a frequent complication in patients undergoing hemodialysis and are associated with increased length of stay, morbidity, mortality, and hospital costs. An ideal access is one that can be reliably developed, delivers an optimal dialysis dose, and is resistant to thrombosis, infection, and the need for re-intervention. Access grafts generally have a greater likelihood to initial successful use and greater success for access salvage, but are prone to frequent failure and shorter long term patency. Arteriovenous fistula, however, are associated with lower likelihood to initial successful use, but have longer patency rates with fewer long term complications. When faced with a threatened graft and a secondary arteriovenous fistula is feasible, the best management approach may be an intervention to initially save the threatened graft but plans should be in place to perform a secondary arteriovenous fistula. If a secondary arteriovenous fistula is not performed prior to the third intervention to save the threatened graft, likelihood of a successful conversion to a secondary arteriovenous fistula decreases.
Keywords
Dialysis accessThrombosisStenosisTreatment of vascular access complicationsArteriovenous fistula maturationArteriovenous graftArteriovenous shuntClinical trialIntroduction
Over the past several years, the incidence of patients requiring hemodialysis has risen in accordance to the aging population and the incidence of diabetes. Since 2000, the adjusted ESRD incident rate in those aged 75 years and older has increased by 11 %, to 1744 patients per million individuals [1]. Moreover, survival of the very elderly patients who remain on hemodialysis more than 90 consecutive days is about 3 years [2]. A major challenge to maintain patients on hemodialysis is the construction and maintenance of the hemodialysis access site so that ongoing hemodialysis can continue until the end of the patient’s life.
The ideal vascular access for dialysis is one that allows dialysis for the longest period of time with fewest interventions, complications, and lowest costs. The National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) and the Fistula First Breakthrough Initiative (FFBI) have implemented clinical practice guidelines in an effort to maximize hemodialysis access longevity. A major goal of the FFBI was to have AV fistula prevalence of 66 % by 2009. By 2011, the US prevalent AVF rate was 57.9 % [3]. Unfortunately, in attempting to achieve the FFBI goals, there was an increase in AVF non-maturation rates of 20–50 % [4].
Presently, the NKF-KDOQI guidelines recommend an AV fistula in the wrist, followed by an elbow primary fistula [Recommendation 2.1] [5]. However, with the placement of a brachiocephalic or brachiobasilic arteriovenous fistula, the forearm is abandoned as an access site. Allon et al. propose the possible placement of a forearm AV loop graft with the cephalic or basilic vein as the outflow vein [6]. Hence a distal graft is placed in preference over a proximal (elbow) AV fistula. This approach decreases catheter days until a long term access is used and preserves the more distal anatomic site for access. This chapter addresses the decision analysis of treating patients with threatened or occluded access grafts with ongoing salvage techniques or constructing a new arteriovenous fistula site if one is available.
Search Strategy
A literature search of human subjects, English language publications published from 2008 to 2014 was used to identify published data on the treatment of threatened or occluded access grafts. Comprehensive databases searched were PubMed, Embase, and Cochrane Evidence Based Medicine. Terms used in the search alone or in combination included “dialysis access,” “thrombosis,” “stenosis,” “treatment of vascular access complications,” “arteriovenous fistula maturation,” “arteriovenous graft,” “arteriovenous shunt,” AND “clinical trial.” Articles were excluded if they did not specifically address dialysis access. All randomized control trials, cohort studies, guidelines, systematic reviews, and review articles pertaining to the treatment of threatened or occluded grafts were included in our analysis. We also used references from the articles we retrieved through our above query. The data was classified using the GRADE system (Table 38.1).
Table 38.1
Studies on access patency rates in patients on hemodialysis
P (Patients) | I (Intervention) | C (Comparator) | O (Outcomes) |
|---|---|---|---|
Patients with occluded or threatened Dialysis access grafts | Graft Salvage | Create a new vascular access at a new site | Primary patency, secondary patency, morbidity, cost |
Results
Society for Vascular Surgery Clinical Practice Guidelines
After the publication of the NFK-KDOQI Clinical Practice Guidelines, followed by the Fistula First Breakthrough Initiative (FFBI), Sidawy et al., published the Society for Vascular Surgery’s (SVS) clinical practice guidelines for the surgical placement and maintenance of arteriovenous hemodialysis access [7]. Within the SVS clinical practice guidelines, two recommendations deal specifically with threatened or occluded access grafts. “A plan and protocol for eventual conversion of forearm prosthetic access to a secondary autogenous AV access should be put in place at the presence of any sign of failing forearm prosthetic AV access, or after the first failure” (GRADE 2, very low-quality evidence) [8]. The rationale for this is to convert the prosthetic access mature outflow vein to an arteriovenous fistula, or to identify a new, remote site for arteriovenous fistula construction in a patient where the prosthetic access outflow vein is not deemed suitable. No high-quality evidence was found to support a strategy of converting prosthetic accesses with impending failure to secondary autogenous accesses, and these recommendations were based on very low-quality evidence consisting of unsystematic observations and the consensus of experts [8]. With respect to the management of a non-functional or failed arteriovenous access, the SVS guidelines recommend open surgery, endovascular therapy, or a combination of both to maintain or restore patency in AV access (GRADE 2, very low-quality evidence). Both open and endovascular interventions may add an average of 12 months of functionality with low morbidity and mortality while preserving future sites of access [8].
Arteriovenous Fistula Compared with Arteriovenous Graft
In our literature search, we attempted to find new evidence published after the 2008 SVS guidelines [7], that would address the specific question: In patients with threatened or occluded access grafts, is it better to salvage the graft, or create a new site? To date, no clinical trials have been performed to address such a specific question. However, there are a few studies that compared the patency of arteriovenous fistulas and grafts (Table 38.2), which we considered while developing our treatment recommendations.
Table 38.2
Studies evaluating patency in arteriovenous fistulas (AVF) and arteriovenous grafts (AVG)
Study | Number of patients | Type of dialysis access | Primary patency | Secondary patency | Cumulative patency | Dialysis catheter use | Quality of evidence |
|---|---|---|---|---|---|---|---|
Schild et al. (2008) [9] | 1700 | AVF vs. AVG | AVF: 10 % median patency AVG:10 % median patency | Moderate | |||
Slayden et al. (2008) [10] | Group 1 (40) Group 2 (108) | SAVF with protocol VS. SAVF with no protocol | Group 1: 82.5 % at 12 months, and 60.0 % at 24 months Group 2: 55.5 % at 12 months, and 50.5 % at 24 months | N/A | Group 1: 92.5 % at 12 months, and 87.5 % at 24 months Group 2: 94.4 % at 12 months, and 91.6 % at 24 months | Group 1: 22/40 (55 %) Group 2: data not available | Low |
Salman et al. (2009) [11] | 62 | SAVF type I VS. SAVF type II | SAVF type I: 87 % at 6 months, 14 % at 12 months SAVF type II: 71 % at 6 months, 11 % at 12 months | SAVF type I: 100 % at 12 months, 100 % at 24 months, and 83 % at 36 months SAVF type II: 92 % at 12 months, 88 % at 24 months, and 83 % at 36 months | N/A | SAVF type I: 21/35 (50 %) SAVF type II: 27/27 (100 %) | Low |
Woo et al. (2009) [12] | tAVF (190) AVG(168) | tAVF vs. AVG | tAVF: 48 % at 5 years AVG: 14 % at 45 years | tAVF: 57 % at 5 years AVG: 19 % at 45 years | Low
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