NKF K/DOQI GUIDELINES 2000
 
 

GUIDELINES FOR VASCULAR ACCESS

VI. Potential Quality of Care Standards

BACKGROUND

Hemodialysis access failure is a major cause of morbidity for patients on hemodialysis. A high percentage of hospitalizations in these patients is due to vascular access complications.9-11,194 Results appear to be worsening, since the interval between access placement and the need for a procedure to restore access patency has been decreasing.7,10 In addition, expenditures for reconstituting patency are substantial and increasing.7,10

To reverse these trends, dialysis centers should:

A. Institute monitoring programs to detect vascular accesses at risk.

B. Establish quality assurance programs that track access complication rates and outcomes.

C. Develop methods that extend access use-life.

Access use-life can be extended by:

A. Increasing the percentage of patients with native or primary AV fistulae through:

1. Early identification and referral of patients with progressive kidney disease to nephrologists–allowing access construction well in advance of the need for hemodialysis (Evidence)

2. Re-evaluation for a native AV fistula after every access failure (Opinion)

B. Periodic monitoring of accesses to detect hemodynamically significant stenoses prior to thrombosis (Evidence)

C. Expeditious referral of patients for appropriate angioplasty or surgical revision following the detection of stenoses (Evidence)

D. Implementing staff and patient education programs on the importance and care of vascular access (Opinion)

GUIDELINE 29

Goals of Access Placement–Maximizing Primary AV Fistulae

A. Primary AV fistulae should be constructed in at least 50% of all new kidney failure patients electing to receive hemodialysis as their initial form of renal replacement therapy. Ultimately, 40% of prevalent patients should have a native AV fistula (see Guideline 3: Selection of Permanent Vascular Access and Order of Preference for Placement of AV Fistulae.) (Opinion)

B. Patients should be re-evaluated for possible construction of a primary AV fistula after failure of every dialysis AV access. (Opinion)

C. Each center should establish a database to track the types of accesses created and the complication rates. (Opinion)

Rationale A primary AV fistula using the cephalic vein confers the best permanent access with the fewest complications13,38,40,41,195 (see Guideline 3: Selection of Permanent Vascular Access and Order of Preference for Placement of AV Fistulae). Native accesses have the best 4- to 5-year patency rates and require fewer interventions compared to other access types.3,4 The frequency of primary AV fistula construction in the US is unjustifiably low (less than 30% to total access placements)194 compared to Europe or Canada (with frequencies of more than 50% of total access placements),3,196 even after adjustments are made for demographic differences that may influence choice of access type. An increase in the percentage of native AV fistulae is best accomplished by early determination of the patient’s preferred dialysis modality while dialysis initiation is still months away, since primary AV fistulae ideally should be allowed to mature 3 to 4 months before use. In many patients, a previous native or synthetic access produces dilatation of arm veins, permitting construction of a new primary AV access at a site not previously available. AV fistula constructions that use the brachial artery can produce long-lasting access.41,44,46,47,195 Time-urgency for initiating hemodialysis does not justify substitution of a synthetic dialysis AV graft in patients starting hemodialysis or in patients with failed previous accesses because, in either case, cuffed catheters are an effective means of bridging the longer time necessary for primary AV fistula maturation.70,72,75,197

Each center should develop an access database in order to identify problems in access creation and maintenance.

GUIDELINE 30

Goals of Access Placement–Use of Catheters for Chronic Dialysis

A. Less than 10% of chronic maintenance hemodialysis patients should be maintained on catheters as their permanent chronic dialysis access. In this context, chronic catheter access is defined as the use of a dialysis catheter for more than 3 months in the absence of a maturing permanent access. (Opinion)

B. ESRD patients should be educated on the risks and benefits associated with catheters and strongly encouraged to allow the creation of an AV fistula for permanent access where appropriate. (Opinion)

Rationale The use of cuffed dialysis catheters for long-term access is associated with a dramatic increase in access complications:

A. Cuffed catheters are associated with lower blood flow rates compared to AV access.72,84,93,197 As a result, catheters used long-term without appropriate adjustments in treatment duration can compromise dialysis adequacy.198 Compromise of dialysis adequacy is associated with increased morbidity and mortality.

B. Systemic and local infections occur more frequently with cuffed catheters75,78,93, 139,153,197,199-201 than with AV accesses.136

C. Chronic catheter access is associated with a risk of central venous stenosis.20,26,102 Development of central vein stenosis can preclude the establishment of a permanent vascular access for hemodialysis.

D. The initial success, ease-of-use, and painless access to the patient’s blood offered with a dialysis catheter may foster reluctance in the patient to consider other more permanent access options, despite the greater risk of infection and inadequate dialysis associated with chronic permanent catheter access use. Patients should be educated on these issues and strongly encouraged to allow creation of an AV fistula for permanent access where appropriate.

GUIDELINE 31

Center-Specific Thrombosis Rate

A. The rate of graft thrombosis should not exceed 0.5 thrombotic episodes per patient year at risk. (Evidence/Opinion)

B. After adjusting for initial failures (ie, failures within the first 2 months of fistula use), the rate of thrombosis of native AV fistulae should be less than 0.25 episodes per patient year at risk. (Opinion)

C. Dialysis centers should examine their thrombosis rates and the underlying causes as part of an ongoing QA/CQI program. (Opinion)

Rationale The current national average rate of thrombosis of dialysis AV grafts is unknown, but is likely to be higher than the overall rate (all permanent accesses) of approximately 0.8 episodes per patient year at risk,9,119 since these results included all types of permanent AV access. Some centers have reported much higher thrombosis rates,29,164 but such rates are quite sensitive to the mix of native and prosthetic grafts in the dialysis center and vascular comorbidity. The rate of thrombosis is largely determined by the presence of unrecognized hemodynamically significant stenosis.29,114,160,161,163,202 Early detection and treatment of stenosis reduces the frequency of thrombosis9,29,119,203 and reduces access replacement rates by up to 70%.9,119 Dialysis AV grafts should be monitored to permit early detection of hemodynamically significant stenosis with the goal of reducing the thrombosis rate to a maximum of 0.5 thrombosis per year for AV grafts. Based on intervention studies,9,119 this thrombosis rate is achievable. By detecting and treating stenoses early in patients with synthetic grafts, as outlined in this set of guidelines, the Work Group believes that the rate of graft thrombosis can be reduced significantly.

Native accesses have a much lower thrombosis rate compared to prosthetic grafts.4 Sequential measurements of flow can detect deterioration of native access function.165 All of these strategies should reduce the risk of thrombotic failure. The Work Group concluded that a thrombosis rate of 0.25 episodes per patient year in native fistulae is achievable.

GUIDELINE 32

Infection Rate

The rate of infection should not exceed 1% in primary AV fistulae and should not exceed 10% in dialysis AV grafts, both calculated over the use-life of the access. (Opinion)

For tunneled cuffed catheters, the recommended target rate of systemic infection is less than 10% at 3 months and less than 50% at 1 year. (Opinion)

Rationale Infectious complications of accesses are a leading cause of morbidity and mortality in dialysis patients.194 The current national combined infection rates for permanent accesses, for local and bacteremic infections, are 1% to 4% for primary AV fistulae40,41,47 and 11% to 20% for AV grafts.14,40,51,53,58,192,204

The catheter infection rate is highly variable151,190 and clearly depends on the duration of use.78,99,153 At 2 weeks of catheterization, the incidence of infection of noncuffed central catheters is generally under 8%.205 Suchoki et al78 reported a <5% bacteremia rate in cuffed catheters used <3 months. In contrast, a 50% removal rate for infection was reported for cuffed catheters at 12 months of use.78

The Work Group’s recommendations are significantly lower than the published experiences of various centers. The Work Group believes infection rates can be significantly lowered through meticulous attention to detail, and in the case of catheters, following the recommendations in Guideline 15: Catheter Care and Accessing the Patient’s Circulation, on skin preparation at the time of placement,206 topical antibiotics,150,151 and the use of non-occlusive dressings.149 Programs with high infection rates should consider the importance of nurse and patient training140 (see Guideline 13: Infection Control Measures).

GUIDELINE 33

Primary Access Failure Rate–AV Grafts

The primary access failure rates of virgin dialysis AV grafts in the following locations and configurations should not be more than: (Evidence/Opinion)

Forearm straight grafts: 15%

Forearm loop grafts: 10%

Upper arm grafts: 5%

By proposing these goals for 30-day primary failure rates for various graft configurations, the Work Group does not wish to imply that upper arm grafts should be elected over forearm grafts solely on the basis of these recommended primary failure rates. Indeed, the Work Group encourages the creation and maintenance of access sites as distally as possible to preserve more proximal veins for future access options.

Each center should monitor its performance to identify problems in access construction and use. (Opinion)

Rationale Primary access failure is considered failure of patency within the first 30 days after placement. Primary failure of dialysis AV grafts is caused by technical problems. It is the Work Group’s opinion that the primary failure rate reflects a center effect that is influenced by surgical access construction, patient demographics, comorbidity, and graft loss due to premature cannulation and hematoma formation. Primary failure rates of dialysis AV grafts at the same anatomical sites vary depending on whether the grafts are the primary, secondary, or tertiary access. The rates provided are derived from the published literature for first graft accesses constructed in a general hemodialysis population.13,14,38,40,51,53 Failure of a dialysis AV graft prior to use reflects surgical construction problems. Prosthetic bridge graft survival is decreased in diabetics, even at 30 days, and may be affected adversely by increasing age in non-diabetics.198 Patient demographics, characteristics, and comorbidity may differ across centers and explain some of the center effect. Each center should monitor its performance, recognizing the influence of some demographic factors, but tracking its own problems in access construction and use. Marked deviations from the recommended patency rate should invoke a multidisciplinary evaluation of possible factors and their modification.

GUIDELINE 34

Primary Access Failure Rate–Tunneled Cuffed Catheters

The primary failure rate of catheters refers to the fraction of catheters that are unable to deliver adequate blood flow (>300 mL/min) during the first attempted dialysis treatment.

The primary failure rate of tunneled cuffed catheters should be no more than 5%. The cumulative incidence of the following insertion complications should not exceed 2% of all catheter placements: (Evidence)

A. Pneumothorax requiring a chest tube

B. Symptomatic air embolism

C. Hemothorax

D. Hemomediastinum

E. Hematoma requiring evacuation

Rationale Complications related to the insertion of tunneled cuffed catheters depend on operator skill. Cuffed catheters can be inserted with reference to anatomical landmarks, with or without ultrasound,190,207 but always with the use of fluoroscopy to verify proper positioning of the catheter tip. Cuffed catheters can be placed by nephrologists, surgeons, or radiologists.190 Cumulative complication rates of less than 5% are routinely obtained.73,190 A recommended complication rate of less than 2% is lower than values reported in the literature. However, the published results are based on procedures obtained without benefit of ultrasound guidance. In the Work Group’s opinion, rates of 2% are obtainable in many centers and should be the goal.

GUIDELINE 35

Primary Access Failure–Native AV Fistulae

No guideline for primary access failure is recommended. (Opinion)

Rationale To achieve the proposed goal of attaining native AV fistulae in at least 40% of patients requiring dialysis access (see Guideline 29: Goals of Access Placement–Maximizing Primary AV Fistulae), the Work Group recommends that the primary failure rate of AV fistulae not be used as an indicator of quality. To do otherwise might discourage native fistulae construction in patients with more complex vascular anatomy (ie, in patients who are at a higher risk for failure). Nevertheless, primary failure of native AV fistulae should be examined in dialysis centers as part of their QA/CQI vascular access programs.

GUIDELINE 36

Cumulative Patency Rate of Dialysis AV Grafts

The cumulative patency rate of dialysis AV grafts refers to the number of grafts that remain patent (regardless of the number of primary interventions and/or thrombectomies) during the given time period.

The cumulative patency rate of all dialysis AV grafts should be at least 70% at 1 year, 60% at 2 years, and 50% at 3 years. (Evidence/Opinion)

Rationale Numerous investigators report 1-year patency rates of AV grafts between 63% and 90%.13,14,38,184 Mehta reports an overall average patency rate of 70%.4 Many investigators have reported patency rates at 2 and 3 years as well.13,14,38,43 Outflow obstruction, followed by thrombosis, accounts for the majority of AV graft failures. The Work Group believes that prospective monitoring (see Guideline 10: Monitoring Dialysis AV Grafts for Stenosis, and Guideline 11: Monitoring Primary AV Fistulae for Stenosis) can improve this reported experience despite the aging of the population and the increasing percentage of patients with diabetes or peripheral vascular disease. Thus, the cumulative patency targets for AV grafts of 70% at 1 year, 60% at 2 years, and 50% at 3 years should be achievable.

GUIDELINE 37

Cumulative Patency Rate of Tunneled Cuffed Catheters

Because of variations in catheter use and design, the Work Group believes that it cannot make a reasonable estimate of expected cumulative patency of dialysis catheters at this time. The use of cuffed catheters as permanent vascular access should be discouraged except in particular patient groups (see Guideline 3: Selection of Permanent Vascular Access and Order of Preference for Placement of AV Fistulae). (Evidence/Opinion)

Rationale Intravenous double-lumen cuffed catheters are used both as temporary access while a permanent access is maturing and as permanent access in patients who have exhausted other options. This variation in intended use creates significant variation in catheter survival rates. Moss reported a median cumulative catheter survival rate of 18.5 months; 65% of silicone dual-lumen catheters survived 1 year.73 By contrast, Lund et al190 reported a 1-year cumulative patency of 30%. Canaud et al,74 using two single-lumen silastic catheters (with the majority serving to bridge a period until permanent access was established), reported an average catheter survival of 57 days. Suchoki et al78 reported a 50% catheter survival rate at 12.7 months.

The Work Group discourages the use of cuffed catheters as permanent vascular access because of their increased complication rates. The primary reason for cuffed catheter loss is infection.78

GUIDELINE 38

Cumulative Patency Rate of Primary AV Fistulae

No guideline for cumulative access patency is recommended. (Opinion)

Rationale To achieve the proposed goal of attaining native AV fistulae in at least 40% of patients requiring dialysis access, the Work Group recommends that the cumulative patency rate of AV fistulae not be used as an indicator of quality. To do otherwise might discourage native fistulae construction in patients with more complex vascular anatomy who may be at a higher risk for failure. Nevertheless, cumulative patency rates should be examined in dialysis centers as part of their QA/CQI vascular access programs.

© 2001 National Kidney Foundation, Inc

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