The Challenges of Hemodialysis Access
Mark P. Androes
David L. Cull
Christopher G. Carsten III
The morbidity and cost associated with end-stage renal disease in general, and vascular access in particular, have emerged as major areas of concern facing our society in the 21st century. Between 1991 and 2001, the number of patients in the Medicare End Stage Renal Disease Program doubled from 201,000 to more than 400,000. The cost associated with the program now approximates $23 billion annually and consumes 6.4% of the entire Medicare budget. It is estimated that 17% of the end-stage renal disease budget is spent on the establishment and maintenance of dialysis access. These statistics have stimulated a reassessment of previous assumptions and current practice patterns related to vascular access.
In 1966, Brescia and colleagues described the surgical technique for creating an arteriovenous fistula, the autogenous radial-cephalic access, which could be repetitively cannulated and thereby used to maintain patients on chronic hemodialysis. Patient selection for chronic hemodialysis during this period was stringent. Most patients were young men with minimal comorbidities, and diabetic nephropathy was generally considered a contraindication for dialysis support. The favorable arterial and venous anatomy within this population permitted the creation of an autogenous radial-cephalic access in the majority of patients. Outcome studies for the autogenous radial-cephalic access during this period reported excellent long-term patency and nonmaturation rates of only 8% to 12%. By virtue of these early results, the autogenous radial-cephalic access quickly earned the reputation as the “gold standard” of vascular access, a label that persists today.
Despite the early reports documenting the outcome of the radial-cephalic autogenous access, there has been a shift from autogenous to prosthetic access use in the United States. The institution of government funding for treating patients with end-stage renal disease in 1972 resulted in the liberalization of the patient treatment criteria and a change in the demographics of the hemodialysis population (Table 82-1). The net effect was an increase in the prevalence of the patient factors that adversely affect autogenous access maturation and patency, including advanced age, diabetes mellitus, female gender, and peripheral vascular disease. Furthermore, there was a change in the approach to hemodialysis during the 1980s, with an emphasis on dialysis adequacy, necessitating that the obligatory access flow rates be increased from 250 cc per minute to 400 cc per minute. Smaller autogenous accesses that previously would have been adequate for dialysis often were unable to sustain these increased flow rates. Consequently, the early failure and nonmaturation rates for the autogenous radial-cephalic access have increased to between 20% and 50% in more recent series. However, with the increased use of prosthetic accesses, it has become apparent that they are prone to a disturbing incidence of complications, such as thrombosis and infection.
The staggering morbidity and financial burden associated with hemodialysis vascular access have prompted efforts to use the principles of evidence-based medicine to determine the outcome of access procedures and to standardize its management. The most influential of these efforts has been the National Kidney Foundation’s Dialysis Outcome Quality Initiative Clinical Practice Guidelines for Vascular Access (DOQI Guidelines). Based on the conclusions and recommendations of this document, there has been an increased emphasis on the placement of the autogenous radial—cephalic access and secondary autogenous procedures. A significant amount of additional work is necessary before a standardized approach to vascular access can be developed for the heterogenous hemodialysis population. The studies reporting the outcome of vascular access procedures are almost exclusively retrospective, often have contradictory conclusions, and rarely define patient selection criteria. Therefore, the vascular access surgeon has little solid evidence on which to base his/her clinical decisions as to the most appropriate type and site for access placement. Furthermore, the surgeon must decide on the appropriate pre-operative evaluation and choose among a number of prosthetic graft materials and manufacturers.
The major vascular access questions that need to be addressed include the following:
What factors (or combination of factors) predict failure/success of the autogenous access maturation, and when should a prosthetic access be used?
Is it possible to significantly increase the use of autogenous accesses in the current hemodialysis population, which is becoming increasingly older and sicker?
What is the optimal prosthetic graft material and configuration?
What is the most durable and cost-effective approach to treating access thrombosis?
What is the best method of access surveillance, and is access surveillance cost-effective for the general hemodialysis population?
This chapter will consider the recommendations of the DOQI Guidelines, the evidence-based outcome data related to vascular access, and some of the major issues that need to be addressed to minimize access morbidity and cost in an increasingly complicated hemodialysis population.
Table 82-1 The Demographics and Survival of the End-Stage Renal Disease Population Between 1980 and 2001* | |||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Dialysis Outcome Quality Initiative Clinical Practice Guidelines for Vascular Access
In the early1990s, several studies suggested improved outcome with the use of algorithms for treating various disease processes. This standardization, driven in part by managed care organizations, outcome analyses, and cost-cutting efforts, prompted further analysis of the care provided to patients with end-stage renal disease. In 1994, the National Kidney Foundation began a massive program designed to improve the outcome in patients with end-stage renal disease. The process culminated in 1997 with the publication of the practice recommendations known as the DOQI Guidelines. The objectives of the consensus statement were to improve patient survival, increase the efficiency of care, reduce morbidity, and improve quality of life for dialysis patients. An update of the DOQI Guidelines was published in 2000. The DOQI Vascular Access Work Group (DOQI Work Group) that authored the guidelines was composed of a multidisciplinary team that formally reviewed nearly 3,500 vascular access-related articles. The team evaluated the credibility of these publications and used the best available evidence in the literature to develop the clinical practice guidelines. Where evidence was not available, the guidelines were based on the opinion of the Work Group. For each guideline, there was a clear indication of whether the guideline was based on evidence, opinion, or both.
Recommendations of the DOQI Guidelines
Patient Evaluation Prior to Access Placement
The DOQI Guidelines recommend a venogram prior to access placement in patients with ipsilateral edema, evidence of collateral vein development, and differential extremity size, and in those patients with a history of ipsilateral subclavian vein catheters or pacemakers. A venogram is also suggested in patients with multiple previous ipsilateral access procedures. Interrogation of the central veins with either a duplex ultrasound scan or a magnetic resonance venogram is suggested if contrast studies are contraindicated. Arteriography is indicated when arterial pulses in the ipsilateral extremity are diminished.
The determination of the site, timing, and type of access are key components of the DOQI Guidelines. They strongly favor autogenous over prosthetic accesses. Indeed, the DOQI Guidelines recommend that 50% of the incident accesses be autogenous with a 40% overall autogenous prevalence rate. Cuffed tunneled central venous catheters are associated with significant morbidity and, therefore, are discouraged as permanent vascular access.
The DOQI Guidelines favor the autogenous accesses due to their better patency and lower complication rates. The autogenous radial-cephalic is the first choice of access, usually in the nondominant hand, because it is simple to create, associated with a low incidence of complications including hand ischemia, and preserves proximal vessels for future access. The autogenous brachial-cephalic access is the second choice. It has a higher blood flow rate than the radial-cephalic access but is slightly more difficult to create surgically and may result in more hand ischemia and arm swelling. According to the DOQI Guidelines, the autogenous brachial-basilic transposition is equivalent in preference to that of a prosthetic access. Although several studies have shown better patency rates and reduced infection rates with the brachial-basilic transposition compared to prosthetic accesses, the procedure is more difficult to perform and may have a higher incidence of arm swelling, pain, and hand ischemia. Arm exercise may improve maturation and flow rates of new autogenous accesses. Failure of maturation should result in evaluation and potential intervention to enhance development, and every access failure should be followed by a re-evaluation for a new autogenous access rather than placement of a prosthetic one.
Prosthetic accesses are preferred if an autogenous access cannot be established. The DOQI Guidelines state that prosthetic accesses constructed with polytetrafluoroethylene (PTFE) are preferred to those constructed with other synthetic graft materials. The location and configuration depend on the patient’s anatomy, but the access should provide a large surface area for cannulation. The benefits of prosthetic accesses include a short lag time to maturation, ease of surgical implantation/repair, and multiple insertion sites/configurations. The major disadvantages cited are their reduced patency and increased infectious rates relative to the autogenous accesses.
Cuffed, tunneled catheters are the preferred option for temporary access, and the right internal jugular vein is the preferred access site. Ultrasound-guided catheter insertion is recommended to reduce insertionrelated complications and is supported by several studies. In the opinion of the DOQI Work Group, fluoroscopy should be used to assure proper catheter tip positioning. The use of noncuffed catheters should be limited to acute, short-term hemodialysis needs. Use of cuffed or noncuffed catheters in
the subclavian location should be discouraged in patients requiring permanent access due to the associated high incidence of central venous stenosis.
the subclavian location should be discouraged in patients requiring permanent access due to the associated high incidence of central venous stenosis.
Monitoring, Surveillance, and Diagnostic Testing
In addition to increasing the placement of autogenous accesses, one of the primary goals of the DOQI Guidelines is to reduce access thrombosis by the use of monitoring and surveillance methods to detect and correct access stenoses prior to failure. The term monitoring refers to the evaluation of the access by means of physical examination to detect potential abnormalities, such as changes in the strength or character of the thrill. Surveillance refers to periodic evaluation of the access by means of some type of testing modality to identify a similar underlying problem or defect. The DOQI Guidelines recommend physical examination (monitoring) of the access weekly. The examination should include inspection and palpation for the respective pulse and/or thrill at the arterial, mid, and venous sections of the prosthetic accesses or at corresponding locations for the autogenous accesses. The clinical assessment and dialysis adequacy should be collected and tracked within the dialysis center.
The DOQI Guidelines cite evidence that prospective surveillance of prosthetic accesses for hemodynamically significant stenosis improves patency when the significant lesions are corrected. A number of surveillance techniques are available. The DOQI Work Group has determined that the preferred techniques in order of decreasing preference are access flow rates, static venous dialysis pressures, and dynamic venous pressures. Other studies, such as measurement of access recirculation and decreases in the adequacy of dialysis, can be useful. Persistent abnormalities of these surveillance studies should prompt a fistulagram to evaluate the access, and the DOQI Guidelines provide protocols for these studies.
Optimal Approaches for Treating Complications
A stenosis that occurs in an autogenous or prosthetic access should be treated with percutaneous angioplasty or surgical revision if the stenosis exceeds 50% and it is associated with clinical or physiologic abnormalities, such as decreasing access flow rates, elevated venous dialysis pressures, or abnormal physical findings. The postprocedure stenosis should be less than 30%, and the clinical and/or physiologic abnormalities should be corrected after the intervention. The DOQI Work Group recommends that the procedure used to treat the stenosis (surgical revision versus angioplasty) be determined by the expertise at the specific center.
Thrombosis of a prosthetic access should be corrected with either surgical thrombectomy or with pharmacomechanical/mechanical thrombolysis. The DOQI Guidelines do not favor one technique but state that the choice should be based on the expertise of the specific center. Prosthetic access thrombosis should be treated promptly to minimize the need for temporary access. The access should be evaluated by fistulagram after thrombectomy or thrombolysis to detect residual stenoses, and all significant lesions should be corrected by percutaneous angioplasty or open, surgical revision.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
