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Appropriate Vascular Access for Patients with Limited Life Expectancy
A growing number of elderly patients and patients with severe, life-limiting pathologies are reaching advanced kidney disease. If the nephrologist, the patient and family members elect to provide long-term renal replacement therapy, one of the decisions that will have the highest impact on morbidity and quality of life of the patient is the choice of vascular access for dialysis.
How to evaluate for the best access
Choosing the appropriate vascular access comes after identifying long-term goals and the expected survival of the patient once dialysis is initiated. As you evaluate access options for elderly or debilitated patients with advanced kidney disease, consider the following questions.
- When will dialysis be necessary?
- Will the patient die before or shortly after initiating dialysis?
- Will he or she tolerate the hemodynamic load of AVF construction both locally (steal syndrome) or from a general cardiovascular standpoint?
Although an arteriovenous fistula (AVF) is generally considered the best access for most dialysis patients, this is not always the case for patients with limited life expectancy. One objection to constructing an AVF in elderly patients is the fact that death competes with reaching the need to dialyze. In one study, up to 30 percent of patients with a constructed AVF died before needing dialysis. Furthermore, many of the elderly patients who initiate dialysis after AVF placement still need to start renal replacement through a catheter as the AVF often does not develop enough to support hemodialysis. Conversely, an arteriovenous graft (AVG) is more likely to develop in a timely fashion, potentially giving more elderly patients a patent, useful access. An AVG can be placed shortly before the patient needs dialysis—when the actual need to dialyze is more predictable.
Preparing for an access placement
Many nephrologists and vascular surgeons start planning an access placement when the creatinine clearance is between 15 and 20 mL/min/1.73m2. They might start with a distal radiocephalic fistula, with the knowledge that it may not mature. There are arguments that, in the elderly, a proximal brachiocephalic AVF is preferable as a first vascular access, due to the high failure rate of an AVF placed distally.
The skill and experience of the surgeon who places AVFs or AVGs is extremely important. This is particularly relevant in placing the complex AVF with transposed basilic veins. Doppler mapping of the upper limbs (or, sometimes, lower limb) arterial and venous system, before vascular access placement, is becoming the standard of care to minimize the risks of failure. A lifelong vascular access plan is of paramount importance in all age groups.
The availability of expert interventional radiology to diagnose and treat AVF and AVG dysfunction and thrombosis can be valuable. This may be particularly relevant in the elderly, with excellent primary and secondary patency in vascular accesses of octogenarians and nonagenarians subjected to endovascular interventions.
Decisions on access choice: A tough task
It is important to remember that the basis of evidenced-based medicine is the randomized controlled clinical trial. Due to ethical reasons, nephrologists would not randomly allocate patients to an AVF, AVG or a catheter and study the long-term clinical results of the three cohorts. This three-way comparison would be the ideal way to prevent bias and sort out the true impact of the vascular access on patient survival. In retrospective analysis, patients with a catheter die more than patients with an AVF and AVG, but we are not comparing the access options fairly. The nephrologist may decide not to request AVF or AVG placement because of the patient’s limited life expectancy. In fact, researchers point to the fact that the difference in mortality between catheter versus AVF or AVG, is mostly due to comorbid conditions.
The previous point does not mean that nephrologists should not aim to reduce the number of catheters, including catheters for elderly patients with a fair life expectancy. The advantages of non-catheter access is quite obvious, namely preventing severe blood borne infections, including devastating damage in cases of endocarditis or spondylodiscitis. Central stenosis/thrombosis is an additional problem. Furthermore, irrespective of age, AVF is the ideal vascular access, due to lower incidence of thrombosis and infection, but unlike the presence of catheters, having an AVG rather than an AVF does not seem to impact survival in the elderly over 80 years.
Common sense needs to be used, as in all areas of medicine. Therefore, if a short survival is expected, the tunneled catheter is the most reasonable choice for a vascular access. Many authors suggest that if the patient is expected to live for more than 180 days, ideally an AVF should be placed, although an AVG may be a quite reasonable alternative.
Note: Some of this content has been republished, with permission, from Nephrology News & Issues.