Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Role of Surveillance for Hemodialysis Access
The role of surveillance for permanent hemodialysis arteriovenous access, both autogenous (arteriovenous fistula [AVF]) and prosthetic (arteriovenous graft [AVG]), remains unresolved. Simplistically, clinical monitoring refers to the “examination and evaluation of vascular access by means of physical examination to detect physical signs that suggest the presence of dysfunction,” and surveillance refers to the “periodic evaluation of the vascular access by using tests that may involve special instrumentation and for which an abnormal test result suggests the presence of dysfunction” as defined by Work. Several of the national practice guidelines, most notably the National Kidney Foundation–Kidney Disease Outcome Quality Initiative (KDOQI), recommend surveillance as a supplement to clinical monitoring. Indeed, one of the two overarching goals of the KDOQI Guidelines is to detect access dysfunction before thrombosis. However, the level 1 evidence from randomized trials does not support routine surveillance and remediation for AVG, and there is a paucity of evidence for AVF. Notably, surveillance does not appear to improve access outcome in terms of functional patency, but it is significantly more expensive. The goal of identifying significant lesions destined to cause access thrombosis and correcting these lesions before any untoward event while avoiding unnecessary procedures is admirable, but it remains elusive.
Justification
Routine surveillance of AVG and AVF seems justified given their natural history and the costs and morbidity associated with failure. Notably, all types of permanent access have a limited life expectancy and ultimately fail or thrombose. The most common mode of failure for AVG is the development of a hemodynamically significant stenosis at the venous outflow (usually the anastomosis) secondary to intimal hyperplasia. Access thrombosis mandates attempts to remove the thrombus and restore the access and/or establish an alternative access, commonly a tunneled dialysis catheter. This care process and untoward series of events often mandates hospital admission and is associated with significant cost and inconvenience to the patient. Theoretically, identifying these significant outflow lesions and preemptive correction with either open or endovascular treatment could prolong access patency and avoid the sequence of adverse events associated with thrombosis.
Surveillance is predicated on the assumptions that the various screening tools can identify a significant stenosis, that these “failing” accesses are destined to fail in the near future, that remedial intervention can prolong patency, and that the outcomes after remediation for the “failing” access are superior to those after a thrombosed access. Unfortunately, not all of these assumptions are necessarily true. The various surveillance techniques (detailed below) are quite good for identifying access stenoses, although the positive predictive value of these lesions in terms of near-term access thrombosis is somewhat limited. Additionally, preemptive angioplasty can stimulate or exacerbate the intimal hyperplastic process and thereby potentially accelerate the failure mode while incurring additional health care costs.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here