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Analysis of New Methods for Access Monitoring

As hemodialysis technology has improved, the vascular access looms larger as an obstacle to both delivering adequate dialysis and to improving the patient’s quality of life. Maintenance of the access device is now a major expense that consumes a significant fraction of the budget for health care, arousing the attention of more than just the patients and healthcare workers (1). Efforts to understand the pathogenesis of AV graft failure have uncovered a consistent pattern of fibromuscular intimal hyperplasia, most often at or near the venous anastomosis. Progressive stenosis caused by this lesion reduces blood flow, causes dialyzed blood to recirculate through the access device during treatment, and ultimately leads to thrombosis. Salvaging a thrombosed access is usually an emergent procedure that, if not immediately successful, causes delays in dialysis treatment and may require placement of temporary dialysis catheters. The delays and invasive placement of catheters further endanger the patient’s life, add to the cost, and create inconvenience for the patient and those who must scramble to correct the problem. Ten years ago, Schwab et al. showed that pressure on the venous side of the dialyzer circuit, when carefully and systematically measured, can predict access failure and target patients for angiography to detect and correct venous stenosis (2). These and other studies showed that thrombolysis and thrombectomy when combined with percutaneous angioplasty or surgical revision significantly prolonged the life of the access (2–5). Over the past four years, several investigators have shown that blood flow through the access device can more accurately predict access thrombosis and allow timely intervention to restore flow and prevent clotting (6–9). The following discussion is a brief review of the techniques currently available for monitoring peripheral A-V access devices and the evidence for patient benefits.