Preservation of vascular access.

Preservation of vascular access is critical in the long-term successful management of hemodialysis patients. Dialysis access abnormalities are the most common cause of hospitalization in this patient group, and access problems can increase the morbidity and cost involved in the care of these patients. Native fistulas are preferable to synthetic grafts because of longer survival and a lower complication rate. Venous outflow stenosis is the most common site of obstruction in a failing graft. The pathophysiology of access failure is poorly understood, but it seems to be related to intimal hyperplasia in the native vessel downstream from the anastomosis. The stimulation of local growth factors by needle puncture may also play a role. An assessment of access adequacy includes careful physical examination, laboratory evaluation, and ultimately, angiography. Measurements of recirculation and venous pressure are commonly used to screen for access dysfunction, and their appropriate use will lower the incidence of graft loss in dialysis units. Treatment is usually either angioplasty or surgery, with some centers having success with thrombolytic therapy. New techniques such as atherectomy and stent placement may prove to be beneficial, but this requires further study.