Arterio-Venous Fistula Recirculation in Hemodialysis: Causes and Prevalence

Abstract

emodialysis access recirculation is an important cause of inadequate dialysis delivery to individual patients. It is important to diagnose recirculation in order to optimize dialysis delivery. In addition, screening for recirculation may be used as a surveillance technique for the early detection of fistula stenosis, the correction of which may prevent thrombosis. Hemodialysis access recirculation occurs when dialyzed blood returning through the venous needle re-enters the extracorporeal circuit through the arterial needle, rather than returning to the systemic circulation. The re-entry of dialyzed blood into the extracorporeal circuit reduces solute concentration gradients across the dialysis membrane by mixing already dialyzed blood with undialyzed blood. Such mixing reduces the efficiency of dialysis. Significant recirculation can lead to a discrepancy between the amount of hemodialysis prescribed (prescribed Kt/V urea) and the amount of hemodialysis delivered (delivered Kt/V urea). The presence of access recirculation should be suspected when there is an inadequate reduction in the BUC, as shown by the post-dialysis BUC exceeding 40 percent of the pre-dialysis BUC. Therefore high degrees of access recirculation in long term can lead to significant inadequate dialysis. It is well established that inadequate dialysis is an important contributor to lower overall survival among these patients.