Access flow measurement during surveillance and percutaneous transluminal angioplasty intervention.

The introduction of routine access flow measurement methodology has enabled accurate identification of problematic accesses and provided a means for follow-up evaluation. These methods have uncovered, in some cases, that interventions are either immediately unsuccessful or that they fail within 3 months to maintain flow above preintervention levels. The purpose of this article is to analyze the main problems that occur at each step in the loop of flow surveillance-intervention-follow-up and to provide suggestions for improving outcomes. Analysis of published access flow data suggests that the main problems lie in the areas of inadequate analysis of flow surveillance data, lack of objective technology for quantifying intervention effectiveness, and lack of follow-up flow measurements in the hemodialysis (HD) unit after the intervention. The following three recommendations may improve surveillance outcomes: 1). using a reliable access flow technology combined with analysis of all hemodynamic data (including mean arterial pressure) before referring patients for angiography to decrease surveillance false positives; 2). performing intra-access blood flow measurement during angioplasty, which may improve outcomes by giving warning of errors before the patient leaves the intervention suite. Success achieved in restoring flow as measured during the intervention usually predicts good immediate outcomes in the HD unit; 3). measuring access flows during the next week after angioplasty. If the results are unsatisfactory, the patient should be further evaluated to avoid a potential thrombotic event.