Systemic effects of a high-flow arteriovenous fistula for hemodialysis.

Purpose: Absolute treatment criteria for reducing the access volume of a high-flow access (HFA, access flow>2 L/min) are absent. Previous studies suggested that a HFA may influence the systemic circulation including blood pressure (BP) and heart rate (HR). The aim of this study was to determine these parameters after access clamping in hemodialysis patients undergoing flow-reducing access surgery.
Methods: Systolic BP (SBP), diastolic BP (DBP) and HR in HFA patients undergoing flow-reducing surgery were measured intraoperatively before and after access clamping. Data were compared to values obtained in patients receiving surgery for severe hand ischemia due to an access (HAIDI, hemodialysis access-induced distal ischemia).
Results: In 8 years, 34 patients underwent surgery for HFA (n=23) or HAIDI (n=11). Preoperative access flows in HFA were larger compared to HAIDI (3,026±147 vs 1,078±139 mL/min, respectively, p<0.001). Temporary clamping (15 sec) caused a 12±2 mm Hg increase in SBP (111±6 to 123±6 mm Hg, p<0.05) and a 6±1 mm Hg rise in DBP (57±4 to 63±5 mm Hg, p<0.05) in HFA patients. In contrast, SBP and DBP increases were not significant in HAIDI patients (+6±3 and +2±2 mm Hg, respectively, p=0.37). HR was modestly reduced in both groups following access clamping (-3±1 beats/min). The relationship between access flow volume and alterations in SBP best fitted a quadratic regression model, suggesting cardiovascular exhaustion with progressively higher access flows>2-2.5 L/min.
Conclusions: HFA may influence systemic hemodynamics in some hemodialysis patients. The findings of this study may contribute to a tailored management of a high-flow fistula in this population.