Purpose of review: This review critically summarizes the evidence linking ultrafiltration rates to adverse outcomes among hemodialysis patients and provides research recommendations to address knowledge gaps.
Recent findings: Growing evidence suggests that fluid-related factors play important roles in hemodialysis patient outcomes. Ultrafiltration rate - the rate of fluid removal during hemodialysis - is one such factor. Existing observational data suggest a robust association between greater ultrafiltration rates and adverse cardiovascular outcomes, and such findings are supported by plausible physiologic rationale. Potential mechanistic pathways include ultrafiltration-related ischemia to the heart, brain, and gut, and volume overload-precipitated cardiac stress from reactive measures to ultrafiltration-induced hemodynamic instability. Inter-relationships among ultrafiltration rates and other fluid measures, such as interdialytic weight gain and chronic volume expansion, render the specific role of ultrafiltration rates in adverse outcomes difficult to study. Randomized trials must be conducted to confirm epidemiologic findings and examine the effect of ultrafiltration rate reduction on clinical and patient-centered outcomes.
Summary: Compelling observational data demonstrate an association between more rapid ultrafiltration rates and adverse clinical outcomes. Before translating these findings into clinical practice, randomized trials are needed to verify observational data results and to identify effective strategies to mitigate ultrafiltration-related risk.