Setting and securing net ultrafiltration during renal replacement therapy in the intensive care unit

Soustraction hydrosodée en épuration extra-rénale

Abstract

Net ultrafiltration (UF_NET) is a critical setting in renal replacement therapy (RRT), which aims at controlling fluid balance and prevent fluid overload. Excessive UF_NET rates may precipitate hemodynamic instability in preload-dependent patients, but additional mechanisms, independent of UF_NET settings, may also contribute to this severe complication, which is associated with increased mortality. Safe fluid removal through UF_NET may require advanced, protocolized hemodynamic monitoring, particularly in patients with acute circulatory failure, and should be combined with optimization of adjunctive RRT settings across intermittent and continuous modalities. UF_NET prescription should be guided by (i) therapeutic goals (neutral or negative fluid balance), (ii) intensity (both in terms of cumulative volume and rate), (iii) safety measures (e.g., continuous cardiac output monitoring), and (iv) frequent reassessment. Strategies of fluid balance control with UF_NET—whether early or delayed—require evaluation in large randomized controlled trials, with patient-centered outcomes, and including careful consideration of the inherent risk of hemodynamic instability associated with excessive fluid removal.