Achievement of fluid removal targets during intermittent renal replacement therapy in the intensive care unit

Background In patients with acute kidney injury (AKI), fluid balance management often relies on the prescription and achievement of fluid removal using intermittent renal replacement therapy (IRRT). This study aimed to describe characteristics associated with the failure to achieve target fluid removal (FATFR). Methods This is a retrospective cohort study including IRRT sessions of conventional duration (<5 hours) performed for AKI in the intensive care unit (ICU) from 2017 to 2022 at a tertiary academic center. FATFR-50% was defined as fluid removal of <50% of the prescribed target. Characteristics of patients and sessions, as well as outcomes at 90 days were collected. The causes of FATFR were manually adjudicated. Results A total of 291 patients and 1280 IRRT sessions in the ICU were included. FATFR-50% occurred in 7.3% of sessions and 19.2% of patients had at least one session with FATFR-50% during the first week of IRRT. Sessions with FATFR-50% were characterized by a higher occurrence of intradialytic hypotension (24.2% vs 60.2%, P < .001) and a higher planned fluid removal (6.19 vs 5.27 m/kg/h, P = .02). Multiple episodes of FATFR-50% were associated with a positive cumulative fluid balance (beta 3876 (CI 2053-5899) P < .001). At 90-day follow-up, FATFR-50% during the first week after IRRT initiation was independently associated with fewer ICU- and hospital-free days, as well as with a higher risk of mortality (odds ratio 2.01 CI 1.04-3.89, P = .04). Conclusions FATFR occurs in about one out of five critically ill patients within the first week of IRRT and is associated with adverse clinical outcomes.