Fluid balance after continuous renal replacement therapy initiation and outcome in paediatric multiple organ failure

Patients with multiple organ failure (MOF) often receive large amounts of resuscitation fluid, making them at high risk of fluid overload (FO). Our main objective was to investigate if the ability to achieve a negative fluid balance during the first 3 continuous renal replacement therapy (CRRT) days was associated with mortality in children with MOF.

Retrospective cohort study in a tertiary multidisciplinary academic paediatric hospital. The study included 63 patients (age 0-18 years) with 3 or more failing organs receiving CRRT due to acute kidney injury and/or fluid overload.

The median age was 4 months, and PICU mortality was 29%. Survivors had significantly lower degree of FO at CRRT initiation, (median 15% (Interquartile range 9-22)) than non-survivors (24% (17%-37%), P = 0.002). On PICU admission, PIM-3 score was significantly higher in non-survivors (P = 0.01), but at CRRT initiation there was no difference in PELOD-2 score (P = 0.98). Mortality in patients achieving a cumulative net negative fluid balance during the first 3 days after CRRT initiation was 12%, compared to 86% in those not achieving this (P < 0.0001). In multivariate analysis, the inability to achieve a net negative fluid balance during 3 days after CRRT initiation (P < 0.0001) and FO >20% at CRRT initiation (P = 0.0019) remained associated with mortality.

Our results suggest that early fluid removal is associated with improved patient outcome in critically ill children receiving CRRT, and that prompt measures should be taken to prevent fluid overload in critical illness. These results need to be verified in further, prospective studies.