Fluid overload and fluid removal in pediatric patients on extracorporeal membrane oxygenation requiring continuous renal replacement therapy: a multicenter retrospective cohort study

Objective: The aim of this study was to characterize continuous renal replacement therapy (CRRT) utilization on extracorporeal membrane oxygenation (ECMO) and to determine the association of both fluid overload (FO) at CRRT initiation and fluid removal during CRRT with mortality in a large multicenter cohort. Methods: Retrospective chart review of all children < 18 years of age concurrently treated with ECMO and CRRT from January 1, 2007, to December 31, 2011, at six tertiary care children’s hospital. Children treated with hemodialysis or peritoneal dialysis were excluded from the FO analysis. Measurements and main results: A total of 756 of the 1009 children supported with ECMO during the study period had complete FO data. Of these, 357 (47.2%) received either CRRT or were treated with an in-line filter and thus entered into the final analysis. Survival to ECMO decannulation was 66.4% and survival to hospital discharge was 44.3%. CRRT initiation occurred at median of 1 day (IQR 0, 2) after ECMO initiation. Median FO at CRRT initiation was 20.1% (IQR 5, 40) and was significantly lower in ECMO survivors vs. non-survivors (15.3% vs. 30.5% p = 0.005) and in hospital survivors vs. non-survivors (13.5% vs. 25.9%, p = 0.004). Median FO at CRRT discontinuation was significantly lower in ECMO survivors (23% vs. 37.6% p = 0.002) and hospital survivors vs. non-survivors (22.6% vs. 36.1%, p = 0.002). In ECMO survivors, after adjusting for pH at CRRT initiation, non-renal complications, ECMO mode, support type, center, patient age and AKI, FO at CRRT initiation (p = 0.01), and FO at CRRT discontinuation (p = 0.0002) were independently associated with duration of ECMO. In a similar multivariable analysis, FO at CRRT initiation (adjusted adds ratio [aOR] 1.09, 95% CI 1.00–1.18, p = 0.045) and at CRRT discontinuation (aOR 1.11, 95% CI 1.03–1.19, p = 0.01) were independently associated with hospital mortality. Conclusions: In a multicenter pediatric ECMO cohort, this study demonstrates that severe FO was very common at CRRT initiation. We found an independent association between the degree of FO at CRRT initiation with adverse outcomes including mortality and increased duration of ECMO support. The results suggest that intervening prior to the development of significant FO may be a clinical therapeutic target and warrants further evaluation.