Introduction: Fluid overload (FO), a state of pathologic positive cumulative fluid balance (CFB), is common in Pediatric Intensive Care Units (PICU) and associated with morbidity and mortality. Because different PICUs may have unique needs, barriers, and limitations to accurately report fluid balance (FB) and reduce FO, understanding the drivers of positive FB is needed. We hypothesize CFB >5% and >10% is common within initial days of PICU admission, but that reasons for high %CFB will vary across sites, as will barriers to accurate FB recording and opportunities to improve FB recording and management. Methods: Concurrent mixed methods study utilizing a retrospective observational cohort design and prospective interview and survey design performed at four tertiary pediatric ICUs. FB data was extracted from the electronic health record. A federated data collection framework allowed for rapid data aggregation. The primary outcome was %CFB on PICU days 1 and 2, defined as total intake minus total output divided by PICU admission weight. Chi-square test and Wilcoxon rank sum tests compared results across and within sites. Results: Amongst 3,071 PICU encounters, day 2 CFB >5% varied from 39% to 54% (p=0.03) and day 2 CFB >10% varied from 16% to 25% (p=0.04) across sites. Urine occurrence recordings and patients receiving >100% Holliday-Segar fluids on Day 1 differed across sites (p<0.001). Sites discussed overall FB and specific FB goals on rounds with differing frequency (42-73% and 19-39%, respectively), but they reported similar barriers to accurate FB reporting and achievable opportunities to improve FB measurements. Conclusion: Day 2 CFB >5% and >10% was common among PICU encounters but proportion of patients varied significantly across PICUs. Individual ICUs have different drivers of FO that must be targeted to improve FB management.

The authors have declared no competing interest.

This study did not receive any funding

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