Divergence Between Net Fluid and Weight-Based Evaluation in Calculating Cumulative Fluid Balance

Area of Science:

• Pediatric Critical Care Medicine
• Fluid Management
• Intensive Care Unit (ICU) Research

Background:

• Standardizing fluid balance calculations in the ICU is ongoing.
• Limited understanding exists on how different fluid balance calculation methods compare during an ICU stay.
• Accurate fluid balance is crucial for managing critically ill patients.

Purpose of the Study:

• To quantify the agreement between cumulative fluid balance from fluid intake/output (CFBf) and cumulative fluid balance from serial weights (CFBw).
• To analyze these differences in critically ill children during their first week of ICU admission.

Main Methods:

• Retrospective, multicenter, federated observational study.
• Inclusion of 8,895 pediatric patients across 6 ICUs (4 PICU, 2 PCICU).
• Bland-Altman analyses to assess agreement between CFBf and CFBw, stratified by ICU day and patient subgroups.

Main Results:

• CFBf consistently exceeded CFBw across all patient groups (mean difference: 4.7% CFB).
• The divergence between CFBf and CFBw increased significantly over time (2.7% on days 0-3 vs. 8.1% on days 4-7).
• Greater discrepancies were observed in neonates and patients with early anchor weights.

Conclusions:

• Clinicians must recognize the consistent overestimation of fluid balance by CFBf compared to CFBw.
• Prioritizing early and frequent patient weight measurements is essential throughout ICU admission.
• Future research should correlate fluid balance methods with patient outcomes to determine clinical utility.