Cumulative intravenous fluid volume in the first 24 hours and risk of respiratory deterioration in children hospitalized with community acquired pneumonia

Background: Intravenous (IV) fluids are frequently administered to children hospitalized with community-acquired pneumonia (CAP), yet excessive early IV volume may worsen gas exchange in inflamed lungs. We evaluated whether cumulative IV fluid exposure during the first 24 h was associated with subsequent respiratory deterioration. Methods: We conducted a single-center observational study using electronic health record data and a prespecified 24-hour landmark design. Early IV fluid exposure was quantified as the fluid-to-maintenance ratio (FMR), defined as total IV volume in 0-24 h divided by predicted 24-hour maintenance volume using Holliday-Segar and categorized into quartiles. The primary outcome was respiratory deterioration between 24 and 72 h, defined as escalation to high-flow nasal cannula, noninvasive ventilation, or invasive mechanical ventilation and/or ICU transfer for respiratory support. Associations were assessed using multivariable logistic regression, restricted cubic splines, overlap weighting for Q4 vs. Q1-Q3, and prespecified sensitivity/subgroup analyses. Results: < 0.001). In the complete-case procalcitonin (PCT) subset, the estimate attenuated after additional adjustment for log(PCT) (adjusted OR 1.18, 95% CI 0.98-1.43). Conclusions: Higher IV fluid exposure relative to maintenance during the first 24 h was associated with increased risk of subsequent respiratory deterioration in children hospitalized with CAP. These findings support prospective validation and evaluation of maintenance-aware IV fluid approaches.