Fluid accumulation in critically ill children: a systematic review and meta-analysis.

Background: Fluids are often administered for various purposes, such as resuscitation, replacement, maintenance, nutrition, or drug infusion. However, its use is not without risks. Critically ill patients are highly susceptible to fluid accumulation (FA), which is associated with poor outcomes, including organ dysfunction, prolonged mechanical ventilation, extended hospital stays, and increased mortality. This study aimed to assess the association between FA and poor outcomes in critically ill children. Methods: In this systematic review and meta-analysis, we searched PubMed, Embase, ClinicalTrials.gov, and Cochrane Library databases from inception to May 2024. Relevant publications were searched using the following terms: child, children, infant, infants, pediatric, pediatrics, critically ill children, critical illness, critical care, intensive care, pediatric intensive care, pediatric intensive care unit, fluid balance, fluid overload, fluid accumulation, fluid therapy, edema, respiratory failure, respiratory insufficiency, pulmonary edema, mechanical ventilation, hemodynamic instability, shock, sepsis, acute renal failure, acute kidney failure, acute kidney injury, renal replacement therapy, dialysis, mortality. Paediatric studies were considered eligible if they assessed the effect of FA on the outcomes of interest. The main outcome was all-cause mortality. Pooled analyses were performed by using random-effects models. This review was registered on PROSPERO (CRD42023432879). Findings: A total of 120 studies (44,682 children) were included. Thirty-five FA definitions were identified. In general, FA was significantly associated with increased mortality (odds ratio [OR] 4.36; 95% confidence interval [CI] 3.53-5.38), acute kidney injury (OR 1.98; 95% CI 1.60-2.44), prolonged mechanical ventilation (weighted mean difference [WMD] 38.1 h, 95% CI 19.35-56.84), and longer stay in the intensive care unit (WMD 2.29 days; 95% CI 1.19-3.38). The percentage of FA was lower in survivors when compared to non-survivors (WMD -4.95 [95% CI, -6.03 to -3.87]). When considering only studies that controlled for potential confounding variables, the pooled analysis revealed 6% increased odds of mortality associated with each 1% increase in the percentage of FA (adjusted OR = 1.06 [95% CI, 1.04-1.09). Interpretation: FA is significantly associated with poorer outcomes in critically ill children. Thus, clinicians should closely monitor fluid balance, especially when new-onset or worsening organ dysfunction occurs in oedematous patients, indicating potential FA syndrome. Future research should explore interventions like restrictive fluid therapy or de-resuscitation methods. Meanwhile, preventive measures should be prioritized to mitigate FA until further evidence is available. Funding: None.