Adjunctive metolazone in critically ill children with moderate-to-severe acute kidney injury and furosemide-refractory fluid overload.

BACKGROUND: Data on metolazone in children with fluid overload and moderate-to-severe acute kidney injury (AKI) inadequately responsive to continuous furosemide infusion are limited. We describe its use and factors associated with kidney replacement therapy (KRT). METHODS: This retrospective cohort study in a pediatric intensive care unit included patients with KDIGO stage 2/3 AKI, continuous furosemide infusion, metolazone for inadequate urine output, and no chronic dialysis. Urine output was compared between the 6 h before metolazone and predefined 48-h intervals. Multivariable logistic regression and receiver operating characteristic (ROC) analysis evaluated associations with KRT. RESULTS: Of 196 metolazone-treated children, 62 met inclusion criteria. Median age was 40.5 months (IQR 11-144.5); 61% had stage 3 AKI, 90% were invasively ventilated, and median vasoactive-inotropic score was 10 (IQR 0-26). Median urine output increased from 0.8 mL/kg/h before metolazone to 1.49, 1.37, 2.5, and 2.68 mL/kg/h during 0-6, 6-12, 12-24, and 24-48 h, respectively (all p < 0.01). Children received a median of 3 doses over 48 h. Twenty children (32%) required KRT. Greater 12-24-h urine-output increase was associated with lower KRT odds (odds ratio 0.59, 95% CI 0.36-0.96; p = 0.034). AUC was 0.708 (95% CI 0.568-0.849; p = 0.010), with optimal cutoff ≥ 0.85 mL/kg/h; in 24-h landmark analysis, AUC was 0.683 (95% CI 0.527-0.838; p = 0.021), with the same cutoff. CONCLUSIONS: Metolazone initiation was followed by increased urine output. Response was associated with lower KRT likelihood. These exploratory findings require prospective validation.