Acetazolamide therapy for metabolic alkalosis in critically ill pediatric patients

Despite a paucity of supporting literature, acetazolamide is commonly used in critically ill children with metabolic alkalosis (elevated plasma bicarbonate [pHco-3] and pH). The objective of this study was to assess the change in 18 hours after initiation of acetazolamide therapy. Retrospective study. PICU of an urban, tertiary-care children's hospital. Mechanically ventilated children (≤ 17 yr) with metabolic alkalosis (pHco-3 ≥ 35 mmol/L). None. Of 153 consecutively screened patients, 61 patients (29 female patients) were enrolled: 18 cardiac patients (after congenital heart disease repair) and 43 noncardiac patients. The cardiac patients were younger than the noncardiac patients (median [interquartile range] age, 0.6 mo [0.3-2.5 mo] vs 7.4 mo [2.8-39.9 mo]; p < 0.00001) and had higher preacetazolamide baseline diuretic scores and urine output. The pHco-3 levels 18 hours after initiation of acetazolamide were reduced in the cohort as a whole (40.2 ± 4.8 to 36.2 ± 5.6 mmol/L; p < 0.001) and in the noncardiac patients, but they were unchanged in the cardiac patients. The PCO2 remained unchanged after acetazolamide in both subgroups. Because young age and presence of cardiac disease were potential confounders, the 20 noncardiac patients who are 6 months old or younger were compared with the cardiac subgroup and demonstrated reduced pHco-3 after acetazolamide and lower preacetazolamide baseline diuretic score and urine output. Acetazolamide reduces pHco-3 concentration in critically ill, mechanically ventilated children overall, but it did not do so in cardiac patients in our cohort, even in comparison with noncardiac patients of a similar age. These findings do not support the current use of acetazolamide for metabolic alkalosis in critically ill children with congenital heart disease. Further study is required to determine why these cardiac patients respond differently to acetazolamide than noncardiac patients and whether this response impacts important clinical outcomes, for example, weaning mechanical ventilation.