Hyponatremia in children with bronchiolitis admitted to the pediatric intensive care unit is associated with worse outcomes.

OBJECTIVE To characterize the relationship between hyponatremia (serum sodium <135 mEq/L) and clinical outcomes in children ages 1 month to 2 years admitted to the pediatric intensive care unit (PICU) with bronchiolitis. STUDY DESIGN Single-center retrospective cohort study comprising children who were admitted to the PICU between January 2009 and April 2011. Serum sodium concentrations, collected within the first 2 hours after admission to the PICU, were recorded and associations with clinical outcomes were calculated. Quantitative data are presented as mean ± SD or percentage. Student t-test, Fisher exact test, and χ(2) analyses were performed as appropriate. Subjects were excluded if they were previously diagnosed with chronic disease that would affect initial serum sodium concentration. RESULTS Children with bronchiolitis were enrolled (n = 102; age = 10.7 ± 6.7 months). Twenty-three patients (22%) were diagnosed with hyponatremia within 2 hours of admission. Mortality (13% vs 0%; P = .011), ventilator time (8.41 ± 2 days vs 4.11 ± 2 days; P = .001), duration of stay in the PICU (10.63 ± 2.5 days vs 5.82 ± 2.09 days; P = .007), and noninvasive ventilator support (65% vs 24%; P = .007) were significantly different between subjects with hyponatremia vs those without. There were no differences in the number of patients with seizures, bronchodilator use, steroid use, intubation requirement, oxygen use at discharge, or hospital readmission. CONCLUSIONS Pediatric patients diagnosed with bronchiolitis who present with a serum sodium concentration less than 135 mEq/L within 2 hours of admission to the PICU fare worse than their cohorts with normonatremia. A prospective study to evaluate the effects of hyponatremia appears justified.