PURPOSE: Bronchiolitis is one of the most common causes of hospitalization and critical illness in children. Critically ill children often develop electrolyte imbalances such as hyponatremia. The mechanisms for this process are incompletely understood; possibilities include fluid overload, capillary leak, or syndrome of inappropriate antidiuretic hormone secretion. We hypothesized that hyponatremia was associated with a more complicated clinical course in critically ill children with bronchiolitis.
METHODS: A retrospective review was conducted of all children admitted to the ICU with bronchiolitis between January 1, 2005 and December 31, 2006 (n=59). Two groups were analyzed: those that became hyponatremic (serum sodium < 136 mmol/L) and those that remained normonatremic.
RESULTS: Forty-three of fifty-nine children (73%) developed hyponatremia while in the ICU. There were no significant differences in age, gender, or race between those who developed hyponatremia and those that remained normonatremic. Hyponatremic children were more likely to be intubated than normonatremic children (OR 16.7; 95% CI 4.1-68.5); however, hyponatremia rarely developed before intubation (2%). Thirty-eight of the forty-three children (88%) who were intubated for bronchiolitis developed hyponatremia. These intubated children had a lower mean serum sodium concentration (132.8 vs. 137.3, p< 0.0001) than non-intubated children. Hyponatremic children also had a longer ICU length of stay than those who remained normonatremic (9.5 ± 5.2 days vs. 3.8 ± 3.6 days, p<0.0002).
CONCLUSION: Hyponatremia was a common comorbidity in children admitted to the ICU with bronchiolitis. Intubated children with bronchiolitis developed hyponatremia more often than non-intubated counterparts, and their mean serum sodium concentrations were lower. Hyponatremia may have contributed to the severity of illness or may have been an effect of the severity of illness. Regardless, this study supports our hypothesis that hyponatremia is a marker of illness severity in bronchiolitis.
CLINICAL IMPLICATIONS: Hyponatremia was associated with a more complex clinical course in critically ill children with bronchiolitis. Prospective trials are necessary to determine the etiologies and clinical significance of hyponatremia in this population, and whether control of hyponatremia will improve outcomes.
DISCLOSURE: Michael Seifert, No Financial Disclosure Information; No Product/Research Disclosure Information