Greater Fluctuations in Serum Sodium Levels Are Associated With Increased Mortality in Children With Externalized Ventriculostomy Drains in a PICU*

Objectives: Dysnatremia is common in critically ill children due to disruption of hormonal homeostasis. Children with brain injury are at risk for syndrome of inappropriate antidiuretic hormone, cerebral salt wasting, and sodium losses due to externalized ventricular drain placement. We hypothesized that among PICU patients managed with an externalized ventricular drain, hyponatremia is common, hyponatremia is associated with seizures and in-hospital mortality, and greater sodium fluctuations are associated with in-hospital mortality. Design: Retrospective observational study. Setting: Tertiary care PICU. Patients: All pediatric patients treated in the PICU with an externalized ventricular drain from January 2005 to December 2009. Patients were identified by searching the physician order entry database for externalized ventricular drain orders. Hyponatremia was defined as the minimum sodium during patients’ externalized ventricular drain time and was categorized as mild (131–134 mEq/L) or moderate to severe (⩽ 130 mEq/L). Magnitude of sodium fluctuation was defined as the difference between a patient’s highest and lowest sodium during the time in which an externalized ventricular drain was in use (up to 14 d). Seizure was defined as a clinically evident convulsion during externalized ventricular drain presence. A priori confounders were age, history of epilepsy, and externalized ventricular drain indication. Multivariable regression was performed to test the association between sodium derangements and outcomes. Interventions: None. Measurements and Main Results: Three hundred eighty patients were eligible. One hundred nine (29%) had mild hyponatremia, and 30 (8%) had moderate to severe hyponatremia. Twenty-eight patients (7%) had a seizure while hospitalized. Eighteen patients died (5%) prior to discharge. Survivors had a median daily sodium fluctuation of 1 mEq/L [0–5] vs non-survivors 9 mEq/L [6–11] (p < 0.001) and a median sodium fluctuation of 5 mEq/L [2–8] vs non-survivors 15 mEq/L [9–24] (p < 0.001) during externalized ventricular drain management. After controlling for a priori covariates and potential confounders, hyponatremia was not associated with an increased odds of seizures or in-hospital mortality. However, greater fluctuations in daily sodium (odds ratio, 1.38; 95% CI, 1.06–1.8) and greater fluctuations in sodium during externalized ventricular drain management were associated with increased odds of in-hospital mortality (odds ratio, 1.59; 95% CI, 1.2–2.11). Conclusions: Hyponatremia was common in PICU patients treated with externalized ventricular drains but not associated with seizures or in-hospital mortality. Greater sodium fluctuations during externalized ventricular drain management were independently associated with increased odds of in-hospital mortality.