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

Abstract

Objective Dysnatremia is common in critically ill children due to disruption of hormonal homeostasis. Children with brain injury are at risk for SIADH, cerebral salt wasting and sodium losses due to externalized ventricular drain (EVD) placement. We hypothesized that among pediatric intensive care unit (PICU) patients managed with an EVD, 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 EVD from January 2005 to December 2009. Patients were identified by searching the physician order entry database for EVD orders. Hyponatremia was defined as the minimum sodium during patients’ EVD time and was categorized as mild (131-134 meq/L) or moderate-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 EVD was in use (up to 14 days). Seizure was defined as a clinically evident convulsion during EVD presence. A priori confounders were age, history of epilepsy, and EVD 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%) moderate-severe hyponatremia. Twenty eight (7%) patients had a seizure while hospitalized. Eighteen patients died (5%) prior to discharge. Survivors had a median daily sodium fluctuation of 1 [0, 5] vs non-survivors 9 [6, 11], (p< 0.001) and a median sodium fluctuation of 5 meq/L [interquartile range 2, 8] vs non-survivors 15 meq/L [9, 24] (p<0.001) during EVD 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 (OR 1.38, 95% CI (1.06, 1.8)) and greater fluctuations in sodium during EVD management were associated with increased odds of in-hospital mortality (OR 1.59, 95% CI (1.2, 2.11)). Conclusion Hyponatremia was common in PICU patients treated with EVDs but not associated with seizures or in-hospital mortality. Greater sodium fluctuations during EVD management were independently associated with increased odds of in-hospital mortality.

The association between sodium fluctuations and mortality in surgical patients requiring intensive care

“…The association of sodium fluctuations and mortality has been shown in a large cohort of adult surgical ICU patients [9] and in pediatric ICU patients who require externalized ventriculostomy drains [13]. Our study validates the findings of an independent association between sodium fluctuations and mortality, and also the association between degree of sodium fluctuation and an increased odds of in-hospital mortality.…”

“…A recent study by Sakr and colleagues [9] found an independent association between sodium fluctuations and mortality, even in patients who remained within the reference range throughout their ICU stay. The association of sodium fluctuations and mortality has been validated in only one other study, in a subgroup of a pediatric population requiring externalized ventricular drains [13]. …”

The authors reply

“…As rightly pointed out by Fante et al, we did not observe a statistically significant association between hyponatremia and seizures or hospital mortality (2). This is counter to what has been previously published by others (3–5).…”

Serum sodium variability and acute kidney injury: a retrospective observational cohort study on a hospitalized population

“…Both hyponatremia and hypernatremia have been widely associated with increased morbidity and mortality. Furthermore, as suggested by recently published studies, even small fluctuations in serum Na levels have been associated with a significant increase of in-hospital mortality [5][6][7][8].…”