Hypernatremia Is Associated with Increased Risk of Mortality in Pediatric Severe Traumatic Brain Injury

Acquired hypernatremia in hospitalized patients is often associated with poorer outcomes. Our aim was to evaluate the relationship between acquired hypernatremia and outcome in children with severe traumatic brain injury (sTBI). We performed a retrospective cohort study of all severely injured trauma patients (Injury Severity Score >= 12) with sTBI (Glasgow Coma Scale [GCS] <= 8 and Maximum Abbreviated Injury Scale [MAIS] >= 4) admitted to a Pediatric Critical Care Unit ([PCCU]; 2000-2009). In a cohort of 165 patients, 76% had normonatremia (135-150 mmol/L), 18% had hypernatremia (151-160 mmol/L), and 6% had severe hypernatremia (> 160 mmol/L). The groups were similar except for lower GCS (p = 0.002) and increased incidence of fixed pupil(s) on admission in both hypernatremia groups (p < 0.001). Mortality rate was four-fold and six-fold greater with hypernatremia and severe hypernatremia, respectively (p < 0.001), and mortality rates were unchanged when patients with fixed pupils or those with central diabetes insipidus were excluded (p < 0.001). Hypernatremic patients had fewer ventilator-free days (p < 0.001). Survivors with hypernatremia had greater PCCU (p = 0.001) and hospital (p = 0.031) lengths of stays and were less frequently discharged home (p = 0.008). Logistic regression analyses of patient characteristics and sTBI interventions demonstrated that hypernatremia was independently associated with the presence of fixed pupil(s) on admission (odds ratio [OR] 5.38; p = 0.003); administration of thiopental (OR 8.64; p = 0.014), and development of central diabetes insipidus (OR 5.66; p = 0.005). Additional logistic regression analyses demonstrated a significant association between hypernatremia and mortality (OR 6.660; p = 0.034). In summary, acquired hypernatremia appears to signal higher risk of mortality in pediatric sTBI and is associated with a higher discharge level of care in sTBI survivors.