Influence of definition and location of hypotension on outcome following severe pediatric traumatic brain injury

Objective: To examine the influence of definition and location (field, emergency department, or pediatric intensive care unit) of hypotension on outcome following severe pediatric traumatic brain injury. Design: Retrospective cohort study. Setting: Harborview Medical Center (level I pediatric trauma center), Seattle, WA, over a 5-yr period between 1998 and 2003. Patients: Ninety-three children <14 yrs of age with traumatic brain injury following injury, head Abbreviated Injury Score ≥3, and pediatric intensive care unit admission Glasgow Coma Scale score <9 formed the analytic sample. Data sources included the Harborview Trauma Registry and hospital records. Interventions: None. Measurements and Main Results: The relationship between hypotension and outcome was examined comparing two definitions of hypotension: a) systolic blood pressure <5th percentile for age; and b) systolic blood pressure <90 mm Hg. Hospital discharge Glasgow Outcome Score <4 or disposition of either death or discharge to a skilled nursing facility was considered a poor outcome. Pediatric intensive care unit and hospital length of stay were also examined. Systolic blood pressure <5th percentile for age was more highly associated with poor hospital discharge Glasgow Outcome Score (p = .001), poor disposition (p = .02), pediatric intensive care unit length of stay (rate ratio 9.5; 95% confidence interval 6.7-12.3), and hospital length of stay (rate ratio 18.8; 95% confidence interval 14.0-23.5) than systolic blood pressure <90 mm Hg. Hypotension occurring in either the field or emergency department, but not in the pediatric intensive care unit, was associated with poor Glasgow Outcome Score (p = .008), poor disposition (p = .03), and hospital length of stay (rate ratio 18.7; 95% confidence interval 13.1-24.2). Conclusions: Early hypotension, defined as systolic blood pressure <5th percentile for age in the field and/or emergency department, was a better predictor of poor outcome than delayed hypotension or the use of systolic blood pressure <90 mm Hg.