Abstract 4: The Effect of Prehospital Hypoxia and Hypotension on Outcome in Major Traumatic Brain Injury: A Deadly Combination

Abstract

BACKGROUND: Hypoxia (HOx) or hypotension (HT) occurring during the EMS management of major traumatic brain injury-TBI reduces survival. However, little is known about the impact of both HOx and HT, occurring together, on outcome. Only a handful of reports have studied the combination of prehospital HOx/HT in TBI and the largest of these only had 14 cases with both. Objectives: To evaluate the associations between mortality and prehospital HOx and HT, both separately and in combination. METHODS: All moderate/severe TBI cases (CDC Barell Matrix Type-1) in the Excellence in Prehospital Injury Care (EPIC) TBI Study (a statewide, before/after controlled study of the impact of implementing the EMS TBI Treatment Guidelines-NIH/NINDS: 1R01NS071049) from 1/1/08-6/30/12 were evaluated [exclusions: age<10; death before ED arrival; EMS O2 saturation-“sat”<11%; EMS SBP less than 40 or greater than 200; missing sat (5.4% of cases) or SBP (3.1% of cases)]. The relationship between mortality and HOx (sat <90) and/or HT (SBP<90) was assessed with crude and adjusted odds ratios (cOR, aOR) using multivariable logistic regression, controlling for important confounders (see Figure) and accounting for clustering by Trauma Center. RESULTS: 9194 cases were included [Median age: 46 (IQR: 26-65); Male: 68.1%]. 8109 (88.2%) had no HOx/HT, 535 (5.8%) had HOx only, 419 (4.6%) had HT only, and 131 (1.4%) had both HOx/HT. The Figure shows the cORs and aORs for death. CONCLUSION: In this large analysis of major TBI, prehospital HOx and HT were associated with significantly increased mortality. However, the combination of HT and HOx together had a profoundly-negative effect on survival even after controlling for significant confounders. In fact, the aOR for death in patients with both HOx/HT was more than 3 times greater than for those with HOx or HT alone. Since the TBI Guidelines emphasize the prevention and treatment of HOx and HT, their implementation has the potential to significantly impact outcome.