Study objective: Out-of-hospital hypotension has been associated with increased mortality in traumatic brain injury (TBI). The association of TBI mortality with the depth or duration of out-of-hospital hypotension is unknown. We evaluated the relationship between the depth and duration of out-of-hospital hypotension and mortality in major traumatic brain injury. Methods: We evaluated adults and older children with moderate or severe TBI in the preimplementation cohort of Arizona's statewide Excellence in Prehospital Injury Care study. We used logistic regression to determine the association between the depth-duration dose of hypotension (depth of systolic blood pressure <90 mm Hg integrated over duration [minutes] of hypotension) and odds of inhospital death, controlling for significant confounders. Results: There were 7,521 TBI cases included (70.6% male patients; median age 40 years [interquartile range 24 to 58]). Mortality was 7.8% (95% confidence interval [CI] 7.2% to 8.5%) among the 6,982 patients without hypotension (systolic blood pressure ≥90 mm Hg) and 33.4% (95% CI 29.4% to 37.6%) among the 539 hypotensive patients (systolic blood pressure <90 mm Hg). Mortality was higher with increased hypotension dose: 0.01 to 14.99 mm Hg-minutes 16.3%; 15 to 49.99 mm Hg-minutes 28.1%; 50 to 141.99 mm Hg-minutes 38.8%; and greater than or equal to 142 mm Hg-minutes 50.4%. Log2 (the logarithm in base 2) of hypotension dose was associated with TBI mortality (adjusted odds ratio 1.19 [95% CI 1.14 to 1.25] per 2-fold increase of dose). Conclusion: In this study, the depth and duration of out-of-hospital hypotension were associated with increased TBI mortality. Assessments linking out-of-hospital blood pressure with TBI outcomes should consider both depth and duration of hypotension.
ASJC Scopus subject areas
- Emergency Medicine