Correlation between prehospital and in-hospital hypotension and outcomes after traumatic brain injury

Background and objective: Hypotension has a powerful effect on patient outcome after traumatic brain injury (TBI). The relative impact of hypotension occurring in the field versus during early hospital resuscitation is unknown. We evaluated the association between hypotension and mortality and non-mortality outcomes in four cohorts defined by where the hypotension occurred [neither prehospital nor hospital, prehospital only, hospital only, both prehospital and hospital]. Methods: Subjects ≥10 years with major TBI were included. Standard statistics were used for unadjusted analyses. We used logistic regression, controlling for significant confounders, to determine the adjusted odds (aOR) for outcomes in each of the three cohorts. Results: Included were 12,582 subjects (69.8% male; median age 44 (IQR 26–61). Mortality by hypotension status: No hypotension: 9.2% (95%CI: 8.7–9.8%); EMS hypotension only: 27.8% (24.6–31.2%); hospital hypotension only: 45.6% (39.1–52.1%); combined EMS/hospital hypotension 57.6% (50.0–65.0%); (p < 0.0001). The aOR for death reflected the same progression: 1.0 (reference-no hypotension), 1.8 (1.39–2.33), 2.61 (1.73–3.94), and 4.36 (2.78–6.84), respectively. The proportion of subjects having hospital hypotension was 19.0% (16.5–21.7%) in those with EMS hypotension compared to 2.0% (1.8–2.3%) for those without (p < 0.0001). Additionally, the proportion of patients with TC hypotension was increased even with EMS “near hypotension” up to an SBP of 120 mmHg [(aOR 3.78 (2.97, 4.82)]. Conclusion: While patients with hypotension in the field or on arrival at the trauma center had markedly increased risk of death compared to those with no hypotension, those with prehospital hypotension that was not resolved before hospital arrival had, by far, the highest odds of death. Furthermore, TBI patients who had prehospital hypotension were five times more likely to arrive hypotensive at the trauma center than those who did not. Finally, even “near-hypotension” in the field was strongly and independently associated the risk of a hypotensive hospital arrival (<90 mmHg). These findings are supportive of the prehospital guidelines that recommend aggressive prevention and treatment of hypotension in major TBI.