Hypotension does not increase mortality in brain-injured patients more than it does in non-brain-injured patients

Objectives: Hypotension increases mortality after all types of injuries. Prior studies comparing mortality of hypotensive traumatic brain injury (TBI) patients to normotensive TBI patients have implied that hypotension is particularly detrimental after TBI. It is unknown whether hypotension affects TBI patients more severely than it affects other types of patients. We hypothesized that hypotension does not increase mortality in TBI patients more than it does in non-TBI patients. Methods: National Trauma Data Bank (1994-2002) patients aged 18 to 45 years with blunt mechanisms of injury treated at Level I and Level II centers were included. Deaths occurring before 24 hours were excluded. Logistic regression was used to measure the association between hypotension (≤90 mm Hg) and death after adjusting for confounding variables of age, gender, comorbidities, complications, Glasgow Coma Scale score, and severity of associated injuries. Odds ratios (95% confidence interval) indicate the risk of death in hypotensive patients in each group compared with normotensive patients in the same group. Results: The study population consisted of 79,478 patients (TBI, 30,742; no TBI, 48,736). Hypotension independently quadrupled the risk of death after adjusting for confounding variables (odds ratio [OR], 4.8; 95% confidence interval [CI], 4.1-5.6). However, increase in this risk associated with hypotension was the same in TBI (OR, 4.1; 95% CI, 3.5-4.9) and non-TBI patients (OR, 4.6; 95% CI, 3.4-6.0). Furthermore, the relationship between hypotension and TBI did not change with increasing head Abbreviated Injury Scale score severity. Conclusion: Hypotension is an independent risk factor for mortality. However, it does not increase mortality in TBI patients more than it does for non-TBI patients.