Early modifiable factors associated with fatal outcome in patients with severe traumatic brain injury: A case control study

Objective. Survival of patients with severe traumatic brain injury may be improved by minimizing secondary brain injury. We aimed to identify potentially modifiable contributors to secondary brain injury that may persist and adversely affect patient outcome. Design: Retrospective case control study. Nonsurviving patients with traumatic brain injury were selected and matched 1:1 for age, Glasgow Coma Scale score, Abbreviated Injury Scale: Head (AIS(HEAD)), Revised Trauma Score, and Injury Severity Score with survivors. Potentially modifiable contributors to secondary brain injury were examined and compared in both groups. Setting. A level I trauma center in Melbourne, Australia. Patients: Patients with traumatic brain injury caused by blunt trauma with an AIS(HEAD) >= 4 were identified from a prospective intensive care database. Interventions: None. Measurements and Main Results. Between January 1, 1999, and July 30, 2000, 74 patients, including 37 nonsurvivors, were identified. By design, the groups were well matched for injury severity and baseline conditions. In nonsurvivors, mean arterial pressure was similar to that of survivors at hospital arrival but was lower at 4 hrs after arrival (71 +/- 16 vs. 80 +/- 15 mm Hg, p =.016). A mean arterial pressure <= 65 mm Hg during this 4-hr period was associated with a four-fold increase in the odds of nonsurvival (95% confidence interval, 1.25-12.8). Intracranial pressure monitoring and intensive care unit admission tended to be initiated later in nonsurvivors, potentially delaying recognition and management of inadequate cerebral perfusion pressure. In nonsurvivors, hypothermia did not normalize during the first 24 hrs after injury. Conclusions: In patients with severe traumatic brain injury, lower blood pressure in the first 4 hrs after admission was associated with mortality and may have increased the rate of secondary brain injury. Outcomes of patients with severe traumatic brain injury may potentially be improved by early targeting of the higher mean arterial pressure observed in survivors (mean arterial pressure 80 mm Hg), which may facilitate improved cerebral perfusion. Slower initiation of intracranial pressure monitoring and of intensive care unit admission may also have adversely affected outcomes, whereas persistent hypothermia was associated with nonsurvival.