NEW ORLEANS — Though it may seem counterintuitive, β-blockers appear to have a protective effect in trauma patients with head injury and may even improve outcomes, according to two presentations at the annual meeting of the American Association for the Surgery of Trauma.
In the first paper, Dr. Saman Arbabi and colleagues at the University of Washington Harborview Medical Center in Seattle and the University of Michigan in Ann Arbor hypothesized that even though β-blockers might lower cerebral perfusion pressure, they could be safe in trauma patients, including those with head injury.
Dr. Arbabi and associates reviewed outcomes for 4,711 trauma patients from 2001 to 2004, and found that 303, or 7%, were given β-blockers, usually to control blood pressure and heart rate. This group was compared with a control cohort—essentially, all the other trauma patients— who did not receive the drugs. Overall, the mortality rate was 6%, or 230 of the 4,117 patients who were part of the study.
The cause of death in half the group was head injury; cardiac complications were a significant factor in 9% of the deaths. After adjusting for age, injury severity score, blood pressure, Glasgow Coma Score (GCS), respiratory status, and mechanism of injury, the odds ratio for death was lower for patients given β-blockers (odds ratio 0.3), Dr. Arbabi said. The effect of β-blockers was most pronounced in patients who had a GCS of 14 or less (odds ratio 0.2), compared with patients with a GCS of 14–15 (odds ratio 0.5).
In a second paper, Dr. Bryan A. Cotton of Vanderbilt University in Nashville, Tenn., reviewed the trauma registry for all patients with a head Abbreviated Injury Scale (AIS) of 3 or greater and β-blocker exposure of at least 2 days who were admitted from January 2004 to March 2005.
Only patients with a head AIS attributable to traumatic brain injury were included. Pediatric patients were excluded, as were patients who were not managed by the trauma team or whose length of stay was less than 4 days or greater than 30 days.
About 1,200 patients met the inclusion criteria. After exclusions, Dr. Cotton and his colleagues evaluated 420 patients, of whom 173 had β-blocker exposure and 247 did not. There were no significant differences between the two groups, although those exposed to β-blockers did tend to be older, with a mean age of 50, compared with 36 for the unexposed group, he said.
Five percent of the patients who received β-blockers died—a 70% reduction in mortality, compared with the unexposed group after adjusting for age, sex, and injury severity scores, he said. The β-blocker patients did have higher rates of infection—38% vs. 21%—and respiratory complications—70% vs. 47%. And at 11 days, their average length of stay was 4 days longer than for the unexposed group.
But β-blocker exposure was strongly associated with a protective effect, Dr. Cotton said.
Propanolol was the most commonly used β-blocker in both studies, although Dr. Arbabi said that metoprolol would likely be his preference.
Neither institution is using β-blockers under any protocols for head injury patients. Both Dr. Arbabi and Dr. Cotton said that their hypotheses should be confirmed by randomized, prospective studies before physicians proceed with regular use of β-blockers.
In discussing the papers, Dr. Blaine L. Enderson of the University of Tennessee Medical Center, Knoxville, said, “These papers are some of the most exciting of this meeting because of the future avenues of research they present and the potential therapeutic benefit they offer.”
Dr. Enderson agreed that there were many unanswered questions, including which patients should be given the drugs and at what point after injury.
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