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New study contradicts earlier results on cooling for brain injury
Thursday, February 22, 2001 By Anita Srikameswaran, Post-Gazette Staff Writer
If your brain has been injured, being cool doesn't matter much.
A new study has found that patients with traumatic brain injury who were cooled a few degrees below normal body temperature did not fare any better than those who didn't undergo hypothermia.
That contradicts results from previous smaller studies that suggested cooling the brain-injured meant a greater likelihood of complete recovery.
In the new research, similar percentages of people died or were severely impaired from the injuries regardless of the use of hypothermia. The findings were published in today's New England Journal of Medicine.
Dr. Guy Clifton of the University of Texas-Houston, who led the study, said researchers shouldn't give up just yet.
"Many of us thought this treatment would probably work once we figured out how to do it, and I still think it can work," he said. "We've learned from this study and I think we have very strong data."
In this trial, too much time may have passed between the injury and the actual cooling, diminishing its effect, Clifton explained. More research is justified, he added.
Animal experiments and previous human studies, including a 1997 study of 82 patients that was led by Dr. Donald Marion, director of the University of Pittsburgh's Brain Trauma Research Center, indicated that cooling the body, and hence the brain, decreased brain swelling after injury and improved outcome.
But hypothermia required testing in more patients before definitive conclusions could be drawn.
The recent study, which began in 1994, included almost 400 patients from around the country. Marion led the local arm of the 11-center trial.
About four hours after they were injured, patients were randomly assigned to either be cooled or get standard treatment.
The cooling process took an average of eight hours by using ice packs and flushing the stomach with cold fluids. Body temperature was maintained at 91.4 degrees for 48 hours, and then the patient was carefully warmed up to normal.
In each group, 57 percent of the patients suffered severe disability, a vegetative state or death. Twenty-seven percent of the patients in the standard treatment group and 28 percent of the hypothermia group died. In patients who recovered, there was no difference between the groups in neurological, behavioral and psychological testing six months later.
A breakdown of the data shows that people older than 45 who undergo cooling tend to do worse than their counterparts in the standard treatment group.
Also, patients who arrive at the hospital already hypothermic don't need to be warmed to normal body temperature and perhaps shouldn't be. Those already cool patients tended to have more damage than patients who initially had normal temperatures, suggesting that a severe injury causes the body to cool down, the researchers said.
"It might be a protective response," Clifton said.
The next research step would be to randomize brain-injured people who are already hypothermic to have either their low body temperature maintained or passively warm them up and then compare the outcomes.
The cooling may not have happened quickly enough after the injury to make an impact, noted Dr. Raj Narayan, of Temple University School of Medicine, in a commentary accompanying today's report. In the study, it took an average of 8 1/2 hours from the time of injury to reach the target temperature of 91.4 degrees.
He also pointed out that the research could not have been done if federal overseers hadn't allowed informed consent to be waived for some patients.
"This option is important for study of conditions such as traumatic brain injury and cardiopulmonary arrest, in which the patient obviously cannot give consent and the family is often not available," Narayan wrote.
Brain trauma isn't the only neurological event that researchers suspect might be better treated with cooling. Last week, for instance, at a Fort Lauderdale meeting of the American Stroke Association, a group of scientists from the Cleveland Clinic presented results from a small study that indicated cooling benefited patients who had suffered strokes.
That study primarily showed that cooling could be safely done in stroke patients, but there's a long way to go before effectiveness can be considered proven, Clifton said.
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