Cooling May Not Help Injured Brains in Children
Experts say it's too soon to judge this therapy for traumatic brain injury
By Serena Gordon, HealthDay Reporter
Experts say it's too soon to judge this therapy for traumatic brain injury.
WEDNESDAY, June 4 (HealthDay News) -- Cooling the brain after a traumatic brain injury may not help improve neurological outcomes and might even increase mortality.
That's the conclusion of a randomized trial of 225 children with brain injuries, but the authors and other experts suspect that by changing the cooling and re-warming protocol, other researchers may have more success with this therapy.
"Our hypothesis was that hypothermia would improve the outcome," said study author Dr. Jamie Hutchison, a critical care physician and director of the acute care research unit at the Hospital for Sick Children in Toronto.
"Children were randomized to receive 24 hours of cooling, to 32 degrees Celsius. They had to be enrolled within eight hours of their injury and, after cooling, we re-warmed an average of 0.5 degree Celsius every two hours. To our surprise, we didn't see any benefit," said Hutchison.
He said the study was designed to assess neurological outcomes, and that there was no difference between those who were cooled and those who received standard treatment. Additionally, the researchers saw a trend toward increased mortality in the cooled group. But, Hutchison said, the study wasn't designed to assess mortality and that those findings were not statistically significant.
Results of the study are in the June 5 issue of the New England Journal of Medicine.
Youngsters up to age 4 are among those most likely to suffer a traumatic brain injury, according to the U.S. Centers for Disease Control and Prevention. About 435,000 American children visit emergency rooms with traumatic brain injuries each year, and as many as 2,685 children die from traumatic brain injuries in the United States annually, according to the CDC.
Common causes of traumatic brain injuries are motor vehicle accidents, falls, assaults and collisions, like those that might occur during sports, reports the CDC. About 75 percent of traumatic brain injuries are mild, but more serious injuries can cause lifelong disability, creating problems with thinking, reasoning, the senses, language and emotions.
Hutchison said there may be a number of reasons why they didn't see an effect from cooling in the current trial. "Possibly, we may need to keep it going longer after a brain injury, because the brain keeps swelling for days after an injury. Perhaps 24 hours is too short a duration," he theorized.
Also, he said that there was a significantly higher incidence of low blood pressure during re-warming, and that the re-warming period may have been too quick.
The bottom line, said Hutchison, is that cooling for brain injury in children should not be used in the same context it was for this trial: 24 hours of cooling with re-warming occurring over 18 hours.
He said that several other studies of hypothermia for pediatric brain injury are already under way, but they're cooling for longer periods and re-warming more slowly.
Dr. P. David Adelson, director of neurotrauma at Children's Hospital of Pittsburgh, is leading one of the newer trials. He said this was a well-done study, and that other researchers have learned from it, but that "the jury is still out" on hypothermia for brain injury.
In his current study, Adelson said they are starting the cooling sooner, cooling for a longer period of time and re-warming at a far slower pace.
"This is a promising therapy that's going through an evolution. I think this study shows the difficulty of looking at complex disease processes [like traumatic brain injury], and trying to look at interventions. No one therapy will be the end-all treatment for brain trauma," said Adelson.
To learn more about traumatic brain injury, visit the U.S. Centers for Disease Control and Prevention.
Volume 358:2447-2456 June 5, 2008 Number 23
New England Journal of Medicine
Hypothermia Therapy after Traumatic Brain Injury in Children
James S. Hutchison, M.D., Roxanne E. Ward, B.A., Jacques Lacroix, M.D., Paul C. He'bert, M.D., M.H.Sc., Marcia A. Barnes, Ph.D., Desmond J. Bohn, M.B., Peter B. Dirks, M.D., Steve Doucette, M.Sc., Dean Fergusson, Ph.D., Ronald Gottesman, M.D., Ari R. Joffe, M.D., Haresh M. Kirpalani, M.B., M.Sc., Philippe G. Meyer, M.D., Kevin P. Morris, M.D., David Moher, Ph.D., Ram N. Singh, M.D., Peter W. Skippen, M.D., for the Hypothermia Pediatric Head Injury Trial Investigators and the Canadian Critical Care Trials Group
Background Hypothermia therapy improves survival and the neurologic outcome in animal models of traumatic brain injury. However, the effect of hypothermia therapy on the neurologic outcome and mortality among children who have severe traumatic brain injury is unknown.
Methods In a multicenter, international trial, we randomly assigned children with severe traumatic brain injury to either hypothermia therapy (32.5°C for 24 hours) initiated within 8 hours after injury or to normothermia (37.0°C). The primary outcome was the proportion of children who had an unfavorable outcome (i.e., severe disability, persistent vegetative state, or death), as assessed on the basis of the Pediatric Cerebral Performance Category score at 6 months.
Results A total of 225 children were randomly assigned to the hypothermia group or the normothermia group; the mean temperatures achieved in the two groups were 33.1±1.2°C and 36.9±0.5°C, respectively. At 6 months, 31% of the patients in the hypothermia group, as compared with 22% of the patients in the normothermia group, had an unfavorable outcome (relative risk, 1.41; 95% confidence interval [CI], 0.89 to 2.22; P=0.14). There were 23 deaths (21%) in the hypothermia group and 14 deaths (12%) in the normothermia group (relative risk, 1.40; 95% CI, 0.90 to 2.27; P=0.06). There was more hypotension (P=0.047) and more vasoactive agents were administered (P<0.001) in the hypothermia group during the rewarming period than in the normothermia group. Lengths of stay in the intensive care unit and in the hospital and other adverse events were similar in the two groups.
Conclusions In children with severe traumatic brain injury, hypothermia therapy that is initiated within 8 hours after injury and continued for 24 hours does not improve the neurologic outcome and may increase mortality. (Current Controlled Trials number, ISRCTN77393684 [controlled-trials.com] .)
The affiliations of the authors are listed in the Appendix.
Address reprint requests to Dr. Hutchison at the Department of Critical Care Medicine, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada, or at email@example.com.
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