Prolonged Hypothermia May Improve Outcome of Brain Injury Patients

The National Institutes of Health recently awarded a neurosurgeon at The University of Texas Medical School at Houston $15.6 million to lead a study of prolonged hypothermia's effects on patients with severe brain injury.

Guy L. Clifton, M.D., chairman of the department of neurosurgery and developer of the hypothermia therapy for brain injury, will test whether maintaining a cool body temperature in brain injury patients who already are hypothermic when they are brought to the hospital substantially improves their outcome.

"Current management for patients with traumatic brain injury is unsatisfactory," said Clifton, who holds the Runnells Distinguished Chair in Neurosurgery. "We have to find something that improves outcome. In a previous study, this seemed to work, and now we need to examine it more closely."

In the first National Acute Brain Injury Study, which began in 1994, Clifton found that inducing hypothermia in patients with severe head trauma does not have the therapeutic value that scientists expected.

However, 30 percent of patients in that study were already hypothermic when they came to the emergency room. In that group, maintaining hypothermia appeared to improve outcome. Forty-eight percent of those patients who were kept cold for a period of time had a good outcome and were able to live independently. By contrast, only 24 percent of the hypothermic patients who were re-warmed had a significant recovery. The results of the five-year study were published in the February 2001 New England Journal of Medicine.

With the recent NIH grant, Clifton will expand on that research. He expects to begin enrolling patients this fall.

Patients must be 16 to 45 years old, have a closed head injury and hypothermia, and be comatose upon arrival at an emergency room. They also must have no other significant injuries. Half will be placed in temperature-controlled suits, which were invented and designed by UT-Houston researchers.

The "Rap Round" suits, manufactured by Gaymar Industries, allow doctors to precisely control and maintain patients' body temperatures at 33 to 37 degrees Celsius. After 48 hours, doctors will gradually re-warm the patients over an 18-hour period.

The other patients will re-warm by themselves, with no medical intervention to raise their body temperature.

"We believe that rapid re-warming, which is currently the standard of treatment, may actually be toxic to the brain," Clifton said. "We will be looking at whether it is better to let them passively re-warm or maintain hypothermia."

Because patients must be enrolled in the study before they begin to re-warm, Clifton said, researchers plan to waive informed consent if a family member cannot be located within one hour of the patient's arrival at the hospital. To be in compliance with federal law, researchers are making presentations in the community to inform residents about the study and explain the waiver-of-consent issue.

"The first National Acute Brain Injury Study was the test case for whether waiver of consent was effective and whether the community approved of it," Clifton said. "We showed that it was effective and that the community does approve."

Roughly 1.5 million Americans suffer traumatic brain injury each year. About 50,000 die and another 80,000 of these patients are permanently disabled. An average of 30 percent of those patients are hypothermic when they arrive at the hospital. Hypothermia often is the result of cold weather, intoxication, small body type or cold intravenous fluids that are administered in the field.

"If this works, this could have a tremendous benefit to patients who might otherwise be dead, comatose or severely disabled," Clifton said.

Other investigators in the hypothermia study are at the University of California at Davis, the University of California at San Francisco, the University of Southern California, the University of Pittsburgh Medical Center, Saint Louis University, Duke University, Inova Fairfax Hospital, and the University of Mississippi.

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©2006 Texas Medical Center

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