Cooling Newborns May Help Prevent Brain Damage

Whole-body hypothermia can reduce effects of oxygen deprivation, study suggests

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By Serena Gordon
HealthDay Reporter

WEDNESDAY, Oct. 12, 2005 (HealthDay News) -- Cooling the whole-body temperature of babies whose brains have suffered oxygen deprivation may prevent the brain damage or death that often results from such deprivation, a new study suggests.

Fortunately, severe oxygen or blood deprivation doesn't happen often in infants. When it does, it's called hypoxic-ischemic encephalopathy (HIE), and the damage that results can be similar to that of a stroke. Out of every 1,000 births in the United States, HIE occurs in about 1.5 to two births. An infant with moderate encephalopathy has a 10 percent risk of death, and a 30 percent risk of disability.

Unfortunately, because the cause of HIE is rarely known, there's not much that can be done to treat this problem.

However, medically induced hypothermia reduced the risk of death by 13 percent and the risk of cerebral palsy by 11 percent, according to the new study that appears in the Oct. 13 issue of the New England Journal of Medicine.

"This study was planned because we knew the outcome for infants with moderate to severe encephalopathy was not good," said study co-authors Dr. Seetha Shankaran, director of neonatal and perinatal medicine at Wayne State University School of Medicine, in Detroit.

"There's a high mortality rate and a high rate of handicap among the survivors. Even though we have improved the way we take care of sick infants, we didn't have a treatment to help reduce the risk of brain injury," she said.

For the study, Shankaran and her colleagues enrolled 208 newborns with moderate to severe HIE. The infants were from medical centers across the United States, and all were less than 6 hours old.

The babies were randomly assigned to either the hypothermia group or a control group.

Babies in the hypothermia group were placed on cooling blankets, and their body temperature was lowered to about 92.3 degrees Fahrenheit for 72 hours. While they were being cooled, the babies' heart rates and blood pressure were continuously monitored. The researchers also checked for skin changes.

Eighteen to 22 months later, the babies were all reassessed for neurological disabilities.

Twenty-four percent of infants in the hypothermia group died during the study, compared to 37 percent in the control group.

The incidence of cerebral palsy, a potential complication from HIE, was 19 percent in the hypothermia group, compared to 30 percent in the control group. Blindness occurred in 7 percent of the hypothermia group vs. 14 percent of the control group. Severe hearing impairment was present in 4 percent of the hypothermia group compared to 6 percent of the control group.

There were no significant adverse effects caused by the hypothermia, according to the study.

Shankaran said the researchers don't know exactly why hypothermia appears to be effective, but noted that it slows down many of the processes that can lead to permanent brain damage, such as energy metabolism and cell death in the brain.

Dr. Lu-Ann Papile, a neonatologist at the University of New Mexico School of Medicine, said the study's results are "intriguing and promising," but more studies need to be done to confirm the findings.

In an editorial in the same issue of the journal, Papile pointed out that a study from the Feb. 19, 2005, issue of The Lancet looked at the same issue, but had different results. In that study, just the babies' brains were cooled -- although cooling was initiated a little bit later, and the babies may have had more severe damage. Papile acknowledged that those factors may account for the different findings. Still, she said, these differences point to the need for further research to see if there truly is a benefit to cooling.

"This study is promising, but very preliminary," said Papile. "My concern is that people may say, 'Well why not try this treatment, it might help.' But, these studies were done under very careful settings." And, she added, there is a potential for complications from the treatment. Hypothermia can induce dangerous heart-rhythm irregularities, increase pulmonary artery pressure, and cause direct injury to the skin, she said.

"The nature of neonatology is to try to do something," said Papile. But, she said this treatment just isn't something that should be attempted at community hospitals just yet.

Shankaran said the investigators produced guidelines for the treatment that will be published soon.

"This is a promising treatment that can be offered to families, but only within the very same criteria that we used for this study. This should not be utilized in hospital settings that cannot do it following the published protocol," she said.

More information

While there's no known way to prevent hypoxic ischemic encephalopathy, the U.S. Centers for Disease Control and Prevention has information on steps you can take to have a healthy pregnancy.

SOURCES: Seetha Shankaran, M.D., professor, pediatrics, and director, neonatal and perinatal medicine, Wayne State University School of Medicine/Children's Hospital of Michigan and Hutzel Women's Hospital, Detroit; Lu-Ann Papile, M.D., neonatologist and professor, pediatrics, University of New Mexico School of Medicine, Albuquerque; Oct. 13, 2005, New England Journal of Medicine

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