Cooling Unresponsive Newborns
May Reduce the Risk of Death

Cooling unresponsive newborns within hours of birth reduces their risk of death or disability, an article in Thursday's New England Journal of Medicine reports.

The results build on increasing evidence from animal studies and some small human trials that show that controlled lowering of the body's temperature after injury has a protective effect. In adults, body cooling, or hypothermia, has been recommended as a treatment after cardiac arrest by medical societies in several countries, based on clinical trials showing a benefit of the technique. Hypothermia also is being studied for the treatment of stroke and brain injury.

Still, Lu-Ann Papile, a pediatrician at the University of New Mexico who wrote an accompanying editorial to the study, says it is important to keep in mind that, while the results are encouraging, the overall number of babies who benefited was small. In babies who were cooled, and those who weren't, the majority went on to have serious complications, she says. She argues the treatment should be considered experimental.

Babies not breathing at birth used to be cooled in the past, mostly in Europe and Russia. However, the practice fell out of favor after studies showed that premature babies did better when warmed.

But interest in the cooling technique for full-term babies has recently rekindled, with several research teams around the world performing randomized clinical trials in babies born unresponsive because not enough oxygen had reached their brain. This happens in about two in every 1,000 births, studies have shown, with 15% to 20% of those babies dying and 20% to 25% ending up disabled.

Lack of oxygen in the brain leads to a "domino effect" of damaging events that include damage to brain cells and swelling, says Marianne Thoresen, a British researcher whose group published the results of a clinical trial of newborn hypothermia earlier this year. "What hypothermia does is stop a lot of the damaging processes, and it's not like they start again when you rewarm," she says. "In a way, everything is calmed down when cooled."

In today's NEJM study, the second large-scale newborn hypothermia trial to be published, babies enrolled in the 15-hospital study had to be full-term, not premature, and show evidence that they were unresponsive as a result of a lack of oxygen to their brain, not another reason, like an infection, says Seetha Shankaran from Wayne State University, the trial's principal investigator. The babies had to be treated within six hours.

Doctors used cooling blankets to lower the babies' temperature to 33.5 degrees Celsius (92.3 degrees Fahrenheit) for 72 hours from around 37 degrees Celsius. "We know from previous experience that below 30 degrees you start seeing complications," says Dr. Shankaran. The babies were slowly warmed after the treatment.

Of the 102 babies who were given the cooling treatment, 44% died or suffered a disability in follow-up tests at a later age, as compared with 62% of the 106 babies who weren't cooled.

Dr. Shankaran and others expressed concern that doctors might prematurely adopt the hypothermia method. Rosemary Higgins, an investigator with the National Institute of Child Health and Human Development, which sponsored the study, says the institute currently is working with the American Academy of Pediatrics to develop recommendations on cooling oxygen-deprived babies.