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Turning Down the Thermostat May Help Some Baby Brains

Thursday, June 12, 2008 - 11:58
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For decades, hospital nurseries have taken great care to keep babies warm. You can hardly move in the average maternity ward without tripping over incubators, warming bassinets and receiving blankets. Now, though, some hospitals are turning the thermostat down for a few infants.

How come? For babies that didn’t get quite enough oxygen during birth, a lower temperature during their first few days in the world appears to help their brains develop. The temperature drop needed is small — perhaps 33 or 35 degrees Celsius instead of 36 (that’s 91-95 degrees Farenheit vs. 98.6).

But six to 18 months later, the infants that were kept cool show better results on standard tests that involve everything from putting a raisin in a bottle to speaking and leg movement, says Sessions Cole, director of newborn medicine at St. Louis Children’s Hospital. “It works — or at least, we think it works,” Cole told Health Blog when he stopped by for a visit this week. He says that at any given time, about 10 of 75 babies at his facility are chilling out.

Most babies do better warm. But researchers noticed that some babies that received too little oxygen at birth lowered their own body temperature slightly, and did better than similar infants that didn’t, Cole says. So hospitals are starting to cool babies that got came up short on oxygen, in some cases because the placenta separates too soon. St. Louis zeros in on infants with a low 5-minute Apgar score, a test of vital signs.

In 2005 a Lancet study looked at cooling infants’ heads, while a New England Journal of Medicine study looked at whole-body cooling; both got results.

As a result, European and Australian hospitals tend to use cooling caps, while U.S. hospitals seem to be leaning toward cooling blankets like those used in surgery, says Taeun Chang, director of neonatal neurosurgery at Children’s National Medical Center. “From a logistics standpoint, keeping them cool all over is an easier intervention for all hospitals to do,” Cole says.

The mechanism still isn’t clear. Docs can’t go around taking brain biopsies to see what’s going on. But it seems cooling slows the brain’s metabolism and that reduces inflammation and may also reduce seizures as well. Chang likens it to icing a sprained ankle or putting cold water on a burn.

But doctors have been cautious. “The history of taking care of babies is paved with people with good intentions but bad theories,” Cole says, citing a late-1950s practice of giving extra oxygen to premature infants — only to raise the risk of blindness.

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