New technique saves infants

Through the manipulation of body temperatures that may seem unsafe, physicians have been able to use a technique to save newly-born infants that suffer from oxygen depletion.

In a finding published last week in the New England Journal of Medicine, researchers at Yale and at 13 other sites in the Neonatal Research Network found that infants born with severe oxygen loss to the brain have a greater chance of survival if their body temperature is lowered four degrees Fahrenheit for 72 hours. The rate of mortality among these infants decreased from 62 percent to 44 percent when the infants received the cooling treatment within six hours after birth.

“This is what we would call a statistically significant reduction,” said Seetha Shankaran, the study’s lead researcher at the Children’s Hospital of Michigan. “This is a very significant study because it’s the first one that shows that using cold-body cooling does decrease the rate of death and disability.”

Babies born with a severe lack of oxygen and lack of blood flow going to the brain at birth, a condition called hypoxic ischemic encephalopathy (HIE), have a high risk of dying or developing neurological and developmental handicaps such as cerebral palsy later in life, Shankaran said.

She said HIE is not very common, but the condition affects one out of every 1,000 newborns.

Yale School of Medicine professor Richard Ehrenkranz, who led the study at the University, said the study also showed a nine percent decline in the proportion of babies affected with cerebral palsy 18 months after the study.

“Though it’s still early, we’re pleased that our results at this point indicate benefits,” Ehrenkranz said.

Shankaran said the 208 infants selected for the study had to meet several stringent requirements. The babies were all delivered at full term and exhibited very low blood pH levels, which Shankaran said reflects the extent of blood and oxygen supply loss to the whole body. In addition, the cause of the infants’ HIE must have occurred during the course of labor or at delivery, due to such complications as the umbilical cord wrapping around the neck or the placenta separating, she said.

Half of the infants received the standard treatment for HIE while the other half had their body temperatures cooled to 92 F (33.5 C) for 72 hours.

Doctors lowered the infants’ body temperature by placing the babies on a cooling blanket made of soft plastic filled with circulating cold water, monitoring them with a thermometer placed inside their esophagus and attached to a computer system. After 72 hours, researchers slowly rewarmed the babies to a normal body temperature, Shankaran said.

The treatment, known as whole-body hypothermia, has been used successfully in the past, such as during cardiac surgery and cases of head trauma to protect the brain from injury, Ehrenkranz said. These patients usually reach a body temperature of around 26 to 28 C.

“I’m not sure anybody really understands the mechanism of that,” Dr. Jon Tyson, professor of medicine and public health at the University of Texas-Houston Medical School, said. “It’s been known for a long time that children who have fallen through the ice in the winter can survive without breathing for longer periods if they’re cool than if they’re warm.”

Tyson said the cooling may slow the flow of toxic metabolic by-products to the brain, decreasing neurological injury.

Despite the study’s results, Ehrenkranz said the researchers do not plan to extend the whole-body hypothermia treatment to other hospitals due to the complicated nature of the procedure and the possibility of side-effects.

“One of the things you often worry about when you do interventions in the perinatal period is that you might reduce death but also increase handicapping among survivors,” Tyson said. “It’s gratifying in this study that not only did the evidence suggest a reduction in mortality, but among survivors, there tended to be a reduction in survivors with cerebral palsy.”

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