"We speculate that this therapy lowers the brain temperature as well as body temperature and slows down the injury process caused by birth asphyxia, which results in loss of oxygen to the brain," said Yale researcher Richard A. Ehrenkranz, M.D., professor of pediatric neonatology and obstetrics and gynecology at Yale School of Medicine and Yale-New Haven Hospital. "Less injury means a better outcome and fewer cases of cerebral palsy and other complications."
Ehrenkranz co-authored the study with colleagues at 14 other institutions in the National Institute of Child Health and Human Development Neonatal Research Network.
Hypoxic ischemic encephalopathy (HIE) occurs when an infant's brain fails to receive sufficient oxygen or blood before birth. The condition may occur hours before birth or during labor and delivery. It can be caused by complications such as compression or tearing of the placenta or the umbilical cord and rupture of the uterus. Many infants who survive HIE experience brain disability.
The team, led by Seetha Shankaran, M.D., at Wayne State University studied the effect of hypothermia or reduced body temperature, in full-term infants with asphyxia and related complications at birth. Researchers randomly assigned 208 infants to either a control group or a whole-body cooling group where their body temperature was kept at 92.3 degrees for 72 hours, then slowly re-warmed. Body temperatures were lowered by placing babies on a blanket initially filled with circulating 41-degree water. Both groups received standard newborn intensive care including monitoring of vital signs.
When the infants were examined to assess their outcome at 18 to 22 months of age, 44 percent of those in the group treated with hypothermia developed a moderate to severe disability or had died, as compared to 62 percent in the control group.
The Neonatal Research Network will also follow both groups of children until they reach age six or seven, to compare the incidence of health problems or learning difficulties.
Citation: New England Journal of Medicine 353; 15 (October 13, 2005)