Cooling Helps Oxygen-Deprived Newborns
Study found it lowered risk of neurological problems later
WEDNESDAY, Sept. 30, 2009 (HealthDay News) -- New research shows that lowering the body temperature of oxygen-deprived newborns reduces the risk for neurological problems later.
Unfortunately, the strategy did not reduce the risk of death or severe disability.
Still, the findings, appearing in the Oct. 1 issue of the New England Journal of Medicine, help fill a crucial gap in the effort to treat babies who have brain damage due to hypoxia, or lack of oxygen.
"This is another bit of incremental evidence that hypothermia helps with hypoxia and ischemia [restriction in blood supply]," said Dr. John Ragheb, a professor of clinical neurological surgery and pediatrics at the University of Miami Miller School of Medicine, who is familiar with the study. "This is going to be a very important paper."
But many institutions already practice cooling in this context, added Dr. James Greenberg, director of the division of neonatology at Cincinnati Children's Hospital Research Foundation, making it uncertain how much the paper is actually going to change current practice.
And there's more that needs to be known, including which newborns would benefit most from the practice, and how best to apply it, he said.
Cooling body temperature, or hypothermia, has been used since the 1920s or 1930s to help with injuries and even to reduce damage after a heart attack, Ragheb noted.
But scientists are only now collecting data on how hypothermia might benefit babies born with hypoxic-ischemic encephalopathy (HIE), when severe blood deprivation to the brain results in the death of brain cells, possibly leading to cerebral palsy or mental retardation.
Previous research has focused on premature babies, Ragheb said. "This is term babies, so it expands the indication for using it."
This study, conducted in five countries, involved 325 babies who were less than six hours old who had been born near-term and who had suffered brain damage as a result of oxygen deprivation.
The newborns were randomized either to intensive care along with cooling of the body to 33.5 degrees Celsius (92.3 degrees Fahrenheit) or to intensive care alone.
Those in the cooling group were swaddled in cooling blankets and placed in incubators without the power on. They were cooled for about 72 hours.
The infants were then followed until they were 18 months old.
Mortality was roughly the same in the two groups: 42 infants in the cooled group died, compared with 44 infants in the control group. The number of infants with severe neurodevelopmental disability was 32 in the cooled group and 42 in the control group.
But babies in the cooled group had a 57 percent increased chance of surviving without neurological damage. This included a 33 percent decreased risk of cerebral palsy as well as improved scores on indices of mental development and psychomotor skills.
Cooling also reduced the rate of multiple neurodevelopmental problems: 21 infants in the cooled group (out of 112 survivors) vs. 33 (out of 110 survivors) in the other group.
Cooling probably works by "slowing down the metabolism of neurons or brain cells in such a way that it prevents them from dying," Greenberg explained.
Surgeons sometimes use severe cooling to stop the heart when performing cardiothoracic surgery in newborns, he added.
The authors, from a consortium of institutions in Britain, pointed out that some effects might not be evidenced until after 18 months of age, but that no study has yet looked this far out.
The Children's National Medical Center has an explanation of whole-body hypothermia.