May 16, 2010
BIRMINGHAM, Ala. - New findings in a study led by the director of the University of Alabama at Birmingham (UAB) Division of Neonatology reveal that lowering the oxygen saturation of premature babies' blood decreased the likelihood that an infant would develop severe eye damage, but also increased the chance a neonate would die before discharge.
The study results will be presented May 16 at the American Thoracic Society 2010 International Conference in New Orleans and simultaneously published online by the New England Journal of Medicine.
Retinopathy of prematurity (ROP) is a leading cause of blindness and other visual disabilities in preterm infants. Higher levels of oxygen given to preemies to help them breathe have been linked to an increase in the risk of ROP. Previous studies have suggested that the incidence of ROP is lower in preterm infants who were exposed to reduced levels of oxygenation. However, none of the previous studies have looked at the range of oxygen saturation sufficient to minimize ROP without increasing adverse outcomes, including neonatal mortality.
Waldemar A. Carlo, M.D., professor of pediatrics and Edwin M. Dixon Chair in Neonatology at UAB, and colleagues in the Surfactant, Positive Pressure, and Oxygenation Randomized Trial (SUPPORT), assessed the likelihood that reduced oxygen levels would enable infants to remain healthy and reduce the risk for ROP.
Some 1,316 infants who were born between 24 weeks zero days and 27 weeks six days of gestation were randomly assigned one of two oxygen levels - a lower level of 85 to 89 percent oxygen saturation or the higher level of 91 to 95 percent. Infants also were randomly assigned to continuous positive airway pressure (CPAP) or intubation and surfactant for oxygen delivery.
The primary outcomes the researchers evaluated were severe retinopathy of prematurity, death before discharge from the hospital or both. No overall difference emerged among the groups for this measure. However, a striking difference was revealed when survival and likelihood of experiencing ROP were considered separately.
More infants on the lower-saturation oxygen died than did infants on the higher level -19.9 percent compared to 16.2 percent; but, among those who survived, fewer on the lower saturation developed ROP, 8.6 percent versus 17.9 percent.
"Many doctors believe that optimal oxygen-saturation levels fall between 85 and 95 percent," Carlo said. "The increase in mortality is a major concern, since a lower target range of oxygen saturation is increasingly being advocated to prevent retinopathy of prematurity.
"The results of our study show caution should be exercised regarding a strategy of targeting oxygen-saturation levels in the low range for preterm infants, since it may lead to increased mortality," he said. "Health-care providers should try to prevent both too high and too low levels of oxygen saturation levels to optimize survival without retinopathy."
Carlo added that longer follow-up of these neonates will be required to determine the effects of lower target ranges of oxygen saturation on functional visual and neurodevelopmental outcomes.
The study was conducted as part of the Neonatal Research Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
About the UAB Department of Pediatrics and Division of Neonatology
The UAB Department of Pediatrics and UAB Division of Neonatology, together with Children's Hospital of Alabama, operate the state's only Level IIIC Regional Neonatal Intensive Care Unit (RNICU) and provide the state's highest level and most comprehensive care for well newborns and preterm and term babies with medical conditions. In addition to the RNICU, UAB also is home to a Continuing Care Nursery (CCN), providing extended step-down care for premature infants and infants with medical conditions. UAB is one of the original eight National Institute of Child Health and Human Development (NICHD) research sites commissioned in 1986 and is the only facility in the country that is involved in all three of the NIH research initiatives for maternal, child and family health, the Neonatal Research Network, Maternal-Fetal Medicine Units Network and the Global Network for Women and Children Research.