Study raises questions about relationship between sudden infant death syndrome and events detected by home monitors
New Haven, Conn. – The use of home monitors to detect prolonged cessation of breathing or a slower than normal heart rate in infants are not an effective means of preventing sudden infant death syndrome (SIDS), a study by a Yale researcher has found.
"This study certainly calls into question the utility of home monitoring for SIDS," said George Lister Jr., M.D., professor of pediatrics and anesthesiology at Yale School of Medicine and chairman of the study group that published its findings this week in the Journal of the American Medical Association.
It has long been held that episodes of prolonged cessation of breathing (apnea) or slowing of the heart rate in infants (bradycardia) had a high risk of evolving into SIDS. For that reason, many infants have been sent home from the hospital with home monitors that trigger an alarm should the infant experience apnea or bradycardia.
The National Institutes of Health authorized a large-scale study to explore the utility of home monitors in preventing SIDS. The monitors are commonly used in early infancy, when there is the highest risk for SIDS.
"This is the first large, longitudinal study comparing incidence of cardiorespiratory events among infants (considered at risk for SIDS) monitored at home with that of healthy term infants," the researchers said. "Based on more than 700,000 hours of monitor use, we determined that events previously described as ‘pathologic’ are actually quite common, even in healthy term infants."
The study included 1,079 infants, among them healthy infants and infants considered at higher than normal risk for SIDS. The infants at high risk were born prematurely, had a sibling who died of SIDS, or had experienced a life-threatening event that required intervention, such as mouth-to-mouth resuscitation or vigorous stimulation.
The infants were monitored for a period of 16 weeks to 66 weeks.
"The thresholds for an ‘event’ conventionally used for home monitoring picked up so many infants that it would be hard to separate those who are normal and not normal," Lister said.
Researchers then set up a specially designed monitor that recorded and saved breathing and heart rate patterns around the time of an "event." The group also examined events that were more severe, that is, they lasted longer than those commonly recorded for usual medical purposes.
"We saw a very high frequency of episodes that would usually be detected, however, the more extreme events occurred almost exclusively in premature infants," Lister said. "The difference in when extreme events most commonly occurred and when SIDS is most likely to occur suggested to us that these events are not immediate precursors to SIDS, as was once thought. These early episodes might be markers of vulnerability to SIDS, but are unlikely to be events that directly evolve into SIDS."
Other researchers involved in the study were Rangasamy Ramanathan, M.D., and Thomas Keens, M.D., the University of Southern California School of Medicine; Michael Corwin, M.D., L. Adrienne Cupples, and Mark Peucker, Boston University Schools of Medicine and Public Health; Carl Hunt, M.D., and David Hufford, M.D., the Medical College of Ohio; Larry Tingsley, M.D., and David Crowell, the University of Hawaii at Manoa; Terry Baird, M.D., Richard Martin, M.D., and Michael Neumann, Case Western Reserve University School of Medicine; Jean Silvestri, M.D., and Debra Weese-Mayer, Rush Medical College, and Marian Willinger, National Institute of Child Health and Human Development.