Value of Home Infant Monitors Questioned

Devices don't uncover SIDS risks, study shows

TUESDAY, May 1 (HealthScout) -- A new study suggests that home monitors designed to catch heart and breathing problems may be of little if any value in preventing sudden infant death syndrome (SIDS).

The study shows that while mild pauses in breathing and slowed heart rate are common during infant sleep, only premature babies are at increased risk of severe events associated with the deadly syndrome. However, the study found these episodes don't appear likely to precede SIDS.

The study appears in the May 2 issue of the Journal of the American Medical Association.

An estimated 200,000 premature infants a year are sent home with baby monitors, at a cost of roughly $24 million. The devices track sleep apnea and subdued heart rate, or bradycardia, two conditions once thought to be potential risk factors for SIDS.

But in the last decade, pediatricians have learned that most SIDS cases are the result of improper sleeping position, especially stomach sleeping, and that the incidence of SIDS can be mostly prevented by putting babies to bed on their backs.

"If sleep position and infant bedding are appropriate, there should not be much SIDS left to try to prevent with home monitors," writes Dr. Alan Jobe, a pediatrician at Children's Hospital Medical Center in Cincinnati, in an editorial accompanying the journal article. "Furthermore, the residual causes of SIDS are unlikely to be prevented by home monitoring."

Jobe argues that the new study "justifies a severe curtailing" of the technology. In 1986 the National Institutes of Health recommended home monitoring for babies at high risk of SIDS.

Called the Collaborative Home Infant Monitoring Evaluation (CHIME), the study looked at whether certain infants at high risk for SIDS are more likely to have alarming heart and breathing episodes during sleep than otherwise healthy babies.

The researchers gave specially modified home monitors to the parents of 1,079 infants born between 1994 and 1998. Of those, 306 were born healthy at full term. The rest fell into six other groups considered at high risk of SIDS, including premature babies, those with a sibling who died of the syndrome and those who'd already an apparent life-threatening event (ALTE) of apnea or slowed heart rate.

Over six months, the monitoring machines recorded 6,993 heart and breathing episodes in 445, or 41 percent, of the infants.

Of those, 653 events in 116 infants were considered extreme, based on the length of breathing pauses or how slow their heart rates became, and were similar across all seven groups. Full-term children with a history of ALTEs did not appear to be more at risk of additional events.

Cardiorespiratory episodes were more likely to occur in premature babies, but only until they reached about 11 months of age, far earlier than the peak age for SIDS in most babies, experts say.

Six babies died of sudden, mysterious causes, two of which were diagnosed as SIDS, and none of which occurred when the babies were hooked up to their monitors. One death, involving a baby with two siblings who died of SIDS, was later determined to be a homicide. Murder is believed to account for between 2 percent and 5 percent of apparent SIDS cases.

Dr. Carl Hunt, a member of the research team who now directs the National Institutes of Health's Center on Sleep Disorders Research, says conventional home monitors can only measure episodes of broken breathing, not periods when a baby is trying to breathe but can't. Yet, Hunt says the latter cases may be more important for determining SIDS risk.

Seventy percent of the apnea episodes involved at least three obstructed breaths, the researchers say.

Hunt says the study wasn't designed to test whether monitors save lives, so it's not clear that more babies wouldn't have died of SIDS had the devices not be in place. But he says that question remains "an enigma."

"There are no data to say that using a home monitor in any given infant will prevent sudden infant death syndrome," he says.

Hunt says the findings should help researchers fine-tune their knowledge of home monitors and the significance of extreme events. "One of the things that still needs to be done is a more detailed analysis looking at kids with multiple extreme events," he says.

What To Do

Hunt says putting infants to sleep on their back and not their stomach or side reduces the risk of SIDS dramatically. Since the Back to Sleep Campaign began in 1992, the rate of SIDS in this country has fallen to 0.7 cases per 1,000 live births, a 40 percent drop, he says.

The risk of SIDS declines significantly after a baby reaches six months of age, but it doesn't disappear completely. Another strategy to reduce the chances of sudden death is to make sure the child's bed is free of blankets, quilts and other soft objects that could pose a suffocation threat.

To learn more about SIDS, try the American SIDS Institute or the National SIDS Resource Center.

Read other HealthScout articles about SIDS.

SOURCES: Interview with Carl Hunt, M.D., director, National Center on Sleep Disorders Research, National Heart, Lung and Blood Institute, Bethesda, Md.; May 2, 2001 Journal of the American Medical Association
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