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Sudden Infant Death Syndrome
Sudden infant death syndrome is the most common cause of post-neonatal infant death in the United States. In 1992, the American Academy of Pediatrics recommended that healthy term infants be placed on their backs to sleep. As a result, a decline in the prevalence of prone infant sleep was associated with declining SIDS incidence.
The prevalence of prone sleeping has since declined from 70% in 1992 to 24% in 1996. In subsequent analyses of 1994-98 trends, the prevalence of prone sleeping declined from 44% to 17% among whites and from 53% to 32% among African Americans.
Controversy remained for a number of years regarding the sleep position for premature and low birth weight infants. Partly out of concern that premature infants might incur special risks from supine sleeping, the initial AAP recommendation did not apply to premature infants experiencing respiratory distress.
Low birth weight infants have a significantly higher risk of SIDS, a risk tightly correlated with prematurity. High SIDS incidence among low birth weight, very low birth weight (VLBW), and extremely low birth weight infants persists despite increased overall survival within these infant populations. Although SIDS incidence has decreased among VLBW infants, SIDS incidence within this population remains much higher than for infants of normal birth weight. The greater risk of SIDS for preterm infants was noted a more recent AAP statement, and the supine sleep position is now explicitly recommended for these infants.
Apnea and bradycardia have long been observed in infants at increased risk for SIDS. Researchers have assumed that if such events can be detected, they can also be interrupted, thereby preventing SIDS. The Collaborative Home Infant Monitoring Evaluation (CHIME) study, which used specially designed electronic monitors in the home to detect such cardiorespiratory events in infants, revealed that this assumption might not be true.
Episodes of prolonged cessation of breathing or prolonged slowing of heart rate in infants -- believed to be potential signs of risk for SIDS -- primarily occur before the developmental age when most SIDS deaths occur, according to a study funded by the National Institute of Child Health and Human Development (NICHD). The findings, appearing in the May 2, 2001, Journal of the American Medical Association, suggest that these events are not necessarily signs of impending SIDS.
?The difference in when extreme events most commonly occur and when SIDS is most likely to occur suggests that these events are not immediate precursors to SIDS, as was once thought," said George Lister, M.D., study group chairman and one of the authors of the JAMA article. "These events might be markers of vulnerability, rather than immediate indicators of SIDS."
The CHIME study followed 1,079 infants during their first six months after birth using electronic home monitors to detect cardiorespiratory events. The infants were classified as either healthy (born at full-term, clinically well, no family history of SIDS in siblings or relatives), or at increased risk of SIDS. The latter group included babies whose risk of SIDS was more than twice their healthy counterparts: preterm or premature babies; siblings of SIDS victims; and those who experienced an apparent life-threatening event (ALTE), defined as an event that required mouth-to-mouth resuscitation or vigorous stimulation.
The home monitors were designed to measure heart rate and breathing patterns including rib cage and abdominal movement and the volume of a breath. Parents were instructed to use the monitors when the baby was sleeping or was not being observed. During 718,358 hours of home monitoring, researchers in the CHIME study found that apnea and bradycardia occurred frequently, even in healthy babies who were born at full-term. However, the most extreme events, those that lasted a very long time by usual medical standards, were common only in infants born prematurely and were found to be associated with significant decreases in blood oxygenation. Most of these extreme events occurred prior to the age when SIDS is most common (between 2 and 6 months of age for full term infants).
These results cast serious doubt on the idea that extreme cardiorespiratory events are immediate precursors of SIDS. In addition, the extreme events were frequently associated with airway obstruction. Home monitors that are currently available for use by parents use methods that would not detect obstructed breathing, which means many of these extreme events might have gone unnoticed.
Researchers stressed that the CHIME study did not address whether home monitoring decreases the incidence of SIDS, nor did it explore whether extreme cardiorespiratory events are markers of vulnerability to SIDS. The June 11, 1998, issue of the New England Journal of Medicine contains a study on the relationship between prolonged QT interval and the occurrence of sudden infant death syndrome (SIDS). The study authors found that infants with a prolonged QT interval had a greater risk of dying as a result of SIDS than did those with normal QT intervals.
The odds ratio of SIDS was 41.3 times greater in infants with a prolonged QT interval than in infants with a normal QT range. The relationship of the QT interval to SIDS has been the subject of investigation for three decades. It is important to note that except for the study cited above, no other studies have shown a clear association between a prolonged QT interval and SIDS, but the identification of strongly associated risk factors could improve screening techniques and would be of great prophylactic benefit in reducing the incidence of SIDS deaths.
Sudden Infant Death Alliance - http://sidsalliance.org/
Research, tips for prevention, support for families, publications, and events.
SIDS International - http://www.sidsinternational.minerva.com.au
Representatives from 17 member countries. Dedicated to the same goals of
solving the mystery of SIDS; providing support for families who have
experienced the death of a child; and educating the community about SIDS.
Foundation for the Study of Infant Deaths (FSID) - http://www.sids.org.uk/fsid/
UK's leading cot death (SIDS) charity, supporting bereaved families, providing
information to the public and funding research into infant health and infant
SIDS Australia Online - http://www.sidsaustralia.org.au
This resource aims to provide information on Sudden Infant Death Syndrome
(SIDS) to a wide variety of people including researchers, health
professionals, parents, school teachers and children.
Arizona SIDS Alliance - http://www.azsids.org/
Dedicated to educating people about Sudden Infant Death Syndrome and how to
reduce the risk, offering assistance to grieving families after the loss of an
infant to SIDS and providing assistance to scientists and medical
SIDS Global Strategy Task Force - http://www.sidsglobal.org
Independent, international group of SIDS researchers, clinicians and
educationalists who are interested in networking their efforts on a global
level to enhance SIDS research and education.
The Angel with the Golden Glow - http://www.angelwiththegoldenglow.com
A children's story about a little angel who shares his story of hope and love.
Offers hope and healing to families dealing with the loss of a child from