sudden infant death syndrome

Sudden Infant Death Syndrome

 

Definition

Sudden infant death syndrome (SIDS) is the unexplained death without warning of an apparently healthy infant, usually during sleep.

Description

Also known as crib death, SIDS has baffled physicians and parents for years. In the 1990s, advances have been made in preventing the occurrence of SIDS, which killed more than 4,800 babies in 1992 and 3,279 infants in 1995. Education programs aimed at encouraging parents and caregivers to place babies on their backs and sides when putting them to bed have helped contribute to a lower mortality rate from SIDS.

In the United States, SIDS strikes one or two infants in every thousand, making it the leading cause of death in newborns. It accounts for about 10% of deaths occurring during the first year of life. SIDS most commonly affects babies between the ages of two months and six months; it almost never strikes infants younger than two weeks of age or older than eight months. Most SIDS deaths occur between midnight and 8 A.M.

Causes and symptoms

Risk factors for sids

The exact causes of SIDS are still unknown, although studies have shown that many of the infants had recently been under a doctor's care for a cold or other illness of the upper respiratory tract. Most SIDS deaths occur during the winter and early spring, which are the peak times for respiratory infections. The most common risk factors for SIDS include:

• sleeping on the stomach (in the prone position)
• mother who smokes during pregnancy; smokers are as much as three times more likely than nonsmokers to have a SIDS baby
• the presence of passive smoke in the household
• male sex; the male/female ratio in SIDS deaths is 3:2;
• belonging to an economically deprived or minority family
• mother under 20 years of age at pregnancy
• mother who abuses drugs
• mother with little or no prenatal care
• prematurity or low weight at birth
• family history of SIDS

Most of these risk factors are associated with significantly higher rates of SIDS; however, none of them are exact enough to be useful in predicting which specific children may die from SIDS.

Theories about sids

MEDICAL DISORDERS. Currently, it is not known whether the immediate cause of death from SIDS is a heart problem or a sudden interruption of breathing. The most consistent autopsy findings are pinpoint hemorrhages inside the baby's chest and mild inflammation or congestion of the nose, throat, and airway. Some doctors have thought that the children stop breathing because their upper airway gets blocked. Others have suggested that the children have an abnormally high blood level of the chemicals that transmit nerve impulses to the brain, or that there is too much fetal hemoglobin in the blood. A third theory concerns the possibility that SIDS infants have an underlying abnormality in the central nervous system. This suggestion is based on the assumption that normal infants sense when their air supply is inadequate and wake up. Babies with an abnormal nervous system, however, do not have the same alarm mechanism in their brains. Other theories about the cause of death in SIDS include immune system disorders that cause changes in the baby's heart rate and breathing patterns during sleep, or a metabolic disorder that causes a buildup of fatty acids in the baby's system.

PHYSICAL SURROUNDINGS. A recent theory proposes that SIDS is connected to the child's rebreathing of stale air trapped in soft bedding. In addition to the infant's sleeping in the prone position, pillows, sheepskins, and other soft items may contribute to trapping air around the baby's mouth and nose, which causes the baby to breathe in too much carbon dioxide and not enough oxygen. Wrapping a baby too warmly has also been proposed as a factor.

Diagnosis

The diagnosis of SIDS is primarily a diagnosis of exclusion. This means that it is given only after other possible causes of the baby's death have been ruled out. Known risk factors aid in the diagnosis. Unlike the pattern in other diseases, however, the diagnosis of SIDS can only be given post-mortem. It is recommended that all infants who die in their sleep receive an autopsy to determine the cause. Autopsies indicate a definite explanation in about 20% of cases of sudden infant death. In addition, an autopsy can often put to rest any doubts the parents may have. Investigation of the location of the death is also useful in determining the child's sleeping position, bedding, room temperature, and similar factors.

Treatment

There is no treatment for SIDS, only identification of risk factors and preventive measures. The baby's parents may benefit from referral to counseling and support groups for parents of SIDS victims.

Prevention

SIDS appears to be at least partly preventable, which has been shown by a substantial decrease in the case rate. The following are recommended as preventive measures:

• Sleep position. The United States Department of Health and Human Services initiated a "Back-to-Sleep" campaign in 1994 to educate the public about sleep position. Prior to that time, an estimated 70% of infants slept on their stomachs, since parents had been taught that a "back down" position contributed to choking during sleep. There are some conditions for which doctors will recommend the prone position, but for normal infants, side or back (supine) positions are better. When placing an infant on his or her side, the parent should pull the child's lower arm forward so that he or she is less likely to roll over onto the stomach. When babies are awake and being observed, they should be placed on their stomachs frequently to aid in the development of the muscles and skills involved in lifting the head. Once a baby can roll over to his or her stomach, he or she has developed to the point where the risk of SIDS is minimal.
• Good prenatal care. Proper prenatal care can help prevent the abnormalities that put children at higher risk for SIDS. Mothers who do not receive prenatal care are also more likely to have premature and low birth-weight babies. Expectant mothers should also be warned about the risks of smoking, alcohol intake, and drug use during pregnancy.
• Proper bedding. Studies have shown that soft bedding, such as beanbags, waterbeds and soft mattresses, contributes to SIDS. Babies should sleep on firm mattresses with no soft or fluffy materials underneath or around them—including quilts, pillows, thick comforters or lambskin. Soft stuffed toys should not be placed in the crib while babies sleep.
• Room temperature. Although babies should be kept warm, they do not need to be any warmer than is comfortable for the caregiver. An overheated baby is more likely to sleep deeply, perhaps making it more difficult to wake when short of breath. Room temperature and wrapping should keep the baby warm and comfortable but not overheated.
• Diet. Some studies indicate that breastfed babies are at lower risk for SIDS. It is thought that the mother's milk may provide additional immunity to the infections that can trigger sudden death in infants.
• Bedsharing with parents. Opinions differ on whether or not bedsharing of infant and mother increases or decreases the risk of SIDS. Bedsharing may encourage breastfeeding or alter sleep patterns, which could lower the risk of SIDS. On the other hand, some studies suggest that bedsharing increases the risk of SIDS. In any case, mothers who choose to bring their babies to bed should observe the following cautions: Soft sleep surfaces, as well as quilts, blankets, comforters or pillows should not be placed under the baby. Parents who sleep with their infants should not smoke around the baby, or use alcohol or other drugs which might make them difficult to arouse. Parents should also be aware that adult beds are not built with the same safety features as infant cribs.
• Secondhand smoke. It is as important to keep the baby's environment smoke-free during infancy as it was when the mother was pregnant with the baby.
• Electronic monitoring. Electronic monitors are available for use in the home. These devices sound an alarm for the parents if the child stops breathing. There is no evidence, however, that these monitors prevent SIDS. In 1986, experts consulted by the National Institutes of Health (NIH) recommended monitors only for infants at risk. These infants include those who have had one or more episodes of breath stopping; premature infants with breathing difficulties; and babies with two or more older siblings that died of SIDS. Parents who use monitors should know how to use them properly and what to for the baby if the alarm goes off.
• Immunizations. There is no evidence that immunizations increase the risk of SIDS. In fact, babies who receive immunizations on schedule are less likely to die of SIDS.

Resources

Organizations

Association of SIDS and Infant Mortality Programs. MN SID Center, Children's Hospitals and Clinics, 2525 Chicago Ave. So., Minneapolis, MN 55404. (612) 813-6285. http://www.asip1.org.

National Institute of Child Health and Human Development. Bldg 31, Room 2A32, MSC 2425, 31 Center Drive, Bethesda, MD 20892-2425. (800) 505-2742. http://www.nichd.nih.gov/sids/sids.htm.

National SIDS Resource Center. 2070 Chain Bridge Road, Suite 450, Vienna, VA 22181. (703) 821-8955. 〈http://www.circsol.com/SIDS/〉.

Sudden Infant Death Syndrome Alliance. 1314 Bedford Avenue, Suite 210, Baltimore, MD 21208. (800) 221-7437. http://www.sidsalliance.org.

sudden infant death syndrome

 (SIDS)

the sudden and unexpected death of an apparently healthy infant, not explained by careful postmortem studies. It typically occurs between birth and age 9 months, with the highest incidence at 3 to 5 months. Called also crib death or cot death because the infant often is found dead in the crib.



The incidence rate for SIDS in the United States is approximately 10,000 per year. After the first week of life it is the leading cause of death in one-year-olds, and is second only to accidents as a cause of death in children under the age of 15 years. The disorder occurs throughout the world, is more common in families in the lower socioeconomic classes, and affects males slightly more than females and non-Caucasians slightly more than Caucasians.

Children most at risk for SIDS are those who are premature, have a history of apnea from hyaline membrane disease or a seizure disorder, or have a family history of SIDS (especially among siblings) with or without a history of apnea.

There are many misconceptions about the cause of SIDS, most of which are likely to cause feelings of guilt or anger that only add to the heartache of parents whose children have died of the disorder. Among these misconceptions are the beliefs that the infant has suffocated under blankets or from aspirated vomitus, or that contraceptive pills, fluoridation, radioactive fallout, and even lack of breast-feeding have somehow contributed to the disorder.

Identification of infants at risk for SIDS includes determining whether the infant is subject to periods of apnea and if so, why. Diagnostic studies include pneumogram, chest x-ray, determination of chemoreceptor status, metabolic assessment, electrocardiogram, and cardiac and apnea monitoring.

Treatment and prevention of SIDS are necessarily aimed at identifying infants at high risk and instituting a program of apnea monitoring and resuscitation. If home monitoring is deemed necessary, the parents are taught how to place the electrodes over the baby's diaphragm, how to operate the monitoring equipment, and the basic maneuvers for cardiopulmonary resuscitation. While home monitoring does create problems and stress for family members, it usually is not required for more than a few months or at most a year. Most parents feel that the security it provides and the knowledge that their child can survive periods of apnea are worth the sacrifices necessary.

Through the efforts of the National Foundation for Sudden Infant Death, guilt and misunderstandings of the parents about the cause of their infant's death are being handled in a more sensitive and comforting way. Recent interest in research into causes of SIDS has resulted from pressure from parents and members of the national organizations concerned with child health and development. In 1974 Congress passed a bill to set up diagnostic centers throughout the country, and the National Institute of Child Health and Development now allocates more than half a million dollars annually for SIDS research. The address of the National SIDS Alliance is 10500 Little Patuxent Pkwy., Columbia MD 21044.

sud·den in·fant death syn·drome (SIDS),

[MIM*272120]

the sudden death of an apparently healthy infant that remains unexplained after all known possible causes have been ruled out through autopsy, death scene investigation, and review of the medical history.

Synonym(s): cot death, crib death

SIDS is the leading cause of death in infants between 1 week and 1 year of age, with an approximate rate of 2 per 1,000 live births; 6000-7000 babies die of SIDS every year in the U.S. The peak age is 2-4 months and the most deaths occur during the colder months (October to April in the northern hemisphere). The case definition specifically excludes death due to drugs or poisons, apnea, respiratory infection, suffocation, aspiration of vomitus, choking, accidental strangulation, or child abuse. Most victims appear healthy before death, which occurs rapidly, usually during sleep. SIDS strikes families of all races and socioeconomic levels. It is slightly more common in males, and the second child is more susceptible than the first. Some theories suggest a congenital or developmental defect, but the phenomenon does not show familial clustering. Statistical studies have identified certain risk factors, among them maternal smoking before and after birth, inadequate prenatal care, low birth weight, young maternal age, and maternal hard drug use. Some but not all studies have suggested that breast-feeding slightly reduces the risk. Gastric infection with Helicobacter pylori has been speculatively implicated in some cases. The most important risk factor identified to date is sleeping in the prone position. Sleeping on the side is less dangerous than sleeping prone but more dangerous than sleeping supine. The reason for these differences is unknown, but the incidence of SIDS has declined markedly since 1992, when the American Academy of Pediatrics first recommended that healthy infants be placed on their backs for sleep. For infants with gastroesophageal reflux, swallowing dysfunction, or unilateral vocal cord paralysis, the prone position may be preferred. For healthy infants, the supine position does not increase the risk of vomiting and aspiration. Current medical practice emphasizes reduction of risk through avoidance of the prone sleeping position and of maternal smoking, and education, counseling, and emotional support of the parents of victims.

---

sud·den in·fant death syn·drome (SIDS),

[MIM*272120]

the sudden death of an apparently healthy infant that remains unexplained after all known possible causes have been ruled out through autopsy, death scene investigation, and review of the medical history.

Synonym(s): cot death, crib death

SIDS is the leading cause of death in infants between 1 week and 1 year of age, with an approximate rate of 2 per 1,000 live births; 6000-7000 babies die of SIDS every year in the U.S. The peak age is 2-4 months and the most deaths occur during the colder months (October to April in the northern hemisphere). The case definition specifically excludes death due to drugs or poisons, apnea, respiratory infection, suffocation, aspiration of vomitus, choking, accidental strangulation, or child abuse. Most victims appear healthy before death, which occurs rapidly, usually during sleep. SIDS strikes families of all races and socioeconomic levels. It is slightly more common in males, and the second child is more susceptible than the first. Some theories suggest a congenital or developmental defect, but the phenomenon does not show familial clustering. Statistical studies have identified certain risk factors, among them maternal smoking before and after birth, inadequate prenatal care, low birth weight, young maternal age, and maternal hard drug use. Some but not all studies have suggested that breast-feeding slightly reduces the risk. Gastric infection with Helicobacter pylori has been speculatively implicated in some cases. The most important risk factor identified to date is sleeping in the prone position. Sleeping on the side is less dangerous than sleeping prone but more dangerous than sleeping supine. The reason for these differences is unknown, but the incidence of SIDS has declined markedly since 1992, when the American Academy of Pediatrics first recommended that healthy infants be placed on their backs for sleep. For infants with gastroesophageal reflux, swallowing dysfunction, or unilateral vocal cord paralysis, the prone position may be preferred. For healthy infants, the supine position does not increase the risk of vomiting and aspiration. Current medical practice emphasizes reduction of risk through avoidance of the prone sleeping position and of maternal smoking, and education, counseling, and emotional support of the parents of victims.

sudden infant death syndrome

n. Abbr. SIDS

A fatal syndrome that affects sleeping infants under a year old, characterized by a sudden cessation of breathing and thought to be caused by a defect in the central nervous system. Also called crib death.

sudden infant death syndrome

See SIDS.

sud·den in·fant death syn·drome

(SIDS) (sŭd'ĕn in'fănt deth sin'drōm)

Abrupt and inexplicable death of an apparently healthy infant; various theories have been advanced to explain such deaths (e.g., sleep-induced apnea, laryngospasm, overwhelming infectious disease), but none has been generally accepted or demonstrated at autopsy.
Synonym(s): crib death.

sudden infant death syndrome

Cot death. The sudden, unexplained death of an apparently well baby. No apparent cause is established, even after a detailed postmortem examination. Many theories have been put forward and it seems likely that a range of causes is operating, including putting babies down to sleep in the prone position. Many sudden deaths in healthy babies can be explained.

sud·den in·fant death syn·drome

(SIDS) (sŭd'ĕn in'fănt deth sin'drōm) [MIM*272120]

Abrupt and inexplicable death of an apparently healthy infant; various theories have been advanced to explain such deaths (e.g., sleep-induced apnea, laryngospasm, overwhelming infectious disease), but none has been generally accepted or demonstrated at autopsy.
Synonym(s): crib death.