Basics
Description
- Sudden infant death syndrome (SIDS) is the sudden and unexpected death of an infant younger than 1 year of age, with onset of the lethal episode apparently occurring during sleep, which remains unexplained after a thorough investigation, including the performance of a complete autopsy, review of the circumstances of death, and review of the clinical history.
- SIDS is a subcategory of deaths described as "sudden unexpected deaths in infancy " (SUDI) or "sudden unexpected infant deaths " (SUID). SUID can include both explained deaths, including suffocation, asphyxia, entrapment, trauma (accidental or nonaccidental), cardiac arrhythmia, infection, and metabolic disorders, and unexplained deaths, including SIDS and those with an undetermined/ill-defined cause of death.
Epidemiology
- Most common cause of death in postneonatal (>1 month old) infants
- Peak age of incidence: 2 " 4 months; uncommon before 2 weeks or after 6 months
- Incidence has been decreasing:
- 1970s: ’ Ό2.5 SIDS deaths per 1,000 live births: SIDS defined somewhat loosely
- 1980s: ’ Ό1.4 per 1,000 live births
- 1990s: ’ Ό1.2 per 1,000 (1992) " 0.7 per 1,000 live births (1999): "Back to Sleep " campaign encouraging supine positioning during sleep in 1994 is associated with steady decline in deaths.
- 2000s: Since 2001, SIDS rate has remained constant ( ’ Ό0.5/1000 live births).
- The rate of SUID (suffocation, asphyxia) or other undetermined or unspecified causes of death has risen.
- For example, the death rate from accidental suffocation and strangulation in bed (ASSB) has more than quadrupled in recent years.
- Largely because of improved death scene investigations, many deaths that previously would have been classified as SIDS are now being classified as having resulted from these other causes of death.
Risk Factors
- Male sex
- Premature birth or low birth weight
- Inadequate prenatal care
- Poverty
- Lower maternal educational level
- Exposure to prenatal, gestational, and postnatal tobacco smoke
- Alcohol and illicit drug use in utero and after infant 's birth
- Maternal substance abuse
- Young maternal age
- Prone and side sleeping position
- Overheating and overbundling
- African American or American Indian/Alaska Native heritage
- Soft sleep surface
- Soft and loose bedding
- Bed sharing, particularly if sharing bed with one or more smokers; if the infant is <11 weeks of age (even if neither parent is a smoker); if sleeping on a surface with soft bedding; if bed sharing adults have consumed alcohol or drugs; if bed sharing with people who are not the infant 's parents; and if the sleep surface is very soft (couches, armchairs, waterbeds)
Potential protective factors include the following:
- Breastfeeding
- Pacifier use at bedtime and naptime
- Regular prenatal care
- Immunizations
- Room sharing without bed sharing
Genetics
- Most likely represents a heterogeneous group of causes of death
- Genetic factors may play a role in some of these deaths. Candidate genes include those encoding ion channel proteins, serotonin transporters, nicotine-metabolizing enzymes and those regulating autonomic nervous system development, inflammation, energy production, hypoglycemia, and thermal regulation.
- There appears to be a complex gene and environment interaction.
- Parents should be reassured that the chance of recurrence in future siblings is small and will be examined during the investigation of the SIDS death.
General Prevention
- Place infants on their backs for every sleep until 1 year of life.
- Use a firm sleep surface.
- Do not use blankets, pillows, bumper pads, sheepskins, or comforters in the infant 's sleep area.
- Avoid tobacco smoke exposure during pregnancy and after birth.
- Room sharing without bed sharing is recommended.
- Breastfeed as much and as long as possible.
- Consider offering a pacifier at naptime and bedtime. If breastfeeding, wait until breastfeeding is well established (3 " 4 weeks) before introducing a pacifier.
- Do not use alcohol or illicit drugs during pregnancy or after birth.
- Avoid overheating.
- Do not cover infant 's head during sleep.
- Immunize your infant.
- Do not use home cardiorespiratory monitors as a strategy to reduce the risk of SIDS.
Pathophysiology
- The "triple risk " model of SIDS describes the interplay of three factors thought to contribute to these deaths: a vulnerable infant, a critical period of development, and stressful environmental challenges.
- Individual traits that influence an infant 's vulnerability to SIDS are characterized as intrinsic risk factors. Examples include serotonin receptor abnormalities noted in the ventral medulla of SIDS infants at autopsy, suggesting derangements in the neural circuits responsible for arousal and cardiorespiratory functioning. Autopsy studies have also revealed changes in the serotonin transporter gene (5-HTT) that ultimately reduce serotonin concentration at these nerve synapses.
- The period from birth to age 6 months is one of rapid brain growth and maturation, as well as motor skill acquisition, such as the ability to lift and turn the head in the event of life-threatening rebreathing or asphyxia.
- Exogenous risk factors such as soft bedding, tobacco smoke, side or prone positioning, and overheating place these vulnerable infants at risk for asphyxia or other physiologic disturbances.
- Failure of arousal in the face of asphyxia or other physiologic disturbances likely contributes to the final pathway leading to these infants ' deaths. Known risk factors for SIDS have been linked to arousal and cardiorespiratory responses. For example:
- Prematurely born infants have immature central respiratory responses.
- When compared with supine-sleeping infants, prone-sleeping infants have increased arousal thresholds.
- Prenatal and postnatal nicotine exposure blunts arousal responses to hypoxia.
Diagnosis
History
- SIDS is a diagnosis of exclusion.
- A thorough postmortem evaluation, including death scene investigation, complete autopsy, and review of the infant 's clinical history, should be done.
- Standardized forms developed by the Centers for Disease Control and Prevention for the collection of the circumstances and factors contributing to these deaths and reporting of cases of SUID are available online at www.cdc.gov/sids/SUIDRFdownload.htm.
- Parents and other caregivers should be interviewed in a sensitive manner so as not to imply that parents or caregivers are blamed for the death. Specifically, the following should be ascertained:
- Signs and symptoms (such as fever, cough, irritability, easy fatigability, and lethargy) that may be suggestive of an acute or chronic medical condition that may have caused or contributed to the death
- Family history of sudden death, condition associated with cardiac arrhythmia, epilepsy, metabolic or genetic disease
- Known risk factors for SIDS and other SUID, including sleep position when placed and found, sleep environment, bed sharing, prematurity, parental smoking history, and history of maternal substance abuse
- Evidence suggestive of accidental suffocation, strangulation, or entrapment
- Evidence suggestive of nonaccidental traumatic injury and other forms of abuse (including medical child abuse, also known as "Munchausen syndrome by proxy " )
Physical Exam
- Normal-appearing infant without obvious reason for death
- May have postmortem lividity and/or a pink, frothy discharge from the mouth or nose
- May have signs of terminal motor activity (clenched fists, trismus, or anal dilation)
- Lack of signs of injury or neglect (malnourishment, dehydration, wasting)
- Care must be taken with the deceased body; only medical examiners and coroners have legal authority to establish the cause of death.
Manipulation or examination of body after the declaration of death may violate applicable laws. All medical paraphernalia used during resuscitation must be left in place.
Diagnostic Tests & Interpretation
Lab
- A full autopsy, including the cranium and cranial contents, must be performed on all infants who die suddenly and unexpectedly.
- A toxicology screen; microbiologic evaluation for bacterial, viral, and fungal infections; and urine and serum chemistries to evaluate for metabolic disease should be performed " whether these are performed at the hospital or by the medical examiner is dictated by local resources and protocols.
Imaging
- Skeletal survey
- Whether this is performed at the hospital or by the medical examiner is dictated by local resources and protocols.
Pathologic Findings
- After a review of a thorough death scene investigation, clinical history, and complete autopsy, pathologists are able to make the diagnosis of SIDS when no other specific cause of death has been identified.
- There are no pathologic findings that are pathognomonic. Approximately 80 " 85% of SIDS infants are noted to have intrathoracic petechiae on examination. Additional common autopsy findings include pulmonary congestion and edema as well as minor airway inflammation.
Differential Diagnosis
- In approximately 10 " 15% of cases of suspected SIDS, an alternate cause of death is identified. These include the following:
- Environmental: asphyxia (due to such causes as overlaying, wedging, choking, obstruction of nose or mouth, rebreathing, neck compression, immersion in water); hyperthermia, hypothermia, toxic exposures
- Infectious: sepsis (bacterial, viral), pneumonia, bronchiolitis, meningitis, myocarditis, pertussis
- Trauma: accidental and nonaccidental trauma (cranial injuries, abdominal trauma, nonaccidental suffocation, and drowning)
- Metabolic: electrolyte disturbances, inborn errors of metabolism, especially involving energy production or toxic metabolites (e.g., medium chain acyl-CoA dehydrogenase deficiency, defects in glycogenolysis, defects in oxidative phosphorylation, urea cycle defects, aminoacidopathies, glycogen storage disease)
- Congenital/anatomic: congenital heart disease, Arnold-Chiari malformation, malrotation, volvulus
- Miscellaneous: adrenal insufficiency, cardiac arrhythmias (channelopathies)
Treatment
Additional Treatment
General Measures
- Prevention rather than treatment is the goal. All caregivers of infants should be educated about SIDS risk reduction strategies, ideally before the infant 's birth.
- For families who have experienced a SIDS death, grief counseling may be helpful.
- Families who are contemplating a subsequent pregnancy should be offered genetic and metabolic screening to rule out any hereditary conditions that may mimic SIDS. Avoidance of risk factors should be stressed. However, this discussion should be done with sensitivity, as discussion of risk factors may incur feelings of guilt, particularly if risk factors were associated with the infant 's death.
Additional Reading
- American Academy of Pediatrics, Committee on Child Abuse and Neglect. Addendum: distinguishing sudden infant death syndrome from child abuse fatalities. Pediatrics. 2001;108(3):812. [View Abstract]
- Hymel KP, Committee on Child Abuse and Neglect, National Association of Medical Examiners. Distinguishing sudden infant death syndrome from child abuse fatalities. Pediatrics. 2006;118(1):421 " 427. [View Abstract]
- Jaafar SH, Jahanfar S, Angolkar M, et al. Effect of restricted pacifier use in breastfeeding term infants for increasing duration of breastfeeding. Cochrane Database Syst Rev. 2012;7:CD007202. doi:10.1002/14651858.CD007202.pub3. [View Abstract]
- Kinney HC, Thach BT. The sudden infant death syndrome. N Engl J Med. 2009;361(8):795 " 805. [View Abstract]
- Moon RY, Fu L. Sudden infant death syndrome: an update. Pediatr Rev. 2012;33(7):314 " 320. [View Abstract]
- Moon RY. SIDS and other sleep-related infant deaths: expansion of recommendations for a safe infant sleeping environment. Pediatrics. 2011;128(5):1030 " 1039. [View Abstract]
- Weese-Mayer DE, Ackerman MJ, Marazita ML, et al. Sudden infant death syndrome: review of implicated genetic factors. Am J Med Genet A. 2007;143A(8):771 " 788. [View Abstract]
- Willinger M, James LS, Catz C. Defining the sudden infant death syndrome (SIDS): deliberations of an expert panel convened by the National Institute of Child Health and Human Development. Pediatr Pathol. 1991;11(5):677 " 684. [View Abstract]
Codes
ICD09
- 798.0 Sudden infant death syndrome
ICD10
- R99 III-defined and unknown cause of mortality
SNOMED
- 51178009 Sudden infant death syndrome (finding)
FAQ
- Q. What is the difference between SIDS and an undetermined cause of death?
- A. SIDS, which is a subcategory of SUID, is most commonly defined as "the sudden death of an infant under 1 year of age, which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and a review of the clinical history " (Willinger et al, 1991). When the cause of death cannot be clearly established (e.g., appears to be SIDS, but death occurred in a sleep environment where accidental suffocation cannot be ruled out), cause of death may be "ill-defined " or "undetermined. "
- Q. Won 't giving a baby a pacifier interfere with breastfeeding?
- A: If a baby is breastfed, there is a theoretical risk of "nipple confusion. " A recent Cochrane Collaboration review on the topic (2012) concluded that "for mothers who are motivated to breastfeed their infants, pacifier use before or after breastfeeding was established did not significantly affect the prevalence or duration of exclusive and partial breastfeeding up to 4 months of age. " However, long-term data beyond 4 months of age are lacking. If concerned, parents can wait until breastfeeding is well established, usually about 3 " 4 weeks, before introducing a pacifier.
- Q: Is it okay for a baby to take a nap while lying prone on the parent 's chest?
- A. No. Parents often fall asleep unintentionally, which can result in a hazardous situation. Falling asleep with the baby while on a couch or sofa is particularly dangerous.