A 2-1/2 month old male infant presents to the emergency department via ambulance in full arrest. The baby has been well until 3 days prior when he developed a mild upper respiratory tract infection. On the day he presents to the ED, his appetite has been somewhat decreased, but there are no other symptoms. His mother left him with the sitter in the morning before going to work. After a feeding, the sitter put him down to sleep. She checked him approximately 30 minutes later, because of the recent URI, and found him apneic, pale, mottled, and limp. She attempted CPR briefly and called 911. CPR and resuscitation standing orders were implemented in transport. The patient arrives intubated with an intraosseous infusion. Two doses of epinephrine have been administered so far.
Birth History: Born at term with a birth weight of 3.3 kg (7 lbs. 4 oz). Uncomplicated perinatal and neonatal course; normal spontaneous vaginal delivery. Discharged from the hospital with his mother on day of life 3.
Exam: VS T 35 degrees C (95 degrees F), pulse and respirations with CPR, BP 100/50 with CPR. The infant is pale, mottled and cyanotic.
Clinical Course: CPR and resuscitation drug protocols are continued; however after 30 minutes of resuscitation, there is no response to these measures and the infant is pronounced dead.
Sudden infant death syndrome (SIDS) is defined as the sudden death of an infant (<1 year of age) that remains unexplained after review of the clinical history, a complete autopsy (including skeletal survey, metabolic and infectious disease assessment, and toxicology investigation), and examination of the death scene. It is a diagnosis of exclusion often affecting previously healthy infants. Despite a recent decline in SIDS deaths, it remains the number one cause of post-neonatal infant mortality with an incidence of 0.7-0.8 per 1000 live births (1). The incidence peaks between 2 and 4 months of age with 90% of SIDS deaths occurring before the age of 6 months. The etiology is unknown, however a number of risk factors have been identified which include: prone sleep position, sleeping on a soft surface, co-sleeping, maternal smoking, overheating, lack of adequate prenatal care, young maternal age, prematurity and/or low birth weight, and male sex. African Americans and American Indians have SIDS rates which are 2-3 times the national average (2).
Many mechanisms have been proposed for SIDS, the most popular of which has been the apnea hypothesis. This theory assumes that infants with documented cardiorespiratory events are at increased risk of SIDS. It was this theory that prompted and has, to some extent, continued to support the long-standing use of home apnea monitors for certain high-risk patient populations such as preterm infants, infants with apparent life threatening events (ALTE), and siblings of SIDS victims. However, a recent study examining cardiorespiratory events in healthy term infants versus those at increased risk for SIDS demonstrated that preterm infants had the largest number of extreme cardiorespiratory events (apnea of at least 30 seconds and bradycardia of <60 bpm for >10 seconds) (3). By 43 weeks postconceptional age, the relative risk of having an extreme event was no longer significant in the preterm versus the full term group. Given the fact that the incidence of SIDS peaks well beyond 43 weeks postconceptional age, it was concluded that prolonged apnea and significant bradycardia were not likely to be immediate precursors to SIDS.
It is currently believed that many mechanisms contribute to SIDS. A leading hypothesis maintains that many of these infants have an immature or abnormal arousal response. Postmortem examinations of the brainstems of infants dying of SIDS have revealed hypoplasia or decreased neurotransmitter binding of the arcuate nucleus. The arcuate nucleus is thought to be involved with the hypercapnic ventilatory response, chemosensitivity, and blood pressure regulation (2). Infants possessing this abnormality may be uniquely prone to central and cardiorespiratory depression resulting from hyperthermia, hypercarbia and hypoxemia during sleep. Death ensues due to failure of the arousal mechanism. This theory supports the notion of placing an infant in the supine (or non-prone) position during sleep, as prone positioning increases the likelihood of the nose and mouth becoming buried in the sleep surface.
Prior 1990, it was recognized that prone sleeping was one of several potential risk factors for SIDS (4). This association was strongly demonstrated in population based, case-control studies conducted in England, New Zealand and Australia. In 1992, the National Institute for Child Health and Human Development convened experts to deliberate on the potential relationship between prone sleeping and SIDS in the United States. Based on their opinion, the American Academy of Pediatrics (AAP) issued a recommendation that healthy newborns be placed on their side or back to sleep. In 1994 the "Back to Sleep" campaign was initiated to inform the public about the risks associated with prone sleeping. In the United States, the frequency of prone sleeping has declined from >70% to approximately 20% with a parallel decrease in the rate of SIDS by >40%. It has been demonstrated that non-prone positioning during sleep is beneficial to preterm/low birth weight infants as well as term infants (5). Current efforts are being made to target African Americans and other infant caregivers (sitters and daycare center personnel) with the "back to sleep" message as the incidence of SIDS still remains relatively high in these populations.
Another modifiable risk factor is the use of soft sleep surfaces and loose bedding (2). Polystyrene bead-filled pillows have been removed from the market. Pillows, quilts, comforters, sheepskins and porous mattresses pose additional risks particularly when placed under the infant. Although maternal smoking has been consistently identified in epidemiologic studies as a major risk factor for SIDS, changing behavior is difficult to accomplish. Bed sharing may pose an additional risk factor; the mechanisms of which include the presence of loose bedding, the possibility of the parent rolling onto the child, entrapment, and rolling of the infant to the prone position. The risk of SIDS associated with co-sleeping is significantly greater among smokers. No specific factors have been identified that are protective against SIDS.
There have been a number of other causes of infant death mistaken for SIDS, the most disturbing of which is infanticide (6). As the occurrence of cases of true SIDS decreases, the proportion of unexplained infant deaths attributable to fatal child abuse may be increasing. It is estimated that infanticide is the cause of 1% to 5% of cases identified as SIDS. In Great Britain, covert video surveillance revealed child abuse in 33 of 39 cases referred for evaluation of recurrent apparent life-threatening events (ALTEs). Intentional suffocation was observed in 30 patients. In addition, 12 out of 41 siblings of these patients had previously died suddenly and unexpectedly. Because autopsy findings cannot distinguish between deliberate asphyxiation and SIDS, certain circumstances should raise concern:
1. Previous recurrent cyanosis, apnea, or ALTE while in the care of the same person.
2. Age of death older than 6 months.
3. Previous unexpected or unexplained deaths of 1 or more siblings.
4. Simultaneous or nearly simultaneous death of twins.
5. Previous death of infants under the care of the same unrelated person.
6. Discovery of blood on the infant's nose or mouth in association with ALTEs.
7. Prolonged QT interval and short and medium chain acyl-CoA dehydrogenase deficiency (disorders of fatty acid oxidation) have also been identified in SIDS victims.
Managing the parents of the SIDS infant poses one of the greatest challenges to the health care provider. Most of these deaths occur at home. Parents are typically in shock, bewildered and very distressed. As in any infant death, guilt is often the prevailing response with the parent questioning what they could or should have done to prevent such a tragedy. Guilt is often compounded by anger and blame. The most appropriate professional response under these circumstances is to demonstrate compassion, empathy and support. It should be recognized that necessary medical questioning is likely to cause additional stress. Parental stress and feelings of guilt or paranoia have been further exacerbated by the professional and public awareness of infanticide as a contributing cause to sudden infant death. A SIDS training manual for emergency responders published by the Prince George's County, Maryland Police Department states the following "Do's" and "Don't's" which are equally relevant to the emergency department or primary care physician (7):
Encourage the parent to be patient with him/herself and not expect too much.
Say you are sorry for what happened .
Allow the parents to express their grief as much as possible.
Reassure them that the child received the best care possible.
Tell the parents that you know how they feel.
Change the subject when the parent mentions their deceased infant.
Avoid mentioning the child's name.
Try to find something positive about the child's death.
Say the parent can always have another child.
Make comments that [previous] medical care may have been inadequate.
Parental anxiety and stress may be further heightened by naive and uninformed, yet well-intentioned family members. It is important to recognize that SIDS has a significant and life-long impact on parents and siblings, possibly leading to chronic emotional illness, divorce, or even suicide.
A recent AAP Policy Statement on SIDS, sleeping environment and sleep position states (2):
1. Infants should be placed for sleep in a nonprone position; supine preferred.
2. A crib that conforms to recognized safety standards is a desirable sleeping environment for infants.
3. Infants should not be put to sleep on waterbeds, sofas, soft mattresses, or other soft surfaces.
4. Avoid soft materials in the infant's sleeping environment.
5. Bed sharing or co-sleeping may be hazardous under certain conditions.
6. Overheating should be avoided.
7. Prone positioning is acceptable when the infant is awake and being observed so that issues related to development and positional plagiocephaly (head asymmetry and deformity) may be addressed.
8. Devices to maintain sleep position or to reduce the risk of rebreathing are not recommended.
9. Home monitors are available to detect cardiorespiratory arrest and may be of value for monitoring selected infants who have extreme cardiorespiratory instability. However, there is no evidence that such monitoring decreases the incidence of SIDS.
10. There is concern that the annual rate of SIDS appears to be leveling off as is the percentage of infants who sleep prone. Thus, the Back to Sleep campaign should continue and be expanded. Avoidance of maternal smoking, overheating, and certain forms of bed sharing should be included as important secondary messages.
In summary, although SIDS remains an enigma, it is reasonable to state that its etiology is multi-factorial and that an abnormal arousal response likely serves as the common denominator. The identification of a number of modifiable risk factors such as sleep position has effectively and dramatically reduced the incidence of SIDS through the application of prevention strategies. Other diagnoses, such as metabolic disorders, prolonged QT syndrome and infanticide account for a percentage of deaths mistaken for SIDS. Due to the unique nature of a SIDS death, sensitivity and compassion for parents and other caregivers is essential while thoroughly investigating the cause(s) of death.
1. True/False. Sudden Infant Death Syndrome has been nearly eradicated due to changes in infant positioning.
2. Which of the following disorders may mimic SIDS:
. . . . . a. galactosemia
. . . . . b. disorders of fatty acid oxidation
. . . . . c. maple syrup urine disease
. . . . . d. hypothyroidism
3. True/False. Co-sleeping is an acceptable practice if a mother is breast-feeding.
4. Infanticide should be considered in dealing with a SIDS death when:
. . . . . a. the parents are adolescents
. . . . . b. the infant is younger than 2 months of age
. . . . . c. previous ALTEs have occurred while under the care of the same person
. . . . . d. intrathoracic petechiae are present on post-mortem
5. True/False. Supine or non-prone positioning is beneficial in reducing the incidence of SIDS in infants born at <32 weeks gestation.
6. An appropriate response to a parent who has lost their child to SIDS is to:
. . . . . a. reassure them that they can always have another child
. . . . . b. use their infant's name often when speaking with them
. . . . . c. tell them you know how they feel
. . . . . d. speak critically about the previous medical management of their infant
7. True/False. Home cardiorespiratory monitors do not prevent SIDS.
1. Toomey S, Bernstein H. Sudden infant death syndrome. Current Opinion in Pediatrics 2001;13:207-210.
2. AAP Task Force on Infant Sleep Position and Sudden Infant Death Syndrome. Changing Concepts of Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position (RE9946). Pediatrics 2000;105(3):650-656.
3. Ramanathan R, et al. Cardiorespiratory Events Recorded on Home Monitors: Comparison of Healthy Infants With Those at Increased Risk for SIDS. JAMA 2001;285:2199-2207.
4. Willinger M, Hoffman HJ, Hartford RB. Infant Sleep Position and Risk for Sudden Infant Death Syndrome: Report of Meeting Held January 13 and 14, 1994, National Institutes of Health, Bethesda, MD. Pediatrics 1994;93(5):814-819.
5. Malloy MH, Freeman DH. Birth Weight- and Gestational Age-Specific Sudden Infant Death Syndrome Mortality: United States, 1991 Versus 1995. Pediatrics 2000;105(6):1227-1231.
6. AAP Committee on Child Abuse and Neglect. Distinguishing Sudden Infant Death Syndrome From Child Abuse Fatalities. Pediatrics 2001;107(2):437-441.
7. Day K. Chapter 14 - Emergency Medical Responders and the Authorities. In: Horchler JN, Morris RR (eds). The SIDS Survival Guide, second edition. 1997, Hyattsville: SIDS Educational Services, Inc., pp 215-216.
Answers to questions
1.False, 2.b, 3.False, 4.c, 5.True, 6.b, 7.True