Journal Club

Sudden Unexpected Infant Death (SUID)

• Sudden unexpected infant deaths are defined as deaths in infants less than 1 year of age that occur suddenly and unexpectedly, and whose cause of death are not immediately obvious prior to investigation.

• Each year in the United States, more than 4,500 infants die suddenly of no immediately, obvious cause.

• Sudden unexpected infant deaths (SUID) can be subdivided into:

– 1- explained SUID : includes deaths for which the medical examiner determines that there is a specific cause

– 2- unexplained SUID : includes those deaths considered to be sudden infant death syndrome (SIDS)

• Half of these Sudden Unexpected Infant Deaths (SUID) are due to Sudden Infant Death Syndrome (SIDS).

5 %

1-5%

Sudden Infant Death Syndrome

• The current definition of SIDS, developed in 1991, is the sudden death of an infant younger than one year that remains unexplained after a thorough case investigation, including a complete autopsy, examination of the death scene, and review of the clinical history.

• In the United States, SIDS affects 0.57 per 1,000 live births, totaling more than 2,200 deaths per year.

• In Israel by 2005 SIDS affects 0.36 per 10000 live birth.

• SIDS remains the third leading cause of death in infancy and the most common cause of death between 1 month and 1 year of age.

• SIDS usually occurs between the second and fourth months of life.

• Over 80 percent of SIDS deaths occur between midnight and 6 AM

תמותת תינוקות בישראל

• Because most infant deaths are incompletely investigated, the true incidence of sudden infant death syndrome in Israel is not known.

Sleeping position is the most easily modifiable risk factor

breast-feeding

Room-sharing 

Fan use  0.28(0.10-0.77)

 0.55(0.44-0.69)

“Back to Sleep” campaign

• Patient education efforts that recommended the supine sleeping position in the 1990s resulted in a 50 to 70 percent decrease in SIDS rates.

Pathophysiology

• SIDS is a polygenic, multifactorial condition, with genetic, environmental, and behavioral/sociocultural factors as contributors.

• Failure of arousal mechanisms likely plays an important role in the final pathway to death.

• Significant controversy revolves around the pathophysiology of SIDS.

• Three common autopsy findings include unclotted blood in the heart, intrathoracic petechiae and fluid-filled, heavier organs.

• “Apnea theory” of SIDS was proposed in the 1970s which led to the creation of an apnea monitoring industry.

• Current literature supports a triple-risk model, which suggests that SIDS is the final common pathway of three coinciding factors:– An underlying vulnerability– Stressed by an exogenous source– Occur during a critical developmental period

• Current SIDS research topics include investigation of ion channel abnormalities, autonomic nervous system disturbances, and the effects of nicotine on the developing brain.

• Failure of arousal mechanisms likely plays an important role in the final pathway to death.

• Serotonin receptor abnormalities have been found throughout the ventral medulla in victims of SIDS.

• Polymorphisms occurring at higher incidence in SIDS compared to controls:– 7 cardiac ion channelopathy genes that are proarrhythmic– 3 5-HT genes– 8 autonomic nervous system (ANS) development genes– 6 genes related to infection and inflammation that are pro-

inflammatory– 1 gene related to energy production.

DEFORMATIONAL PLAGIOCEPHALY

• Deformational plagiocephaly is flattening of the occiput, which affects up to one half of infants who sleep in the supine position.

• To decrease the risk of skull deformities, infants should have supervised “tummy time,” meaning that when awake, infants should spend as much time as possible on their stomachs.

• A history of one or more apneic episodes does not increase the risk of SIDS, and the use of home apnea monitors does not lower the risk of SIDS.

• Pacifier use appears to decrease the risk of SIDS, and the 1995 AAP position statement on SIDS prevention suggests offering the infant a pacifier at nap or bedtime.

• Investigation of a potential SIDS death should include a thorough death scene evaluation and a complete autopsy, with a radiographic skeletal survey and toxicology studies.

• A known cause of death is identified by the postmortem examination in approximately 15 percent of suspected

SIDS cases.

• The status of “virtopsy” as a potential alternative to traditional autopsy.

Apparent Life-Threatening Events

• Apparent life-threatening events (ALTEs) are apneic episodes associated with changes in skin color (e.g., cyanosis, pallor, erythema), changes in muscle tone, and choking or gasping.

• ALTEs are relatively common, occurring in approximately one in 400 infants.

•  Recovery occurs only after stimulation or resuscitation.

• Risk factors for ALTEs :– history of apnea, cyanosis, or pallor

– feeding difficulties

– single parenthood

– family history of infant death

– smoking during pregnancy

• An etiology for ALTEs is determined in only one half of cases.

• Over 82 percent of ALTE episodes occur between 8 AM and 8 PM

• Gastrointestinal etiologies (usually gastroesophageal reflux) account for most cases in which a cause is identified.

• Respiratory infections.

• Cardiac disorders, such as valvular disease, arrhythmia, and cardiomyopathy, are responsible for a minority of cases.

• Neurologic causes, such as malignancy, structural abnormalities of the brain, and seizures, are uncommon, but should be considered.

Evaluation

• The history and physical examination are the most important factors in determining an etiology.

• In a case series of 243 patients admitted to a single academic medical center, fewer than 6 percent of all tests ordered were useful in making the diagnosis.

• The only tests found to be of value in detecting causes of ALTEs were: testing for gastroesophageal reflux, urinalysis, neuroimaging, chest radiography, and white blood cell count.

• If the history and physical examination suggest that the event was not life-threatening, or if a probable explanation for the event is identified then no laboratory evaluation may be required.

• In some cases, a limited evaluation is performed to confirm the suspected diagnosis.

• If the detailed description of the event suggests that the child was physiologically compromised, then in-hospital observation with cardiorespiratory monitoring is indicate.

• The initial laboratory evaluation usually includes:

– complete blood count– urinalysis– plasma concentrations of glucose, electrolytes, blood urea

nitrogen (BUN), calcium, magnesium– chest radiograph– electrocardiogram– toxicology screen

Indications for Home Cardiorespiratory (CR) monitoring

• Apnea of prematurity

• Tracheostomy or airway abnormalities

• Neurologic or metabolic disorders affecting respiratory control

• Chronic lung disease

The End