Apparent Life-Threatening Event and Sudden Infant Death Syndrome

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11 Apparent Life-Threatening Event and Sudden Infant Death Syndrome

Tara Petersen, Manoj K. Mittal

Apparent Life-Threatening Event

Apparent life-threatening events are frightening events often of sudden onset, affecting predominantly young infants. A National Institutes of Health (NIH) consensus conference in September 1986 defined an apparent life-threatening event (ALTE) as “an episode that is frightening to the observer and that is characterized by some combination of apnea (central or occasionally obstructive), color change (usually cyanotic or pallid but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging. In some cases, the observer fears that the infant has died.”

The community incidence of ALTE has been reported as 2.4 to 9.4 per 1000 live births. It accounts for 0.6% to 1% of emergency department (ED) visits by infants. The median age of infants with ALTE is about 50 days. The incidence is similar in boys and girls.

Etiology and Pathogenesis

The most frequently identified problems associated with an ALTE are digestive (≈50%, most commonly gastroesophageal reflux [GER]), neurologic (30%), respiratory (20%), cardiovascular (5%), metabolic and endocrine (<5%), and diverse other problems (including child abuse). However, up to 50% of cases remain unexplained. The presence of a condition capable of causing ALTE does not equal causation in an individual case. This is particularly true of GER. A study of a cohort of infants with both apnea and GER found that episodes of apnea were seldom associated with GER. However, in instances where they were associated, the predominant sequence of events was obstructive or mixed apnea followed by reflux.

Clinical Presentation

ALTE is a presenting complaint and not a diagnosis. It represents a heterogeneous group of potential underlying disorders. As the NIH definition indicates, it encompasses a broad range of conditions, varying from choking or gagging to obstructive apnea to central apnea.

Because ALTE is a diagnosis based on symptomatology rather than pathophysiology, the differential diagnosis and recommended medical evaluation can be broad. A careful history is often the most helpful part of the evaluation. Determination of whether the infant has been chronically ill or previously well is of utmost importance because a history of previous similar episodes, failure to thrive, poor feeding, and prematurity may provide important clues as to an identifiable cause for the observed symptoms.

A clear description of the event from the caregiver who witnessed the event often contains valuable insight into an underlying cause. Normal infant behaviors such as irregular breathing during REM (rapid eye movement) sleep, periodic breathing, respiratory pauses (5–15 sec), and transient coughing or gagging during feeding may be misinterpreted as abnormal behavior. It is important to carefully use the history and physical examination to distinguish these normal behaviors from underlying pathology.

Infection, gastrointestinal pathology, toxic ingestion, metabolic decompensation, and trauma (both accidental and nonaccidental) are among some of the serious conditions that may initially be identified as an ALTE. Chronic conditions may also present initially as an ALTE (Box 11-1).

Box 11-1

Conditions That May Present Initially as Apparent Life-Threatening Event

• Infections: sepsis, meningitis, encephalitis, urinary tract infection, respiratory tract infections (most notably RSV and pertussis)
• Gastrointestinal: volvulus, intussusception, gastroesophageal reflux, swallowing incoordination
• Toxic exposure: unintentional or intentional ingestion, carbon monoxide poisoning
• Metabolic decompensation: inborn errors of metabolism, endocrinopathies or electrolyte imbalances
• Trauma (accidental or nonaccidental): suffocation, aspiration, inflicted injury
• Cardiac: arrhythmias, cardiomyopathies
• Respiratory: abnormalities of respiratory control, upper airway obstruction, vocal cord dysfunction, laryngotracheomalacia, vascular ring
• Neurologic: central hypoventilation syndrome, seizure or apnea associated with Chiari or other hindbrain malformation
• Genetic: congenital anomalies

RSV, respiratory syncytial virus.

Evaluation and Management

Diagnostic evaluation and the need for laboratory or radiographic studies should be directed by a thorough history and physical examination. The importance of a detailed history and examination was highlighted in a 2005 study that found the diagnosis of ALTE was suggested or made by historical or physical examination findings in approximately 70% of cases.

Both the caretaker who witnessed the episode and any emergency personnel or first responders involved in the case should be interviewed. Key historical elements include:

• State immediately preceding the event: Was the child asleep, awake or crying?
• Position: Was the infant prone, supine, in a car seat, or being held by the caregiver?
• Relationship to feeding: How many hours or minutes had elapsed since the last feeding? Is there any history of emesis, gagging or choking?
• Respiratory effort: Did the infant seem to be struggling to breathe or choking? Was there an increased or decreased respiratory effort? Was there complete cessation of breathing, and if so, for how long?
• Color: Did the child appear cyanotic, pallid, grey, red, or purple?
• Tone: Did the infant appear limp, rigid, or demonstrate tonic or clonic movements?
• Noise: Did the infant cough or have stridor? Was there crying or gasping? Did the infant make any sound at all?
• Eyes: Were the infant’s eyes open or closed? Did they appear to be dazed, staring, rolling, or bulging?
• How long did the event last: Seconds versus minutes? Witnessing an ALTE is frightening to the observer because the infant’s life may be perceived to be in danger. Thus, seconds may seem like minutes. It is often helpful to count out the seconds or minutes to provide a reference point for comparison.
• Did the event require intervention: Did the infant spontaneously return to his or her behavioral baseline? Was gentle or vigorous physical stimulation required? Were rescue breaths given? Did the infant receive cardiopulmonary resuscitation (CPR) by the caregiver or medical personnel?

A careful physical examination should pay particular attention to any abnormalities identified when obtaining the history. Growth parameters, including height, weight, and head circumference should be obtained and compared with age- and gender-appropriate standards. A comprehensive set of vital signs, including body temperature, heart rate, respiratory rate, and pulse oximetry should be obtained. During both the history and physical examination, it is also important to observe the interaction between the caregiver and the infant, as nonaccidental trauma is part of the differential diagnosis.

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