Evaluation and management of apparent life-threatening events in children

American Family Physician,  June 15, 2005  by Karen L. Hall,  Barry Zalman

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Apparent life-threatening event syndrome predominantly affects children younger than one year. This syndrome is characterized by a frightening constellation of symptoms in which the child exhibits some combination of apnea, change in color, change in muscle tone, coughing, or gagging. Approximately 50 percent of these children are diagnosed with an underlying condition that explains the apparent life-threatening event. Commonly, the problems are digestive (up to 50 percent), neurologic (30 percent), respiratory (20 percent), cardiac (5 percent), and endocrine or metabolic (less than 5 percent). Fifty percent of these events are idiopathic, which causes great concern to parents and physicians. The evaluation of an affected infant involves a thorough description of the event as well as prenatal, birth, medical, social, and family history. The physical examination, including careful neurologic examination and notation of any apparent anatomic abnormalities, helps diagnose congenital problems, infection, and conditions contributing to respiratory compromise. The laboratory evaluation is driven by historical and physical findings. Inpatient evaluation and monitoring are recommended in virtually all cases unless investigations are normal. Should the history reflect a severe episode, or should the child require major interventions such as cardiopulmonary resuscitation, inpatient observation and monitoring are recommended, even if physical examination and laboratory findings are normal. Once a presumptive diagnosis is made, events should cease after appropriate intervention. If not, reviewing the history, performing another physical examination, and reassessing the need for laboratory and imaging studies are the next steps. Although consensus statements by the National Institutes of Health and the American Academy of Pediatrics support home monitoring, the relationship of apparent life-threatening event syndrome to sudden infant death syndrome is controversial.

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Many physicians have received a frantic call from an anxious parent stating that his or her child stopped breathing, became limp, or turned blue, but then quickly recovered. In 1986, participants in the National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring defined this event as an "apparent life-threatening event" (ALTE). (1) The underlying impetus for the consensus statement stemmed from questions about the use of home monitoring in preventing morbidity and mortality from apnea-related episodes and sudden infant death syndrome (SIDS). The panel also questioned the relationship of apnea to SIDS. As part of this consensus meeting, the panel defined pathologic apnea, apnea of infancy, apnea of prematurity, ALTE, and SIDS (Table 1). (1) Because review of previous studies failed to establish a clear association between ALTE and SIDS, the panel recommended discarding previously used terms, including "near-miss SIDS" or "aborted crib death." (1,2)

Definition of ALTE

By definition, an ALTE refers to a sudden event, often characterized by apnea or other abrupt changes in the child's behavior (Table 1). (1) Symptoms of an ALTE include one or more of the following: apnea, change in color or muscle tone, coughing, or gagging. (2) These episodes may necessitate stimulation or resuscitation to arouse the child and reinitiate regular breathing.

Incidence

Because demographic data are derived from cases in which children are admitted to hospitals or emergency departments, and because not all children are brought in for evaluation, the true incidence of ALTE syndrome is unknown. The reported incidence is 0.05 to 6 percent. (3,4) Most ALTEs occur in children younger than one year. (4) In one study (5) of 65 patients with an ALTE, the peak incidence occurred between one week and two months of age, with most events occurring in infants younger than 10 weeks.

Premature infants, premature infants with respiratory syncytial virus (RSV) infections, and premature infants who undergo general anesthesia are at increased risk for an ALTE. (4) Children who feed rapidly, cough frequently, or choke during feeding also are at increased risk, and more boys than girls experience ALTEs. (4) One study (5) indicated that infants older than two months who had an ALTE and those with recurrent episodes of ALTEs were more likely to have significant disorders.

Etiology

The underlying etiology of these events varies. An ALTE should be viewed as a manifestation of other conditions rather than a diagnosis in and of itself. Uncovering the cause of the ALTE is important: in one half of patients, an etiology is found, implying that there is a potential for intervention that could eliminate further events. In the remaining patients, a specific diagnosis is never made, placing them in the "idiopathic" category. This may indicate the onset of a serious underlying condition that requires timely evaluation and treatment to reduce the rates of morbidity and mortality (Table 2). (1,2,4-15)