Evaluation and management of apparent life-threatening events in children

Author: Karen L. Hall, Barry Zalman
Date: June 15, 2005

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)

Evaluation

It is important that physicians who care for children take the history of ALTE seriously and arrange for immediate evaluation. Because these children can be diagnosed with a wide variety of conditions, the workup may be extensive.

The evaluation of the infant with an ALTE begins with a careful history of the event, the circumstances surrounding the event, and any observations made by the caregiver, as well as the resuscitative measures used. (2) The history from the caregiver in this frightening and emotional situation may be unreliable; however, there may be important clues to the underlying precipitating event. Table 3 (2-4) outlines historical information that is helpful in assessing the event.

After the history is obtained, the physical examination must include a general impression of the child, noting any dysmorphic features or obvious malformations. Height, weight, and head circumference measurements should be plotted on appropriate growth charts. A careful neurologic examination, including assessment of muscle tone and physical findings appropriate for the age of the child (e.g., head lag, posturing, motor abilities, eye tracking, social smile), should be performed. Abdominal findings and any sign of trauma or bruising also should be noted. In one study, (6) retinal hemorrhages leading to a diagnosis of child abuse were observed during the dilated ophthalmologic examinations of two children. This finding prompted the investigators to include this examination as standard in the workup at their center.

Laboratory and imaging studies should be performed on the basis of the history and physical examination. (2) Baseline tests for the underlying causes of ALTEs are listed in Table 4. (2-4) Recommendations for a minimum workup are difficult because each case is highly individualized. (2) Because gastrointestinal and infectious causes are common, recommended laboratory studies include complete blood count and appropriate cultures, as well as investigation for gastroesophageal reflux disease (GERD) in children who have a history of gagging, spitting up, vomiting, or coughing, or who have difficulty feeding. (2-4) High-yield tests in patients with an ALTE are complete blood count (infection, anemia), serum bicarbonate and lactate (acidosis), urinalysis (infection), chest radiography (occult respiratory infection), pertussis, and RSV. (4) In one study, (5) investigators reported that lower serum bicarbonate and higher serum lactate levels were predictive of more serious conditions. However, not all laboratory, imaging, or other studies need to be performed in all children. (3)

Once an underlying etiology is identified, further testing is not indicated unless ALTEs continue despite appropriate intervention and treatment of the presumed cause. (2) Important points to remember are dual diagnoses in children and the possibility of child abuse. For example, in a group of infants with other gastrointestinal disorders, GERD also was present. (7) British researchers reported positive pertussis titers in children with RSV. (16) Child abuse also may play a role in children who present with an unexplained ALTE. In a study (17) of children requiring cardiopulmonary resuscitation (CPR), investigators reported that 18 of 77 children in whom a diagnosis was reached had been deliberately suffocated; another seven were victims of Munchausen syndrome by proxy. If a child presents repeatedly with episodes of ALTEs but has negative workup results, Munchausen syndrome by proxy should be considered. This is especially true when the caregiver alone has observed the events. Other historical clues may include a caretaker's personal history of odd medical complaints. Events of children in these situations should resolve when they are monitored in a protected setting or when they are removed from the custody of their primary caregiver.

Management

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KAREN L. HALL, M.D., is director of the Family Medicine Residency program at the University of Florida, Gainesville. She received her medical degree from Eastern Virginia Medical School, Norfolk, served an internship in pediatrics at Letterman Army Medical Center, San Francisco, and completed residency training in family medicine at the University of Florida, Gainesville.

BARRY ZALMAN, D.O., is clinical assistant professor in the Department of Community Health and Family Medicine at the University of Florida, Gainesville. He received his medical degree from the University of Health Sciences College of Osteopathic Medicine, Kansas City, Mo., served an osteopathic internship at Orlando General Hospital, and completed three years of a general surgical residency at Memorial Hospital in York, Pa., and a family medicine residency at the University of Florida, Gainesville.

Address correspondence to Karen L. Hall, M.D., University of Florida, 625 SW Fourth Ave., Gainesville, FL 32601. Reprints are not available from the authors.

The authors indicate that they do not have any conflicts of interest. Sources of funding: none reported.

Members of various family medicine departments develop articles for "Problem-Oriented Diagnosis." This is one in a series from the Department of Community Health and Family Medicine at the University of Florida College of Medicine, Gainesville. Guest coordinator of the series is R. Whit Curry Jr., M.D.

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