A pragmatic approach to apparent life-threatening events

The infant who arrives for medical care after an apparent life-threatening event (ALTE) presents the pediatrician with a host of uncertainties. Such infants, usually 2 to 3 months old, often appear well after the ALTE and may not have distinguishing features in their exam or history. Even extensive testing may fail to reveal a cause of the ALTE.

But parents are frightened and want to make sure nothing is wrong with their child. And you want to rule out the rare possibility of an underlying etiology without subjecting the patient and family to unnecessary testing. Although numerous recommendations for ALTE management are available, they have not been tested rigorously, and little consensus has been reached about medical management of this condition.^1,2 As a result, ALTE care across the country is quite variable.³ We offer some commonsense recommendations on tests to perform, when to hospitalize, and how to follow up with the child who has had an ALTE.

A little background

Studies conducted before this formal definition was adopted provided limited information on the epidemiology and causes of ALTEs, because they relied on a nonspecific definition that focused on the events' relationship to SIDS. Although the incidence of ALTEs is still unclear, they are reported to occur in about 0.6 to 9.4/1,000 live-born infants and account for almost 1% of emergency department (ED) visits for children younger than 1 year.^5,6

What causes an ALTE?

An ALTE has many potential causes, such as sepsis, bronchiolitis, or, as is common, no underlying disorder. The pediatrician typically does not witness the event, and the parent's description may be subjective and difficult to interpret. You must determine, for example, whether episodic "skin color change" was acrocyanosis, central cyanosis, plethora, or pallor. And was "cessation of breathing" central apnea, obstructive apnea, or periodic breathing of the newborn?

The differential diagnosis for ALTEs is enormous, but studies have consistently shown that a diagnosis is found in fewer than half of ALTE cases.^2,6 In descending order of prevalence, the most common hospital discharge diagnoses for patients after an ALTE are gastroesophageal reflux, unknown cause , seizures, and jower respiratory-tract infections.⁶

Other rarer diagnoses include nonaccidental trauma, metabolic disease, cardiac arrhythmias, sepsis, pertussis, and medication misdose or overdose.

Although the majority of ALTEs are not associated with a diagnosis, the literature offers some reassurance that most events will not recur or lead to significant morbidity or mortality. And a few studies with long-term follow-up suggest that diagnosis at the time of discharge does not predict adverse outcomes.^7,8 The diagnosis of gastroesophageal reflux, for example, may not be the actual cause of an ALTE but rather an incidental finding, as infants with or without an ALTE have equal rates and severity of reflux.⁹

Infants with an ALTE have been reported to differ from infants without an ALTE in certain ways- for example, in their cardiovascular responses to hypoxia.¹⁰ But adopting these studies' findings for clinical use is questionable because of their small sample sizes, the small differences in responses noted between study groups, the lack of a plausible biologic explanation for the observed differences, and the more recent data demonstrating that the etiology of ALTEs is heterogeneous.^7,8