An apparent life-threatening event (ALTE) is not a specific diagnosis but a description of an acute, unexpected change in an infant's breathing behavior that is frightening to the caretaker and that includes some combination of the following features :
- Apnea — usually no respiratory effort (central) or sometimes effort with difficulty (obstructive)
- Color change — usually cyanotic or pallid but occasionally erythematous or plethoric
- Marked change in muscle tone (usually limpness or rarely rigidity)
- Choking or gagging
In some cases, the observer fears that the infant has died. Recovery occurs only after stimulation or resuscitation. However, episodes are often mislabeled as "ALTEs" even when a parent reports that the child resumed normal breathing after simply being picked up and patted.
After early anecdotal reports of deaths from sudden infant death syndrome (SIDS) in infants with recurrent apnea , enormous amounts of attention, research, and clinical resources were focused on the problem of ALTE in infants. Although various cardiorespiratory, autonomic, and neurophysiologic differences have been demonstrated in ALTE infants as a group, these findings have NOT distinguished individual ALTE infants from normal controls nor provided premortem markers for the risk of SIDS . ALTE infants represent a heterogeneous group of patients of varying ages with diverse pathophysiology. As a result, appropriate evaluation and management should be individualized. (See "Sudden infant death syndrome: Risk factors and risk reduction strategies".)
DEFINITION AND EPIDEMIOLOGY
It is important to recognize that ALTE is not a specific diagnosis; rather, it describes a "chief complaint" that brings an infant to medical attention. The term ALTE was coined by the 1986 National Institutes of Health Consensus Development Conference on Infantile Apnea and Home Monitoring. ALTE replaced misleading terms, such as "near-miss SIDS" or "aborted crib deaths", which implied a direct association between these symptoms and SIDS . A substantial proportion of ALTEs are medically insignificant, since the case definition depends upon the observations of frightened, medically untrained caretakers . The incidence of ALTEs is estimated to be 0.05 to 1 percent in population-based studies [5-8].