Apparent life-threatening events (ALTEs) are common and frequently challenging diagnostic dilemmas. Although most evaluations of these patients usually take place in a hospital, primary care physicians will be frequently asked to contribute to various stages of the management of these cases, from initial evaluation of the patient to decisions about long-term monitoring.[1]

The appropriate management of children with an ALTE requires an understanding of commonly accepted definitions, the various potential causes, and the most appropriate management strategies of these conditions. Definitions of an ALTE and other related breathing patterns were clarified in a 1986 National Institutes of Health Consensus document.[2] An ALTE has been defined as “an episode that is frightening to the observer and that is characterized by some combination of apnea, color change, marked change in muscle tone, choking, or gagging” in which, “in some cases, the observer fears that the infant has died.”[2] This definition replaced aborted crib death or near-miss sudden infant death syndrome (SIDS), which misleadingly implied an association between ALTE and SIDS.[2] Other important definitions of concepts related to ALTE are listed in Table 237-1. Most notably, pathological apnea is defined as “a respiratory pause that is prolonged, lasting 20 seconds or longer, or is associated with cyanosis, pallor, hypotonia or bradycardia.”[2] In contrast, periodic breathing, which is commonly noted in young infants, is “a breathing pattern in which there are 3 or more respiratory pauses of greater than 3 seconds' duration with less than 20 seconds of respiration between pauses.”[2]