THE ASSOCIATION OF SUDDEN UNEXPECTED INFANT DEATH WITH OBSTRUCTIVE SLEEP-APNEA

We studied the relationship of sudden unexpected infant death/apparent life-threatening events (ALTE) to obstructive sleep apnea (OSA) in 74 index probands who had either sleep-laboratory-confirmed OSA or a cli nical diagnosis of OSA requiring treatment, 62 matched control proband s, and their spouses and first- and second-degree relatives. Sleep was monitored in the home overnight, and OSA was defined by respiratory d isturbance indices (number of apneas/hypopneas per hour of sleep) corr ected for normal increases with age. Information on sudden unexpected infant death/ALTE was obtained by questionnaire and was corroborated. For living relatives, data were obtained by questionnaire, examination , or study (cephalometric radiographs, ventilatory responsiveness to h ypercapnia and hypoxia). Eight index families had 10 infants with sudd en unexpected infant death/ALTE; two control families had three infant s with sudden death (p = 0.11). All told, 91 of the 136 families (inde x plus control) included members with OSA, and all 10 infant death/ALT E families were among these (versus zero of 45 families with no OSA; p = 0.03). The sudden infant death/ALTE families had a greater frequenc y of two or more members with OSA (p = 0.06), reported more respirator y disease or allergy, were more frequently brachycephalic (p = 0.05), and had a smaller mean posterior nasal spine-basion distance (p = 0.00 01) and ratio of anterior mandibular/anterior maxillary dental height (p < 0.05). Ventilatory responses to hypoxia were reduced in members o f families with OSA (p = 0.008), with a trend toward the greatest blun ting in subjects from families with OSA plus sudden unexpected infant death/ALTE. Thus, OSA in adults and sudden unexpected infant death/ALT E in their biologic relatives appear to be related. Familial factors i nfluencing this association may include the degree of the predilection for OSA, liability for respiratory illness or allergy, dimensions of the oral-pharyngeal airway, and ventilatory response to hypoxia.