Respiratory pauses during sleep in near-miss sudden infant death syndrome.

To study transient ventilatory changes in infants with the near-miss sudden infant death syndrome (SIDS), we examined the distribution, frequency, and mean duration of all respiratory pauses defined as expiratory time (Te) greater than 2 s in 12 infants with near-miss SIDS and 10 age-matched normal infants during REM and quiet sleep at 1, 2, 3, and 4 months of age. Using the barometric method, we monitored ventilation and respiratory timing while these infants breathed (1) ambient gas concentrations and (2) 2% CO2. We found that infants with near-miss SIDS did not have more frequent or prolonged respiratory pauses than did normal infants at any age in either REM or quiet sleep breathing ambient gas. With 2% CO2, respiratory pauses decreased in number or were eliminated and their mean duration was shorter in both groups. If these infants have hypoxemia during sleep, these data do not support the hypothesis that hypoxemia is secondary to prolonged and more frequent respiratory pauses.