UPPER AIRWAY-RESISTANCE IN INFANTS AT RISK FOR SUDDEN-INFANT-DEATH-SYNDROME

To investigate the relationship between sudden infant death syndrome a nd upper-airway-obstruction, we studied 14 term infants at a mean age of 11 weeks who hod been identified as being at risk for sudden infant death syndrome on the basis of clinical and family histories and poly graphic monitoring. Respiratory efforts during sleep were investigated by esophageal pressure monitoring (all 14 infants) and by monitoring of flow with a pneumotachometer (6 infants). During apparently normol sleep, increased respiratory efforts were shown by intermittent increa ses in the magnitude of the negativity of esophageal pressure. Mild ch anges in tidal volume occurred occasionally, always at the lowest moni tored esophageal pressure of a breath sequence. These tidal volume dec reases had no impact on oxygen saturation but led to o short arousal a nd decreased respiratory efforts, followed by a return to normal breat hing. Occasionally the abnormal increase in upper airway resistance di d not lead to an immediate arousal but instead to a short obstructive apnea that was then followed by an arousal. This investigation indicat es the importance of arousal mechanisms in maintaining normal breathin g during sleep. Any disruption of the arousal mechanisms during sleep (including sleep fragmentation caused by repetitive arousals) may plac e these infants with increased upper airway resistance at risk for obs tructive apnea during sleep.