The nocturnal-polysomnogram and "non-hypoxic sleep-disordered-breathing" in children.

OBJECTIVE: To characterize sleep-disordered breathing patterns not related to hypoxia resulting in fragmented sleep in children.

METHODS: We reviewed the polysomnogram (PSG) data of children with sleep complaints who were being evaluated for sleep-disordered breathing and had an apnea-hypopnea-index ≤ 3. These data were compared to the recordings of the same children with nasal CPAP administered for one night and to 60 control subjects (children without any sleep complaints). A subgroup of children was monitored with esophageal manometry, but nasal cannula flow data was recorded in all cases.

RESULTS: Abnormal breathing patterns, particularly flow limitation, could be seen with more severity and frequency compared to apnea or hypopnea. The observed abnormal breathing patterns were associated with EEG disturbances.

CONCLUSIONS: Patterns such as flow-limitation, mouth-breathing, changes in inspiratory and expiratory time, rib-cage and expiratory muscle activity, transcutaneous CO2 electrode changes and snoring noises are all variables that should be systematically reviewed when analyzing nocturnal PSG. Current scoring guidelines emphasizes apnea-hypopnea and hypoxic-sleep disordered breathing and therefore treatment is often much delayed in this population of children with evidence of abnormal breathing patterns. Analysis of the various patterns of abnormal breathing noted above allows recognition of "non-hypoxic" sleep-disordered-breathing (SDB).