Are respiratory events and/or arousals during each sleep stage different by upper airway collapsibility?

Background: Obstructive sleep apnoea (OSA) syndrome is thought to be induced pathophysiologically by the interactions of upper airway collapsibility, control of breathing and/or arousability. The withdrawal of excitatory noradrenergic and serotonergic inputs to upper airway motor neurons during REM sleep increases the propensity for upper airway (UA) collapse. Aims: To evaluate the features of respiratory events by UA collapsibility estimated during REM sleep. Methods: Types (apnoea or hypopnoea) and duration of respitatory events, the degree of desaturation, occurrence and timing of arousals were determined with the diagnostic polysomnography. The proportion of apnoeas per total events (A ratio) in supine position during REM sleep was considered as UA collapsibility and three groups were categorized; mild(M, 0.7). Results: 78 male OSA patients with more than 15 per hour of AHI and without heart diseases and/or psychiatric disorders (Age 48±10 years, BMI 27.5 ± 5.1 kg/m2, AHI 38.6± 22.9 /h) were studied. There were no significant differences in age and BMI except AHI(M 24.9, Mo 27.2, S 42.6/h, median) among three groups (M 14, Mo 23, S 41 pts). In M group, no differences were seen in A ratio and the proportion of arousals per events between each sleep stage. There was more proportion of arousals per events during REM sleep in S group than other groups ( S 0.636 vs Mo 0.449, M 0.309, p Conclusion: UA collapsibility estimated during REM sleep affects types of respiratory events and the proportion of arousals during sleep stages. Granted by Japanese society for the promotion of science.