[Study of the relationship between sleep body posture, sleep phase and severity of obstructive sleep apnea-hypopnea syndrome].

Objective: To study the clinical characteristics and relationship between sleep body posture, sleep phase and occurrence in patients with various degree of obstructive sleep apnea-hypopnea syndrome (OSAHS).

Method: Polysomnography recordings of 100 adults with OSAHS were divided into 3 groups according to AHI: mild with apnea-hypopnea indices (5 < or = AHI < or = 15), moderate (15 < AHI < or = 30) and severe (30 < AHI). The polysomnography data and clinical characteristics were compared between each groups. REM sleep-related OSAHS was defined as REM AHI/NREM AHI > or = 2. Positional OSAHS was defined as supine AHI/non-supine AHI > or = 2.

Result: 90.91% (20/22) patients with mild and 82.35% (14/17) patients with moderate OSAHS were position dependent, 40.91% (9/22) patients with mild and 23.53% (4/17) patients with moderate OSAHS were REM sleep-related OSAHS. The percentage of REM sleep-related OSAHS and position dependent OSAHS were significantly higher in mild and moderate groups compared with in severe group (P < 0.05, respectively). In both mild and moderate groups, the supine AHI was significantly correlated with AHI (r = 0.491, 0.771, P < 0.05, respectively). In severe groups, the non-supine AHI was significantly correlated with AHI and Lowest oxygen saturation (LSaO2) (r = -0.424, 0.527,P < 0.01, respectively), NREM AHI was significantly correlated with LSaO2 (r = 0.470, P < 0.01).

Conclusion: Body position play significant effects in mild and moderate but not severe OSAHS. Patients with severe OSAHS are less likely to spend time in the supine position and REM compared with patients with mild and moderate OSAHS.