Obstructive sleep apnea syndrome(OSA) can divided into two groups, positional (PP) and non-positional(NPP) obstructive sleep apnea syndrome, according to the body position while sleeping. In this study, we evaluated the differences of anthropometirc data and polysomnographic recordings between the two types of sleep apnea syndrome.

Fifty patients with OSA were divided two groups by Cartwright's criteria. The supine respiratory disturbance index (RDI) was at least two times higher than the lateral RDI in the PP group, and the supine RDI was less than twice the lateral RDI in the NPP group. This patients underwent standardized polysomnographic recordings. The anthropometirc data and polysomnographic data were analyzed, statistically.

Of all 50 patients, 30% were found to be positional OSA. BMI was significantly higher in the PP group(p<0.05). Total sleep time was significantly longer in the PP group (350.6±46.0min, p<0.05). Sleep efficiency was high in the PP group(89.6± 6.4%, 85.6±9.9%, p<0.05). Deep sleep was significantly higher and light sleep was lower in the PP group than in the NPP group but no difference was observed in REM sleep between the two groups. Apnea index(AI) and RDI were significantly lower(17.0±10.6, 28.5±13.3, p<0.05) and mean arterial oxygen saturation was higher in the PP group(92.7 ±1.8%, p<0.05) than in the NPP group.

Body position during sleep has a profound effect on the frequency and severity of breathing abnormalities in OSA patients. A polysomnographic evaluation for suspected OSA patients must include monitoring of the body position. Breathing function in OSA patients can be improved by controlling their obesity and through postural therapy.