Effect of body position and sleep state on obstructive sleep apnea severity in children with Down syndrome

To investigate the influence of sleep position and sleep state on obstructive sleep apnea (OSA) severity in in children with Down syndrome (DS). DESIGN: Retrospective review. SETTING: Sleep disorders laboratory of a tertiary medical center. PARTICIPANTS: Children with Down syndrome and typically developing children matched for age, gender, apneahypopnea index (AHI), and year of polysomnogram. MEASUREMENTS AND RESULTS: Sleep variables from baseline polysomnography. Sensor-recorded position (supine, prone, lateral) was expressed as the percentage of total sleep time. The AHI was calculated in each sleep state (NREM, REM), position, and position-sleep state combination. Of 76 DS subjects (55 male) the median age and AHI were 4.6 years (range 0.2-17.8 years) and 7.4 events/h (range 0-133). In all subjects, AHI was higher in REM than NREM (p <0.05); however, the NREM AHI was higher in DS subjects than controls (p <0.05). Compared to controls, the percentage of prone sleep was greater in DS subjects (p <0.05), but the percentage of supine or non-supine (prone plus lateral) sleep was no different. For DS subjects alone, NREM AHI was higher in supine than non-supine sleep (p <0.05). CONCLUSION: In DS and non-DS children alike, respiratory events are predominantly REM related. However, when matched for OSA severity, children with DS have a higher NREM AHI, which is worse in the supine position, perhaps indicating a positional effect compounded by underlying hypotonia inherent to DS. These findings illustrate the clinical importance of NREM respiratory events in the DS population and implications for treatment options.