Changes of Site of Obstruction in Obstructive Sleep Apnea According to Position

Abstract

Objective: To evaluate the changes of site of obstruction in obstructive sleep apnea (OSA) patients according to sleep position.

Method: From December 2010 to December 2011, 113 OSA patients underwent drug-induced sleep endoscopy in the supine and lateral positions. Obstruction site was classified as soft palate (SP), tongue base (TB), lateral wall (LW), larynx (LX), and no obstruction (NO). Patients with a nonsupine RDI above 10 were classified as nonpositioners (NP) and below 10 as positioners (PR).

Results: There were 85 men and 28 women with a mean age of 42.7 years. Mean BMI was 27.1, and mean RDI was 37.5. The PR (position responder) group was 49 patients, which accounts for 43.36% of all enrolled OSA patients (113 patients). Their site of obstruction in supine position was TB (20), SP(13), LW(11), and LX(5). In the lateral position 32 showed no obstruction, 8 showed obstruction at the LW, and the remaining 9 patients showed obstruction at SP. In the NP group (64, 57%), site of obstruction in the supine position was TB (20), SP (11), LW (26), and LX (7). In the lateral position, obstruction was observed at the LW (39), SP (16), TB (5), and LX (4).

Conclusion: Site of obstruction according to sleep position was evaluated for the first time. TB obstruction showed marked improvement when sleep position changed from supine to lateral. Obstruction in the lateral position was mostly due to obstruction at the LW, and position dependency is mostly determined by LW collapsibility.