Association between Positional Dependency and Obstruction Site in Obstructive Sleep Apnea Syndrome

OBJECTIVES The purpose of this study is to find out associations between positional dependency and obstructive levels based on sleep videofluoroscopy (SVF) in patients with obstructive sleep apnea syndrome (OSAS). METHODS Retrospective review was made of 91 OSAS patients who underwent polysomnography and SVF from August 2009 through June 2010. Polysomnography variables including apnea-hypopnea index (AHI), supine AHI, non-supine AHI, time spent in supine sleep position of the total sleep time and positional dependency (PD) were analyzed. Obstruction sites were evaluated as SVF variables. RESULTS Of 91 patients, 65 (71.4%) were positional patients (PP) and 26 (28.6%) were non-positional patients (NPP). An analysis of polysomnography variables according to PD revealed that overall AHI, non-supine AHI and supine AHI in PP was significantly lower than that in NPP. The patients with soft palate obstruction (SP type) were more likely to have PD than the patients with tongue base obstruction (TB type; P=0.046). PD was inversely related to OSAS severity significantly (P=0.001). CONCLUSION These results provide evidence that positional dependent patients may have higher success rate of soft palate OSA surgery alone than non-positional dependent patients. Although PD may be associated with obstruction site, PD only itself may not be useful in planning surgical treatment for OSAS.