title: Association between Positional Dependency and Obstruction Site in Obstructive Sleep Apnea Syndrome.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Otorhinolaryngology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Woong Sang
authors.initials: WS
authors.lastname: Sunwoo
authors.forename: Sung-Lyong
authors.initials: SL
authors.lastname: Hong
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Sung Joon
authors.initials: SJ
authors.lastname: Park
authors.forename: Doo Hee
authors.initials: DH
authors.lastname: Han
authors.forename: Jeong-Whun
authors.initials: JW
authors.lastname: Kim
authors.forename: Chul Hee
authors.initials: CH
authors.lastname: Lee
authors.forename: Chae-Seo
authors.initials: CS
authors.lastname: Rhee