title: Airway changes in obstructive sleep apnoea patients associated with a supine versus an upright position examined using cone beam computed tomography.
abstract: OBJECTIVE
  This study aimed to describe total volume and cross-sectional area measurement changes in obstructive sleep apnoea patients associated with a supine versus an upright position.
  
  
  METHODS
  A retrospective chart review of patients who underwent cone beam computed tomography in upright and supine positions was performed, and the images were analysed.
  
  
  RESULTS
  Five obstructive sleep apnoea patients (all male) underwent both upright and supine cone beam computed tomography imaging. Mean age was 35.0 ± 9.3 years, mean body mass index was 28.1 ± 2.7 kg/m2 and mean apnoea-hypopnoea index was 39.3 ± 23.0 per hour. The airway was smaller when patients were in a supine compared with an upright position, as reflected by decreases in the following airway measurements: total volume; posterior nasal spine, uvula tip, retrolingual and tongue base (not significant) cross-sectional areas; and site of the minimum cross-sectional area (of the overall airway). Total airway volume decreased by 32.6 per cent and cross-sectional area measurements decreased between 32.3 and 75.9 per cent when patients were in a supine position.
  
  
  CONCLUSIONS
  In this case series, the airway of obstructive sleep apnoea patients was significantly smaller when patients were in a supine compared with an upright position.
authors.affiliation: Department of Sleep Medicine - Stanford Hospitals and Clinics,Redwood City,California,USA.
authors.forename: M
authors.initials: M
authors.lastname: Camacho
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery,Stanford Hospitals and Clinics,Stanford,California,USA.
authors.forename: R
authors.initials: R
authors.lastname: Capasso
authors.affiliation: Department of Plastic Surgery,Stanford Hospitals and Clinics,Stanford,California,USA.
authors.forename: S
authors.initials: S
authors.lastname: Schendel
mesh_terms: D000328:Adult; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D016683:Supine Position; D014132:Trachea / Q000502:physiology