title: Effect of weight loss on upper airway size and facial fat in men with obstructive sleep apnoea.
abstract: BACKGROUND
  Obstructive sleep apnoea (OSA) is commonly associated with obesity and can be improved by weight loss. Changes in upper airway size related to regional fat loss may mediate the improvement in OSA. This study aimed to assess changes in upper airway size and regional facial and abdominal fat with weight loss and their association with OSA improvement.
  
  
  METHODS
  Middle-aged obese men with moderate-to-severe OSA underwent a 24-week sibutramine-assisted weight loss trial. Polysomnography and CT of the head and neck were performed at baseline and 24 weeks. The upper airway lumen and facial and parapharyngeal fat were measured with image analysis software.
  
  
  RESULTS
  Post-intervention there was a significant reduction in weight (-7.8±4.2 kg, p<0.001) and apnoea-hypopnoea index (AHI) (-15.9±20.5 events/h, p<0.001). Velopharyngeal airway volume significantly increased from baseline (5.3±0.4 to 6.3±0.3 cm(3), p<0.01) and facial and paraphayngeal fat volume significantly reduced. A reduction in upper airway length was associated with improvement in AHI (r=0.385, p=0.005). The variance in AHI improvement was best explained by changes in upper airway length and visceral abdominal fat (R(2)=0.31, p=0.004).
  
  
  CONCLUSIONS
  Weight loss increases velopharyngeal airway volume, but changes in upper airway length appear to have a greater influence on the reduction in apnoea frequency. Inter-individual variability in the effects of weight loss on OSA severity cannot be explained in terms of changes in upper airway structure and local fat deposition alone.
authors.affiliation: NHMRC Centre for Sleep Health (CIRUS), Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Sutherland
authors.forename: Richard W W
authors.initials: RW
authors.lastname: Lee
authors.forename: Craig L
authors.initials: CL
authors.lastname: Phillips
authors.forename: George
authors.initials: G
authors.lastname: Dungan
authors.forename: Brendon J
authors.initials: BJ
authors.lastname: Yee
authors.forename: John S
authors.initials: JS
authors.lastname: Magnussen
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Grunstein
authors.forename: Peter A
authors.initials: PA
authors.lastname: Cistulli
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D000368:Aged; D018450:Disease Progression; D005145:Face; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007830:Larynx / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D017286:Polysomnography; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology / Q000534:rehabilitation*; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology* / Q000534:rehabilitation; D014057:Tomography, X-Ray Computed; D015431:Weight Loss / Q000502:physiology*