title: Effect of chronic continuous positive airway pressure (CPAP) therapy on upper airway size in patients with sleep apnoea/hypopnoea syndrome.
abstract: BACKGROUND
  There is evidence to suggest that chronic continuous positive airway pressure (CPAP) therapy may produce reversible changes in upper airway morphology and function in patients with sleep apnoea/hypopnoea. This study was designed to examine the effect of chronic CPAP therapy on upper airway calibre.
  
  
  METHODS
  Twenty four men with the sleep apnoea/hypopnoea syndrome (mean (SE) apnoea/hypopnoea index 37 (5)) underwent lateral cephalometry with measurement of posterior airway space performed before and at least three months after initiation of CPAP therapy.
  
  
  RESULTS
  There was no weight change between the two assessments and mean CPAP use was 4.8 (0.4) hours per night. Posterior airway space (PAS) was measured in erect and supine postures. PAS supine increased with CPAP therapy from a mean (SE) of 11.8 (0.8) mm to 13.4 (0.8) mm, but PAS erect did not. Correlation of the change in PAS (dPAS) before and after CPAP therapy showed an increase with increasing CPAP compliance measured as machine run time both for dPAS supine (r = 0.68) and dPAS erect (r = 0.47).
  
  
  CONCLUSIONS
  Patients with the sleep apnoea/hypopnoea syndrome regularly using CPAP for more than four hours per night all showed an increase in dPAS supine. The use of chronic CPAP increases PAS supine probably by a reduction in upper airway oedema, and the change in size is dependent on CPAP use.
authors.affiliation: Respiratory Medicine Unit, University of Edinburgh, UK.
authors.forename: I L
authors.initials: IL
authors.lastname: Mortimore
authors.forename: P
authors.initials: P
authors.lastname: Kochhar
authors.forename: N J
authors.initials: NJ
authors.lastname: Douglas
mesh_terms: D002508:Cephalometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000473:pathology*; D011175:Positive-Pressure Respiration; D016684:Prone Position; D012891:Sleep Apnea Syndromes / Q000473:pathology / Q000628:therapy*; D016683:Supine Position; D013997:Time Factors