title: Surface tension of upper airway mucosal lining liquid in obstructive sleep apnea/hypopnea syndrome.
abstract: OBJECTIVE
  The obstructive sleep apnea hypopnea syndrome (OSAHS) is a disorder characterized by repetitive closure and reopening of the upper airway during sleep. Upper airway luminal patency is influenced by the surface tension (gamma) acting within the liquid layer lining the upper airway. The aim of the present study was to examine the gamma of upper airway mucosal lining liquid (UAL) in both healthy subjects and patients with OSAHS before and after sleep.
  
  
  METHODS
  Measurements were performed before (PM) and after (AM) an overnight polysomnographic study.
  
  
  METHODS
  Sleep laboratory.
  
  
  METHODS
  We studied 11 healthy adults (5 men, 6 women) and 15 patients with OSAHS (14 men, 1 woman).
  
  
  METHODS
  None.
  
  
  RESULTS
  The gamma of UAL ("pull-off' force technique, pooled PM and AM samples) in patients with OSAHS was increased (59.9 [53.8, 58.8] mN/m; mean [95% confidence interval]) compared with healthy subjects (56.3 [57.7, 62.1] mN/m; linear mixed effects models; P =.05). In both groups there was no significant difference between PM (56.6 [53.7, 59.5] mN/m for healthy subjects, 60.1 [57.9, 62.3] mN/m for the patients with OSAHS) and AM (56.1 [51.8, 60.4] mN/m and 59.6 [57.4, 61.8] mN/m, respectively) samples for gamma of UAL and salivary flow rate (5 minutes unstimulated collection; PM =0.53 [0.22, 0.84] mL/minute for healthy subjects, 0.38 [0.22, 0.54] mL/minute for OSAHS; AM=0.39 [0.23, 0.55] mL/minute and 0.32 [0.2, 0.44] mL/minute). However, the occurrence of nasal breathing during sleep was associated with a fall in gamma of UAL overnight (r2 = 0.15, P < .05).
  
  
  CONCLUSIONS
  Patients with OSAHS have normal salivary flow rate but an increased gamma of UAL. In both healthy subjects and OSAHS patients, nasal breathing during sleep was associated with an overnight fall in the gamma of UAL.
authors.affiliation: Ludwig Engel Centre for Respiratory Research, Westmead Hospital, Westmead, New South Wales, Australia. jason_kirkness@wmi.usyd.edu.au
authors.forename: Jason P
authors.initials: JP
authors.lastname: Kirkness
authors.forename: Melanie
authors.initials: M
authors.lastname: Madronio
authors.forename: Rosie
authors.initials: R
authors.lastname: Stavrinou
authors.forename: John R
authors.initials: JR
authors.lastname: Wheatley
authors.forename: Terence C
authors.initials: TC
authors.lastname: Amis
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D009297:Nasal Mucosa / Q000502:physiology*; D017286:Polysomnography; D012472:Salivation / Q000502:physiology; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000503:physiopathology; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology; D013500:Surface Tension