title: Flow-volume curve changes in patients with obstructive sleep apnoea and brief upper airway dysfunction.
abstract: OBJECTIVE
  Patients with obstructive sleep apnoea (OSA) and those with brief upper airway dysfunction (BUAD) have been reported to have abnormalities of maximal flow-volume curves. This study was designed to assess the ability of flow-volume curves to predict the presence of OSA or BUAD.
  
  
  METHODS
  Four maximal flow-volume manoeuvres performed by 33 OSA patients and 16 BUAD patients were compared with those of 36 normal subjects. Flow-volume indices, their variability, saw-toothing in the curve and an algorithm based on the flow ratios and shape of the curves were assessed.
  
  
  RESULTS
  When the confounding factors, body mass index (BMI), age, gender and smoking status were taken into account, there was no significant difference in a variety of indices derived from the flow-volume curves between OSA and normal subjects. No BUAD patient had normal flow-volume curves as determined with the algorithm. After BMI, age, gender and smoking status were accounted for, decreased forced expiratory volume in 1 s (FEV1), and increased variability of peak expiratory flow (PEF)/peak inspiratory flow (PIF) and FEV1/PEF remained significantly associated with BUAD.
  
  
  CONCLUSIONS
  These findings suggest that flow-volume curve indices have no value in predicting OSA. Some abnormalities are found in patients with BUAD; a normal flow-volume curve makes the diagnosis of BUAD unlikely.
authors.affiliation: Department of Respiratory Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia.
authors.forename: A H
authors.initials: AH
authors.lastname: Campbell
authors.forename: P A
authors.initials: PA
authors.lastname: Guy
authors.forename: P D
authors.initials: PD
authors.lastname: Rochford
authors.forename: C J
authors.initials: CJ
authors.lastname: Worsnop
authors.forename: R J
authors.initials: RJ
authors.lastname: Pierce
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000402:Airway Obstruction / Q000503:physiopathology*; D015992:Body Mass Index; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007320:Inspiratory Capacity; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D012123:Pulmonary Ventilation; D012737:Sex Factors; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D012907:Smoking; D013147:Spirometry; D014797:Vital Capacity