title: Measuring bronchodilation in COPD clinical trials.
abstract: OBJECTIVE
  The aim of this study was to compare the variability and sensitivity of impulse oscillometry (R5, X5 and RF), plethysmography (Raw and sGaw) and spirometry (FEV1, FVC and MMEF) in order to determine the most powerful technique for assessing bronchodilation in COPD clinical trials.
  
  
  METHODS
  Twenty-four patients with COPD had impulse oscillometry, plethysmography and spirometry measured twice 30 mins apart, to determine variability. Then ascending doses of salbutamol (20, 50, 100, 200, 400 and 800 microg) were given and the same measurements made after each dose. Significant changes greater than variability were determined for each performed measurement (expressed as mean percentage improvement with 95% CI).
  
  
  RESULTS
  Significant effects (P < 0.05) were detected after 20 microg by X5 (18.5% CI 9.8-27.2) RF (11.1% CI 7.2-15.0) and sGaw (21.5% CI 10.1-32.9), and after 50 microg by R5 (16.7% CI 10.8-22.5) and Raw (19.7% CI 13.0-26.4). FEV1 was less sensitive, detecting significant bronchodilation at 100 microg (10.2% CI 7.4-12.9).
  
  
  CONCLUSIONS
  We conclude that impulse oscillometry and plethysmography should be considered the preferred techniques for measuring bronchodilation in COPD clinical trials.
authors.affiliation: Medicines Evaluation Unit, North-west Lung Centre, Wythenshawe Hospital, Manchester, UK. zborrill@meu.org.uk
authors.forename: Z L
authors.initials: ZL
authors.lastname: Borrill
authors.forename: C M
authors.initials: CM
authors.lastname: Houghton
authors.forename: A A
authors.initials: AA
authors.lastname: Woodcock
authors.forename: J
authors.initials: J
authors.lastname: Vestbo
authors.forename: D
authors.initials: D
authors.lastname: Singh
mesh_terms: D000420:Albuterol / Q000008:administration & dosage; D001980:Bronchi / Q000502:physiology*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D002986:Clinical Trials as Topic / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods; D010991:Plethysmography / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D013147:Spirometry / Q000379:methods
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol