title: A comparison of plethysmography, spirometry and oscillometry for assessing the pulmonary effects of inhaled ipratropium bromide in healthy subjects and patients with asthma.
abstract: OBJECTIVE
  We have compared the ability of plethysmography (sGaw), impulse oscillometry (IOS) and spirometry (FEV(1), MMEF) to detect bronchodilation in response to an anticholinergic.
  
  
  METHODS
  IOS (R5, R20, X5, RF), sGaw and spirometry were measured in 12 healthy subjects and 12 asthmatics. Variability was assessed by performing two measurements, 30 min apart and the effect of increasing the number of readings for each sGaw measurement was also studied. Ipratropium bromide (IB) 10, 20, 100 and 200 microg was administered and the sensitivity of the methods compared by determining the lowest dose that caused changes greater than variability.
  
  
  RESULTS
  In healthy subjects significant changes (P < or = 0.05) occurred at 10 microg for FEV(1) (mean [95% CI]; 1.3%[0.3-2.3]), R5 (mean [95% CI]; -7.9%, [-13.2-2.6]) and R20 (mean [95% CI], -6.4%, [-11.4-1.4]). No significant change was detected when the mean of 3 sGaw readings was used, but with 10 readings significant change was observed at 20 microg; (mean increase [95% CI] 15.2%[8.3-22.1]). In asthmatics significant changes (P < or = 0.05) occurred with IB 10 microg for sGaw (mean [95% CI] 25.6%[11.1-40.1]), R5 (mean [95% CI]-11.3%, [-15.5-7.2]), RF (mean [95% CI] 11.7%[6.1-16.3]), FEV(1) (mean [95% CI] 5.1%[2.6-7.7]) and MMEF (mean [95% CI] 12.3%[2.3-22.2]).
  
  
  CONCLUSIONS
  IOS and spirometry are more sensitive than sGaw in healthy subjects, but the sensitivity of sGaw improved when the number of readings was increased. The most sensitive method for assessing bronchodilation in asthmatics was sGaw.
authors.affiliation: Medicines Evaluation Unit, North-west Lung Research Centre, Wythenshawe Hospital, Manchester, UK. cathhoughton@doctors.org.uk
authors.forename: C M
authors.initials: CM
authors.lastname: Houghton
authors.forename: A A
authors.initials: AA
authors.lastname: Woodcock
authors.forename: D
authors.initials: D
authors.lastname: Singh
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010991:Plethysmography / Q000379:methods; D013147:Spirometry / Q000379:methods
chemical_list: D001993:Bronchodilator Agents; D009241:Ipratropium