title: Determining the time to maximal bronchodilator response in asthmatic children.
abstract: BACKGROUND
  The interval between bronchodilator administration and post-bronchodilator lung function testing is critical for accurate interpretation of the bronchodilator response. The time course of this response in children is not well documented. We aimed to document the time taken to achieve maximal lung function following salbutamol inhalation.
  
  
  METHODS
  Eighteen asthmatic children between 7 and 18 years of age with a history of bronchodilator responsiveness were recruited. Spirometry was performed before and at 0, 10, 15, 20, 40, 60, and 90 minutes after salbutamol inhalation 600 microg (Ventolin; GlaxoSmithKline) via a spacer (Volumatic; GlaxoSmithKline).
  
  
  RESULTS
  Spirometric indices significantly increased after salbutamol inhalation (p < 0.001). The group median time to maximal response in forced expiratory volume in 1 second (FEV(1)) was 17.5 (10-60: 10th-90th centiles) minutes after salbutamol. The magnitude of group response in FEV(1) was significantly higher at 15 and 20 minutes than at 0 and 10 minutes post-salbutamol inhalation (repeat measures analysis of variance [ANOVA] on ranks; p < 0.05).
  
  
  CONCLUSIONS
  We conclude that a minimal interval of 20 minutes, before re-testing spirometry, is required to document the maximal response to bronchodilators in the majority of asthmatic children.
authors.affiliation: Respiratory Medicine Department, Princess Margaret Hospital for Children, Perth, Australia.
authors.forename: Vaska
authors.initials: V
authors.lastname: Stavreska
authors.forename: Maureen
authors.initials: M
authors.lastname: Verheggen
authors.forename: Jan
authors.initials: J
authors.lastname: Oostryck
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Stick
authors.forename: Graham L
authors.initials: GL
authors.lastname: Hall
mesh_terms: D000293:Adolescent; D000420:Albuterol / Q000008:administration & dosage / Q000494:pharmacology; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000187:drug effects / Q000502:physiology; D012123:Pulmonary Ventilation / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests / Q000379:methods; D013147:Spirometry; D013997:Time Factors; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol