title: Assessment of bronchodilator responsiveness following methacholine-induced bronchoconstriction in children with asthma.
abstract: OBJECTIVE
  The aim of this study was to investigate bronchodilator responsiveness (BDR) following methacholine-induced bronchoconstriction and to determine differences in BDR according to clinical parameters in children with asthma.
  
  
  METHODS
  The methacholine challenge test was performed in 145 children with mild to moderate asthma, and the provocative concentration causing a 20% decline in FEV1 (PC20) was determined. Immediately after the challenge test, patients were asked to inhale short-acting β2-agonists (SABAs) to achieve BDR, which was assessed as the change in FEV1% predicted×100/post-methacholine FEV1% predicted. For each subject, the asthma medication, blood eosinophil count, serum total IgE, serum eosinophil cationic protein level, and skin prick test result were assessed.
  
  
  RESULTS
  The FEV1 (mean±SD) values of the 145 patients were 90.5±10.9% predicted, 64.2±11.5% predicted, and 86.2±11.2% predicted before and after methacholine inhalation, and following the administration of a SABA, respectively. The BDR did not differ significantly according to asthma medication, age, or gender. However, BDR in the atopy group (37.4±17.7%) was significantly higher than that in the non-atopy group (30.5±10.7%; P=0.037). Patients with blood eosinophilia (38.6±18.1%) displayed increased BDR compared with patients without eosinophilia (32.0±13.8%; P=0.037).
  
  
  CONCLUSIONS
  In children with mild to moderate asthma, the responsiveness to short-acting bronchodilators after methacholine-induced bronchoconstriction was not related to asthma medication, but was higher in children with atopy and/or peripheral blood eosinophilia.
authors.affiliation: Department of Pediatrics, College of Medicine, Korea University, Seoul, Korea.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Bauer
authors.forename: Ha Neul
authors.initials: HN
authors.lastname: Park
authors.forename: Hyeon Seok
authors.initials: HS
authors.lastname: Seo
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Dae Jin
authors.initials: DJ
authors.lastname: Song
authors.forename: Sang Hee
authors.initials: SH
authors.lastname: Park
authors.forename: Ji Tae
authors.initials: JT
authors.lastname: Choung
authors.forename: Young
authors.initials: Y
authors.lastname: Yoo
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Kim