title: Airway hyper-responsiveness and small airway function in children with well-controlled asthma.
abstract: BACKGROUND
  Airway hyper-responsiveness (AHR) and small airway function are critical to children with asthma. Little is known about the role of the small airway in well-controlled subjects with AHR. We aimed to evaluate AHR and small airway function in children with well-controlled asthma, and to investigate the association between them.
  
  
  METHODS
  We studied 116 cases of children with well-controlled asthma (group A), 46 cases healthy children as controls (group C). Spirometry, impulse oscillometry (IOS), and methacholine challenge test (MCT) were conducted on all the children.
  
  
  RESULTS
  (i) Group A and group C had no differences in forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) ratio (P > 0.05). Forced expiratory flow between 25 and 75% of vital capacity (FEF25-75) and reactance at 5 Hz (X5) in group A were significantly lower than those in group C. (ii) One hundred and five cases (90.5%) of group A proved positive to MCT. (iii) FEF25-75 in group A proved positive to MCT but were lower than those proved negative (P < 0.05).
  
  
  CONCLUSIONS
  AHR persisted in majority of children with well-controlled asthma. Among children with well-controlled asthma, small airway function was lower in those with AHR than those without AHR.
authors.affiliation: Department of Respiratory, Children's Hospital of FuDan University, ShangHai, China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Respiratory, Children's Hospital of FuDan University, ShangHai, China.
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Respiratory, Children's Hospital of FuDan University, ShangHai, China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Respiratory, Children's Hospital of FuDan University, ShangHai, China.
authors.forename: Libo
authors.initials: L
authors.lastname: Wang
mesh_terms: D001249:Asthma / Q000503:physiopathology*; D058070:Asymptomatic Diseases; D055745:Bronchioles / Q000502:physiology*; D002648:Child; D006801:Humans; D016210:Methacholine Chloride; D009991:Oscillometry; D012130:Respiratory Hypersensitivity / Q000503:physiopathology*; D013147:Spirometry; D014797:Vital Capacity
chemical_list: D016210:Methacholine Chloride