title: Less small airway dysfunction in asymptomatic bronchial hyperresponsiveness than in asthma.
abstract: BACKGROUND
  Bronchial hyperresponsiveness (BHR) can be present in subjects without any respiratory symptoms. Little is known about the role of the small airways in asymptomatic subjects with BHR.
  
  
  METHODS
  We investigated small airway function assessed by spirometry and impulse oscillometry, as well as Borg dyspnea scores at baseline and during a methacholine provocation test in 15 subjects with asymptomatic BHR, 15 asthma patients, and 15 healthy controls.
  
  
  RESULTS
  At baseline, small airway function (R5 -R20 and X5 ) was comparable between subjects with asymptomatic BHR and healthy controls, whereas asthma patients showed small airway dysfunction as reflected by higher R5 -R20 and lower X5 values. During methacholine provocation, small airway dysfunction was more severe in asthma patients than in subjects with asymptomatic BHR. Interestingly, a higher increase in small airway dysfunction during methacholine provocation was associated with a higher increase in Borg dyspnea scores in subjects with asymptomatic BHR, but not in asthma patients.
  
  
  CONCLUSIONS
  Subjects with asymptomatic BHR may experience fewer symptoms in daily life because they have less small airway dysfunction.
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Pulmonary Diseases, Groningen, the Netherlands; University of Groningen, University Medical Center Groningen, Groningen Research Institute for Asthma and COPD, Groningen, the Netherlands.
authors.forename: I M
authors.initials: IM
authors.lastname: Boudewijn
authors.forename: E D
authors.initials: ED
authors.lastname: Telenga
authors.forename: E
authors.initials: E
authors.lastname: van der Wiel
authors.forename: T
authors.initials: T
authors.lastname: van der Molen
authors.forename: L
authors.initials: L
authors.lastname: Schiphof
authors.forename: N H T
authors.initials: NH
authors.lastname: Ten Hacken
authors.forename: D S
authors.initials: DS
authors.lastname: Postma
authors.forename: M
authors.initials: M
authors.lastname: van den Berge
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000276:immunology* / Q000503:physiopathology*; D058070:Asymptomatic Diseases / Q000453:epidemiology; D015992:Body Mass Index; D016535:Bronchial Hyperreactivity / Q000453:epidemiology / Q000276:immunology* / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic / Q000639:trends; D055815:Young Adult
chemical_list: D016210:Methacholine Chloride
keywords: asthma; asymptomatic bronchial hyperresponsiveness; small airways