title: Assessing direct and indirect airway hyperresponsiveness in children using impulse oscillometry.
abstract: BACKGROUND
  Airway hyperresponsiveness (AHR) is a hallmark of asthma but its assessment is usually restricted to older children who are capable of performing the maneuvers involved in spirometry. In younger children, a feasible option to perform the lung function measurement is impulse oscillometry (IOS), which requires less cooperation.
  
  
  OBJECTIVE
  To evaluate whether assessment of AHR by IOS could differentiate children with various obstructive symptoms from one another.
  
  
  METHODS
  One hundred twenty-one children (median age 6.0 years, range 3.7-8.1 years) were examined: 31 with probable asthma characterized by current troublesome lung symptoms, 61 with a history of early wheezing disorder (recurrent wheezing ≤24 months of age), 15 with a history of bronchopulmonary dysplasia, and 14 healthy controls. Indirect AHR was assessed by exercise and mannitol challenge tests, and direct AHR was assessed with methacholine using IOS. AHR to exercise was defined as an increase of at least 40% in respiratory resistance at 5 Hz. In the mannitol and methacholine challenges, the dose causing an increase of 40% in respiratory resistance at 5 Hz was calculated.
  
  
  RESULTS
  AHR to exercise was good at differentiating children with current troublesome lung symptoms from those in the other groups (P < .001). AHR to methacholine separated children with current troublesome lung symptoms, early wheezing disorder, and bronchopulmonary dysplasia from the controls (P < .001), whereas the mannitol test did not distinguish among the study groups (P = .209).
  
  
  CONCLUSIONS
  The methacholine and exercise challenge tests with IOS identify children with probable asthma characterized by troublesome lung symptoms and therefore may represent a practical aid in the evaluation of AHR in young children.
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland. Electronic address: satu.kalliola@hus.fi.
authors.forename: Satu
authors.initials: S
authors.lastname: Kalliola
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: L Pekka
authors.initials: LP
authors.lastname: Malmberg
authors.affiliation: Children's Hospital, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Kajosaari
authors.affiliation: Department of Otorhinolaryngology, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Petri S
authors.initials: PS
authors.lastname: Mattila
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Pelkonen
authors.affiliation: Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Mika J
authors.initials: MJ
authors.lastname: Mäkelä
mesh_terms: D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis*; D001985:Bronchial Provocation Tests; D001997:Bronchopulmonary Dysplasia / Q000150:complications; D002648:Child; D002675:Child, Preschool; D015444:Exercise; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008353:Mannitol; D016210:Methacholine Chloride; D009991:Oscillometry / Q000379:methods*
chemical_list: D016210:Methacholine Chloride; D008353:Mannitol