title: Improved bronchodilator effect of deep inhalation after allergen avoidance in asthmatic children.
abstract: BACKGROUND
  In healthy adults and children, deep inhalation (DI) is able to reverse induced bronchoconstriction. This ability is impaired in asthma, but the reasons are still to be elucidated.
  
  
  OBJECTIVE
  This study investigated whether the bronchodilator effect of DI during methacholine-induced bronchoconstriction can be improved by allergen avoidance in asthmatic children, and its relationship with airway inflammation.
  
  
  METHODS
  The effect of DI on methacholine-induced bronchoconstriction was studied at the beginning and the end of a 3-month allergen avoidance period at high altitude in 14 allergic asthmatic children who had severe asthma attacks. Changes in airway caliber were inferred from the respiratory resistance (Rrs) measured by a forced oscillation technique. Results were related to the percentage of eosinophils in induced sputum and compared with those obtained in 9 age-matched nonasthmatic children.
  
  
  RESULTS
  In asthmatic subjects, DI had no significant effect on methacholine-induced increase in Rrs before (P=.62) but significantly reversed it after (P <.01) allergen avoidance. However, the ability of DI to reverse a methacholine-induced increase in Rrs tended to remain less in asthmatic than nonasthmatic children even after allergen avoidance (P=.05). In the asthmatic children, the percentage of eosinophils in induced sputum was decreased at the end of the allergen avoidance period (P <.001), without any significant correlation between sputum eosinophils and airway responsiveness to methacholine or effect of DI.
  
  
  CONCLUSIONS
  A short period of allergen avoidance may improve the ability of DI to reverse induced bronchoconstriction in some asthmatic children. This effect is associated, yet not correlated, with a reduction in airway inflammation.
authors.affiliation: Dipartimento di Medicina Interna, Università di Genova, 16132 Genoa, Italy.
authors.forename: Manlio
authors.initials: M
authors.lastname: Milanese
authors.forename: Diego
authors.initials: D
authors.lastname: Peroni
authors.forename: Silvia
authors.initials: S
authors.lastname: Costella
authors.forename: Raffaele
authors.initials: R
authors.lastname: Aralla
authors.forename: Attilio
authors.initials: A
authors.lastname: Loiacono
authors.forename: Claudio
authors.initials: C
authors.lastname: Barp
authors.forename: Attilio
authors.initials: A
authors.lastname: Boner
authors.forename: Vito
authors.initials: V
authors.lastname: Brusasco
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000485:Allergens / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000188:drug therapy*; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage / Q000627:therapeutic use; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D002648:Child; D004391:Dust / Q000276:immunology; D004804:Eosinophils / Q000166:cytology; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage* / Q000627:therapeutic use; D008925:Mites / Q000276:immunology; D013183:Sputum / Q000276:immunology; D016896:Treatment Outcome
chemical_list: D000485:Allergens; D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents; D004391:Dust; D016210:Methacholine Chloride