title: Bronchial allergen challenge in allergic children: continuous increase of nitric oxide in exhaled air 72 hours after allergen inhalation independent of bronchial obstruction.
abstract: BACKGROUND
  Changes in fractional exhaled nitric oxide (FeNO) occurring after bronchial allergen challenges (BAC) are still not understood, neither are any possible associations between FeNO and forced expiratory volume in 1 sec (FEV(1)). The aim of the study was to compare the fluctuations of FeNO and FEV(1), which occur within 72 h of BAC in children sensitive to grass pollen.
  
  
  METHODS
  Seventy-four children were divided into two groups based on their medical histories and the results of skin prick tests with 10 common allergens. Individuals in whom the test yielded a positive result to at least grass pollen (Group A, n = 57), and those with negative test results against all of the allergens applied (Group B, n = 17) were subjected to BAC. FeNO was measured at a baseline and at 1, 8, 21, and 72 h after the last dose of the allergen inhalation, whereas FEV(1) was measured at a baseline, hourly for 8 h after the challenge and at 21 and 72 h thereafter.
  
  
  RESULTS
  Baseline FeNO in sensitive subjects (Group A) was significantly higher than in controls of Group B. In all grass pollen-sensitive subjects, even those that were free of a bronchial response, FeNO was markedly elevated compared to its baseline values, starting from the eighth hour onward, and still increased 72 h post-BAC, whereas FEV(1) returned to a baseline at the 72nd h post-BAC. The highest increase in FeNO was registered in individuals with a dual asthmatic response.
  
  
  CONCLUSIONS
  An increase in FeNO in sensitive subjects starts a few hours later than the decrease in FEV(1). Consequently, measurements of FeNO seem to be useful in long-term monitoring of the allergic reaction triggered by a specific allergen.
authors.affiliation: University Children Hospital, Pediatrics, Gastroenterology and Allergology Department, Medical University of Bialystok, ul. J. Waszyngtona 17, Bialystok, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Swiebocka
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Siergiejko
authors.forename: Zenon
authors.initials: Z
authors.lastname: Siergiejko
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000276:immunology*; D001985:Bronchial Provocation Tests / Q000379:methods*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D011058:Pollen / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D000485:Allergens; D009569:Nitric Oxide