title: The interpretation of exhaled nitric oxide values in children with asthma depends on the degree of bronchoconstriction and the levels of asthma severity.
abstract: BACKGROUND
  The clinical implications of fractional exhaled nitric oxide (F(ENO)) measurements in childhood asthma are unclear. We aimed to evaluate the relationship between the level of exhaled nitric oxide and pre-bronchodilator FEV1 and the change in FEV1 after bronchodilator in children with asthma.
  
  
  METHODS
  This was a retrospective, cross-sectional study. We evaluated data from medical documentation of children with asthma with special attention to F(ENO) results, asthma severity, FEV1 (% predicted), and bronchial reversibility test.
  
  
  RESULTS
  Four hundred and five subjects (age 6-18 y) completed the study. Median levels of F(ENO) increased linearly with subjects' age (P = .03). We found a nonlinear trend of pre-bronchodilator FEV1 across 4 quartiles of F(ENO) in episodic and mild asthma; we observed lower pre-bronchodilator FEV1 in children with higher F(ENO), but only up to the F(ENO) value of 35.4 ppb; in children with F(ENO) value > 35.4 ppb, pre-bronchodilator FEV1 was increased. We found a linear increasing trend of change from baseline (after 400 μg of salbutamol) in FEV1 across F(ENO) categories in children with moderate asthma.
  
  
  CONCLUSIONS
  Our results suggest a need to measure F(ENO) before as well as after spirometry. Consequently, in children with asthma with bronchial obstruction, we suggest assessing F(ENO) after short-acting β2 agonists as well. (ClinicalTrials.gov registration NCT00815984.).
authors.affiliation: Department of Pediatrics and Allergy, Medical University of Lodz, N Copernicus Hospital.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Grzelewski
authors.affiliation: Department of Pediatrics and Allergy, Medical University of Lodz, N Copernicus Hospital.
authors.forename: Paweł
authors.initials: P
authors.lastname: Majak
authors.affiliation: Department of Pediatrics and Allergy, Medical University of Lodz, N Copernicus Hospital.
authors.forename: Joanna
authors.initials: J
authors.lastname: Jerzyńska
authors.affiliation: Department of Social and Preventive Medicine, Medical University of Lodz.
authors.forename: Włodzimierz
authors.initials: W
authors.lastname: Stelmach
authors.affiliation: Institute of Dental Surgery, Faculty of Medicine and Dentistry, Medical University of Lodz.
authors.forename: Rafał
authors.initials: R
authors.lastname: Stelmach
authors.affiliation: Institute of Dental Surgery, Faculty of Medicine and Dentistry, Medical University of Lodz.
authors.forename: Anna
authors.initials: A
authors.lastname: Janas
authors.affiliation: Faculty of Nursing and Midwifery, Division of Nursing, Medical University of Lodz.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Grzelewska
authors.affiliation: Military Teaching Hospital No. 2, Medical University of Lodz.
authors.forename: Konrad
authors.initials: K
authors.lastname: Witkowski
authors.affiliation: Department of Laboratory Diagnostics, Medical University of Lodz, N. Barlicki Hospital, Lodz, Poland.
authors.forename: Eusebio
authors.initials: E
authors.lastname: Makandjou-Ola
authors.affiliation: Department of Pediatrics and Allergy, Medical University of Lodz, N Copernicus Hospital alergol@kopernik.lodz.pl.
authors.forename: Iwona
authors.initials: I
authors.lastname: Stelmach
mesh_terms: D000293:Adolescent; D000420:Albuterol / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D016084:Bronchoconstriction / Q000502:physiology; D001993:Bronchodilator Agents / Q000627:therapeutic use; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D001993:Bronchodilator Agents; D009569:Nitric Oxide; D000420:Albuterol
keywords: FENO; FEV1; airway caliber; asthma; asthma severity; children; glucocorticosteroids