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Canadian Respiratory Journal
Volume 22, Issue 3, Pages 153-156
http://dx.doi.org/10.1155/2015/851063
Original Article

Association among Fraction of Exhaled Nitrous Oxide, Bronchodilator Response and Inhaled Corticosteroid Type

Ryan W Smith,1 Kim Downey,2 Nadia Snow,2 Sharon Dell,3 and W Gary Smith2

1Department of General Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Canada
2Paediatric Asthma Centre, Orillia Soldiers’ Memorial Hospital, Orillia, Toronto, Ontario, Canada
3Division of Respiratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

Copyright © 2015 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

BACKGROUND: Fraction of exhaled nitrous oxide (FeNO) is a known marker of airway inflammation and a topic of recent investigation for asthma control in children.

OBJECTIVE: To investigate the relationship among FeNO and bronchodilator response measured by spirometry and types of inhaled corticosteroids (ICS).

METHODS: A one-year review of children tested with spirometry and FeNO in a regional pediatric asthma centre was conducted.

RESULTS: A total of 183 children were included (mean [± SD] age 12.8±2.8 years). Fluticasone was used most commonly (n=66 [36.1%]), followed by ciclesonide (n=50 [27.3%]). Most children (n=73 [39.9%]) had moderate persistent asthma. Increased FeNO was associated with percent change in forced expiratory volume in 1 s (FEV1) after bronchodilator adjusted for allergic rhinitis, parental smoking and ICS type (B=0.08 [95% CI 0.04 to 0.12]; P<0.001). Similarly, FeNO was associated with percent change in forced expiratory flow at 25% to 75% of the pulmonary volume (FEF25–75) after bronchodilator adjusted for parental smoking and ICS type (B=0.13 [95% CI 0.01 to 0.24]; P=0.03). FeNO accounted for only 16% and 9% of the variability in FEV1 and FEF25–75, respectively. Mean-adjusted FeNO was lowest in fluticasone users compared with no ICS (mean difference 18.6 parts per billion [ppb] [95% CI 1.0 to 36.2]) and there was no difference in adjusted FeNO level between ciclesonide and no ICS (5.9 ppb [95% CI −9.0 to 20.8]).

CONCLUSION: FeNO levels correlated with bronchodilator response in a regional pediatric asthma centre. However, FeNO accounted for only 16% and 9% of the variability in FEV1 and FEF25–75, respectively. Mean adjusted FeNO varied according to ICS type, suggesting a difference in relative efficacy between ICS beyond their dose equivalents.