TY - JOUR T1 - Spontaneous airway obstruction masks FeNO level in patients with asthma but not COPD JF - European Respiratory Journal JO - Eur Respir J VL - 40 IS - Suppl 56 SP - P2208 AU - Haijin Zhao AU - Rui Li AU - Zhengyu Liang AU - Shaoxi Cai Y1 - 2012/09/01 UR - http://erj.ersjournals.com/content/40/Suppl_56/P2208.abstract N2 - Background Airway calibers are related to changes in Fractional exhaled nitric oxide (FeNO) in asthma; however, this effect is not well understood especially during spontaneous airway obstruction.Objective The aim of this study was to evaluate whether FeNO levels could be masked by airway obstruction in patients wit asthma and COPD.Methods FeNO and spirometry measurements were performed before and after albuterol inhalation in 20 steroid-naive asthmatics with moderate to severe airway obstruction. For comparison, 15 normal subjects, 16 asthmatics using inhaled corticosteroids/ long-acting β(2)-adrenoceptor agonist(ICS/LABA combination) and another group of patients with COPD were also studied. All the patients with asthma and COPD recruited had positive bronchodilator test (BDT).Results FeNO(median [25th-75th percentiles]) increased significantly after albuterol inhalation in steroid-naive asthmatics 61.50[40.50-85.00]vs.80.00[53.00-108.00], P=0.000) but not in treated asthmatics 27.50[20.25-35.00] vs 25.00[17.25-38.00], P=0.741), COPD 13.00[9.50-22.00] vs.11.00[6.50-16.00], P=0.017) and normal subjects 11.00[8.00-14.00] vs.11.00[8.00-13.00], P=0.424). The absolute increase in FeNO correlated significantly with the absolute increase in FEV1(r=0.48, P=0.000) in whole asthma patients. There was no significant correlation between FeNO (including pre-and post-bronchodilator) and FEV1 (or FEV1%) in all four groups.Conclusions & Clinical Relevance Spontaneous airway obstruction reduces FeNO level in patients with steroid-naive asthma but not treated asthma and COPD. ER -