High fractional concentration of nitric oxide in exhaled air despite steroid treatment in asthmatic children

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Abstract
Background The fractional concentration of nitric oxide in exhaled air (FENO) is elevated in atopic asthma and typically responds to treatment with inhaled corticosteroids (ICS). However, some patients have persistently high FENO levels despite treatment. Objective We studied how optimizing the inhalation technique and increasing ICS doses would affect FENO in stable atopic asthmatic children who had elevated FENO while using ICS. Methods In 41 stable asthmatic children who were treated with ICS (median daily dose 800 μg budesonide equivalent, range 100–1600 μg) and maintained FENO20 p.p.b., we optimized the inhalation technique by thorough instruction and measured FENO 2 weeks later. Then, if FENO remained 20 p.p.b., we increased the ICS dose and reassessed FENO 2 weeks later. Results Improving the inhalation technique did not reduce FENO. Increasing ICS from a daily median dose of 800 to 1200 μg budesonide had no significant effect on FENO. FENO correlated positively with symptom scores in the following 2 and 4 weeks (P=0.001, 0.002) and β2‐agonist use the 2 and 4 weeks following FENO measurement (P=0.02, 0.004). Conclusion We conclude that common steps in asthma treatment, i.e. inhalation instruction and increasing ICS dose, were both ineffective in reducing FENO in atopic asthmatic children with elevated FENO values despite treatment with ICS. This implies that FENO cannot simply be incorporated in current treatment guidelines.

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