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

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 microg budesonide equivalent, range 100-1600 microg) and maintained FENO> or =20 p.p.b., we optimized the inhalation technique by thorough instruction and measured FENO 2 weeks later. Then, if FENO remained > or =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 microg 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 beta2-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.