CORTICOSTEROIDS DECREASE EXHALED NITRIC-OXIDE IN CHILDREN WITH ACUTE ASTHMA

Objectives: Nitric oxide (NO) produced in human airways seems to have both homeostatic and proinflammatory actions in the respiratory system . NO production has been shown to be higher in the exhaled air of asth matic adults than in normal subjects. The aim of this study was to eva luate exhaled NO production during asthma exacerbation in children and the effect of a rescue course of oral steroid therapy. Study design: We measured NO in the exhaled air of 16 children (8 girls and 8 boys, aged 6 to 13 years) with an acute asthmatic episode before and after 5 days of therapy with prednisone, and in 16 healthy children. To measu re NO, children inhaled NO-free air and, breathing at tidal volume, ex haled in a circuit from which a chemiluminescence analyzer sampled con tinuously. To assess the effect of acute changes in bronchial caliber on exhaled NO levels, we measured NO before and after a positive bronc hodilation test result with albuterol in seven children with asthma wh ose disease was stable. Results: In the group with acute asthma (force d expiratory volume in 1 second 62% +/- 4.4% predicted, mean +/- SEM), NO levels were significantly higher (31.3 +/- 4.2 parts per billion [ ppb]) than in healthy children (5.4 +/- 0.4 ppb, p < 0.001). Administr ation of prednisone (1 mg/kg per day orally) for 5 days resulted in a mean decrease of 46% +/- 4% in exhaled NO concentrations (16.5 +/- 2.3 ppb, p < 0.001) compared with baseline, accompanied by a significant improvement in lung function (forced expiratory volume in 1 second 90. 7% +/- 4.3% predicted). However, in patients with asthma exhaled NO le vels remained significantly higher than in control children (p < 0.001 ) after steroid treatment. When exhaled NO was measured before and aft er a positive result after bronchodilator reversibility testing, we fo und no difference in exhaled NO levels (24 +/- 3.8 ppb vs 23.8 +/- 3 p pb; difference not significant). This demonstrates that inhaled albute rol and acute changes in bronchial caliber do not affect exhaled NO me asurement. Conclusions: These data show that children with asthma exac erbation have high levels of exhaled NO that rapidly decrease with ora l steroid therapy. We suggest that measurement of exhaled NO may repre sent a noninvasive method of monitoring airway inflammation in childre n with asthma.