Inhaled fluticasone decreases bronchial but not alveolar nitric oxide output in asthma

Exhaled nitric oxide (NO) concentration is a noninvasive measure of airway inflammation and is increased in asthma. Inhaled glucocorticoids decrease e xhaled NO concentration, but the relative contributions of alveolar and bro nchial levels to the decrease in exhaled NO concentration are unknown. Alveolar NO concentration and bronchial NO flux can be separately approxima ted by measuring exhaled NO at several exhalation flow rates. The effect of steroid treatment on alveolar and bronchial NO output in asthma was studie d. Alveolar NO concentration and bronchial NO flux were assessed in 16 pati ents with asthma before and during treatment with inhaled fluticasone for 8 weeks and in 16 healthy controls. Before the treatment, asthmatics had increased bronchial NO flux (mean +/- SEM: 3.6 +/-0.4 versus 0.7 +/-0.1 nL.s(-1), p<0.001) but normal alveolar NO concentration (1.2<plus/minus>0.5 versus 1.0 +/-0.2 parts per billion (ppb ), p>0.05) compared with controls Inhaled fluticasone decreased bronchial N O flux from 3.6 +/-0.4 to 0.7 +/-0.1 nL.s(-1)(p<0.01) but had no effect on alveolar NO concentration (before: 1.2<plus/minus>0.5; after: 1.2 +/-0.1 pp b, p>0.05). The forced expiratory volume in one second improved, whereas as thma symptom score and serum levels of eosinophil cationic protein and eosi nophil protein X decreased during the treatment. In conclusion, inhaled fluticasone decreases bronchial but not alveolar nit ric oxide output simultaneously with clinical improvement in patients with asthma.