Differential flow analysis of exhaled nitric oxide in patients with asthma of differing severity

Background The majority of asthmatic patients achieve control of their illness; others do not. It is therefore crucial to validate/develop strategies that help the clinician monitor the disease, improving the response to treatment. Methods We have quantified the inflammation in central and peripheral airways by measuring exhaled nitric oxide (NO) at multiple exhalation flows in 56 asthmatics at different levels of severity (mild, n = 10; moderate stable, n = 17; moderate during exacerbation, n = 11; severe, n = 18, 7 of whom were receiving oral corticosteroids) and 18 healthy control subjects. The reproducibility of the measurement was also assessed. Results Bronchial NO (J no ) in patients with mild asthma (2,363 ± 330 pL/s) [mean ± SD] was higher than in patients with moderate stable asthma (1,300 ± 59 pL/s, p no in patients with mild asthma compared to patients with severe asthma receiving ICS and oral corticosteroids (2,225 ± 246 pL/s). Patients with exacerbations showed a higher J no (3,475 ± 368.9 pL/s, p Conclusions Differential flow analysis of exhaled NO provides additional information about the site of inflammation in asthma and may be useful in assessing the response of peripheral inflammation to therapy.