Clinical significance of the increased peak levels of exhaled nitric oxide in patients with bronchial asthma.

Abstract

We measured exhaled nitric oxide (NO) with a chemiluminescence method to elucidate the clinical significance of the increased concentration of exhaled NO in patients with bronchial asthma. Exhaled NO was measured in 25 patients with bronchial asthma and in 10 healthy control subjects. The concentration of exhaled NO in asthmatics was significantly higher than in the controls (250.4 +/- 30.4,59.9 +/- 9.6 ppb, respectively, p < 0.01). Symptomatic patients (unstable asthmatics) had a higher exhaled NO concentration than did the asymptomatic patients (stable asthmatics) (384.2 +/- 32.5,143.6 +/- 18.8 ppb, respectively, p < 0.01). The exhaled NO concentration was significantly correlated with the peak expiratory flow rate (r = 0.671, p < 0.01) and eosinophil ratio in induced sputum (r = 0.772, p < 0.05), but it was not correlated with the parameters of bronchial hyperactivity (Dmin and PD35 Grs). We conclude that the increased concentration of exhaled NO in patients with bronchial asthma reflects the state of airway inflammation, and we suggest that the measurement of exhaled NO is a useful, non-invasive and simple method for the management of bronchial asthma.