Clinical significance of small airway function and fractional exhaled nitric oxide measurement in patients with clinically controlled asthma

Objective To investigate the significance of small airway function and fractional exhaled nitric oxide concentration in patients with clinically controlled asthma. Methods 38 patients with clinically controlled asthma were selected in the study. Lung function was performed and the concentrations of fractional exhaled nitric oxide were measured. 22 patients with asthma who were newly diagnosed and 20 healthy subjects were selected as the controls. Results In the 38 patients with clinically controlled asthma,there were 22 cases(57. 9%) of abnormal small airway function. The level of fractional exhaled nitric oxide was 30. 42 ± 25. 35 ppb in patients with clinically controlled asthma,which was lower than that in patients with asthma who were newly diagnosed( 80. 28 ± 45. 62 ppb),( P 0. 01),but significantly higher than that in the healthy controls(16. 15 ± 11. 23 ppb)( P 0. 01). The level of fractional exhaled nitric oxide was obviously higher in patients with clinically controlled asthma than in the controls( P 0. 01). Conclusion Abnormal small airway function and airway inflammation persistently exist in patients with clinically controlled asthma,and the detection of small airway function and fractional exhaled nitric oxide may provide guidances for the treatment of asthma.