Objective:To study the significance of measuring fractional exhaled nitric oxide in patients with asthma-chronic obstructive pulmonary disease overlap syndrome(ACOS).Methods:A total of 88 patients with stable COPD and 30 healthy subjects were recruited into the study.All the patients were divided into chronic obstructive pulmonary disease(COPD)only group(46cases)and ACOS group(42cases).Induced sputum cell counts,serumhign sensitivity C relative protein(hsCRP),serum interleukin 8(IL-8)and tumor necrosis fact...