Abstract:

Objective To investigate the value of detecting fractional exhaled nitric oxide（FeNO）in different parts of the airway in chronic obstructive pulmonary disease（COPD）.Methods A total of 82 COPD patients admitted to our hospital from January 2019 to May 2020 were selected for an observational study. Among them，37 patients with stable COPD and 45 patients with acute exacerbation of COPD were selected，while 20 healthy subjects were selected as the control group. The exhaled nitric oxide（NO）concentration in each group was determined，and the concentration of NO in central airway（FeNO50）and alveolar NO（CaNO）were recorded. Clinical variables such as lung function，white blood cell count（WBC），eosinophil percentage（EOS%），C⁃reactive protein （CRP） and CAT score were collected as the observation indexes.Results CaNO ，CRP and WBC in acute exacerbation of COPD were significantly higher than those in COPD stable group and control group ，and the difference was statistically significant（P < 0.05）. There was a significant positive correlation between CaNO and CAT score（r = 0.627，P < 0.001）and a significant negative correlation between CaNO and FEV1%（r = -0.457， P = 0.002）in COPD with acute exacerbation，while FeNO50 was not significantly correlated with CAT score and FEV1%. Stratified analysis showed that CaNO was significantly increased in CAT score > 20 and FEV1% < 50% groups（P < 0.05），but there was no difference in FeNO50 between the two groups（P > 0.05）. Conclusion The concentration of NO in different parts of the airway was different in COPD patients.CaNO may be a better biological indicator of small airway inflammation in patients with COPD and can be used to monitor inflammatory activity during acute exacerbation of COPD. 

Key words:

fractional exhaled nitric oxide, chronic obstructive pulmonary disease, airway inflamma? tion, alveolar nitric oxide