To study the response of patients of acute exacerbation of chronic obstructive pulmonary disease with different fractional exhaled nitric oxide (FENO) levels to glucocorticoid.

A total of 105 patients with acute exacerbation of COPD who met the inclusion and exclusion criteria were collected and divided into high FENO group (FENO >25 ppb) and low FENO group (FENO≤25 ppb) according to the FENO level at admission. Routine blood, CRP, blood gas analysis and other related indicators and CAT scores of patients were determined on the first day after admission. All patients were given systemic glucocorticoids for five days, and the rest of the treatment was correspondingly given in combination according to the guideline recommendations. After the treatment of 6 days, blood routine detection of two groups of patients, such as CRP, blood gas result and CAT scores, was recorded again. The changes of CAT score and various indexes before and after the treatment were statistically analyzed. The difference of CAT between the two groups was statistically significant (P<0.001).

There was no significant difference in CAT scores between the two groups on the 6th day of treatment (P>0.05). The CAT scores of high FENO group and low FENO group after treatment were lower than those before treatment, with the difference statistically significant (P<0.001).

The patients with high FENO level before treatment have better response to the overall treatment and better clinical symptom improvement, which indicates that FENO may be a predictor of treatment response in patients with acute exacerbation of COPD.