Objective:To investigate the factors affecting the application of systemic glucocorticoids in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with carbon dioxide (CO 2) retention, and to guide the formulation of a strategy to reduce systemic glucocorticoid exposure. Methods:The AECOPD patients with CO 2 retention admitted to the Ningde Municipal Hospital of Fujian Medical University from January 2017 to December 2019 were enrolled. The general information, past history, times of acute exacerbations within 1 year, pneumonia on admission, causes of COPD, heart failure, blood gas analysis, eosinophil count (EOS), albumin (Alb) and apolipoprotein E (ApoE) levels, exhaled nitric oxide (FeNO) level, inhaled glucocorticoid and non-invasive mechanical ventilation treatment at acute exacerbation were collected. The patients were divided into recommended dosage group (exposure levels in the recommended dosage range, cumulative prednisone dosage ≤ 200 mg) and exceeded group (exposure levels exceeded the recommended dose, cumulative prednisone dosage > 200 mg) according to cumulative systemic glucocorticoid exposure dosage of the patients during hospitalization. The clinical data of patients between the two groups were compared, and possible factors with P < 0.1 in univariate analysis were included in multivariate Logistic regression analysis to screen the related factors of systemic glucocorticoid exposure level in AECOPD patients with CO 2 retention. Results:According to the order of hospitalization, 151 AECOPD patients with CO 2 retention were enrolled, 8 patients were excluded, and 143 patients were enrolled in the analysis. Of the 143 patients, 68 received the recommended dose of systemic glucocorticoid, and 75 received excessive systemic glucocorticoid. Age, percentage of forced expiratory volume in 1 second (FEV1%) at stable phase, frequency of acute exacerbation within 1 year, heart failure ratio, oxygen index (PaO 2/FiO 2), arterial partial pressure of carbon dioxide (PaCO 2), serum EOS and ApoE levels at admission, the ratio of aerosolized inhaled glucocorticoids and non-invasive mechanical ventilation showed statistical differences between the two groups. Multivariate Logistic regression analysis showed that related factors affecting systemic glucocorticoid exposure levels of AECOPD patients with CO 2 retention were FEV1% at stable phase [odds ratio ( OR) = 0.957, 95% confidence interval (95% CI) was 0.921-0.994, P = 0.023], acute exacerbation frequency within 1 year ( OR = 1.530, 95% CI was 1.121-2.088, P = 0.007), heart failure ( OR = 3.022, 95% CI was 1.263-7.231, P = 0.013), PaCO 2 ( OR = 1.062, 95% CI was 1.010-1.115, P = 0.018) and EOS at admission ( OR = 0.103, 95% CI was 0.016-0.684, P = 0.019), aerosolized inhaled glucocorticoids ( OR = 0.337, 95% CI was 0.145-0.783, P = 0.011) and non-invasive mechanical ventilation at acute exacerbation ( OR = 0.422, 95% CI was 0.188-0.948, P = 0.037), of which high FEV1% at stable phase, high EOS at admission, aerosolized inhaled glucocorticoid and non-invasive mechanical ventilation at acute exacerbation were protective factors, while high frequency of acute exacerbation within 1 year, heart failure and high PaCO 2 were risk factors. Conclusions:For AECOPD patients with CO 2 retention, high FEV1% at stable phase, high EOS level at admission, aerosolized inhaled glucocorticoid and non-invasive mechanical ventilation at acute exacerbation can reduce systemic glucocorticoid exposure. In addition, high frequency of acute exacerbation within 1 year, heart failure, and high PaCO 2 can increase systemic glucocorticoid exposure.