Abstract: Objective The aim of this study was to investigate prevalence and risk factors of pulmonary infection in patients with acute-on-chronic liver failure (ACLF). Methods 89 patients with ACLF were enrolled in our hospital between January 2020 and January 2024, and their clinical materials were retrospectively analyzed. The occurrence of pulmonary infection and short-term prognosis were recorded. Model for end-stage liver disease and serum sodium (MELD-Na) was calculated, multivariate Logistic regression analysis was applied to evaluate risk factors of pulmonary infection, and receiver operating characteristic (ROC) was used to predict prognosis. Results 31 patients (34.8%) had pulmonary infection among 89 patients with ACLF. In our series; the proportion of age older than 65 years, concomitant diabetes mellitus, invasive operation rate and long-term antibiotic use in patients with pulmonary infection group were 61.3%, 19.4%, 61.3% and 32.3%, all significantly higher than 32.8%, 1.7%, 34.5% and 10.3% (P<0.05), while serum albumin level was (29.3±4.2)g/L, much lower than [(33.8±4.9)g/L, P<0.05] and MELD-Na score was (30.5±2.5)points, much higher than [(27.1±2.0)points, P<0.05] in those without pulmonary infection; hospital stay, 28 d and 90 d mortality were (29.8±3.1)d, 41.9% and 51.6%, all much longer or greater than [(21.2±2.7)d, 12.1% and 15.5%, respectively, P<0.05] in those without pulmonary infection; Logistic regression analysis revealed that age older than 65 years [OR=2.457, 95%CI (1.283-4.707), P<0.05], diabetes mellitus [OR=2.807, 95%CI (1.579-4.990), P<0.05], invasive operation [OR=3.071, 95%CI (1.776-5.311), P<0.05], long-term antibiotic administration [OR=2.983, 95%CI (1.727-5.154), P<0.05], serum albumin level lower than 31.2 g/L [OR=4.289, 95%CI (2.779-6.619), P<0.05] and MELD-Na score greater than 29.0 points [OR=3.927, 95%CI (2.487-6.203), P<0.05] were all the independent risk factors for pulmonary infection; ROC analysis showed that serum albumin and MELD-Na score had statistical implication in predicting pulmonary infection in ACLF patients (AUC=0.949, AUC=0.912, P<0.05). Conclusion The risk of pulmonary infection is higher in ACLF patients. Surveillance of serum albumin levels and MELD-Na score might help clinicians take an appropriate measures to deal with it.

Key words: Acute-on-chronic liver failure, Pulmonary infection, Model for end-stage liver disease and serum sodium, Risk factors, Prognosis