To evaluate the value of lung ultrasonography (LUS), right heart echocardiographic parameters, and related clinical indicators in evaluating severe pulmonary fibrosis (PF).

This is a cross-sectional study that included 107 patients with PF treated at Tangdu Hospital of Air Force Medical University from March 2024 to January 2025, among whom 49 were divided into a non-severe PF group and 58 into a severe PF group. All patients underwent LUS assessment and transthoracic echocardiography, and relevant clinical indicators were also collected. The clinical data and ultrasonic characteristic parameters of the two groups were compared. Logistic regression analysis was used to identify the independent risk factors for severe PF. The receiver operating characteristic (ROC) curve was used to assess the diagnostic efficacy of each independent risk factor and their combination for severe PF.

There were statistically significant differences in age, proportion of males, and smoking history between the two groups (all P＜0.05). Compared with the non-severe group, erythrocyte sedimentation rate, cytokeratin 19 fragment level, LUS score, and pleural line thickness were significantly increased in patients with severe PF (all P＜0.05), while the proportion of patients with impaired right ventricular relaxation function, tricuspid annular plane systolic excursion/systolic pulmonary arterial pressure ratio＜0.55 mm/mmHg, and tricuspid regurgitation velocity＞2.8 m/s was higher in the severe group (P＜0.05). In addition, the severe group also showed characteristics of greater pulmonary artery diameter and increased pulmonary vascular resistance. Multivariate Logistic regression analysis showed that smoking (odds ratio [OR]=17.48, 95% confidence interval [CI]: 1.47-207.84, P=0.024), impaired right heart relaxation function (OR=9.52, 95%CI: 1.25-72.80, P=0.03), pulmonary artery diameter (OR=1.72, 95%CI: 1.11-2.68, P=0.016), LUS score (OR=1.17, 1.01-1.35, P=0.034), and pleural line thickness (OR=21.22, 95%CI: 4.28-105.21, P<0.001) were independent risk factors for severe PF. The area under the ROC curve (AUC) of the combined model incorporating the above five factors was 0.97, and its diagnostic efficiency was better than that of single indicators.

This study confirms that smoking, impaired right heart relaxation function, greater pulmonary artery dilation, high LUS score, and pleural line thickening are closely related to severe PF. The combination of LUS and right heart echocardiography can be used as a new method for the assessment and dynamic monitoring of PF severity.