To analyze the relevant clinical factors associated with atelectasis following ultrasound-guided percutaneous catheter drainage (PCD) in lung cancer patients complicated with malignant pleural effusion (MPE), and to evaluate the impact of atelectasis on patient prognosis.

A retrospective selection was made of 114 lung cancer patients with malignant pleural effusion (MPE) who underwent ultrasound-guided percutaneous catheter drainage (PCD) in our hospital from June 2021 to March 2024 as the subjects. They were grouped according to the lung expansion status after PCD: 18 cases with atelectasis were included in the observation group, and 96 cases without atelectasis were included in the control group. The clinical data, imaging results, and overall survival of the two groups were compared, and the risk factors for atelectasis were analyzed by regression analysis.

In the observation group, the lactate dehydrogenase( LDH) level [828.30(694.24, 909.56)], pleural fluid-to-serum LDH ratio [1.88 (1.38, 4.00)], endobronchial lesions [9 cases(50.00%)], time from diagnosis of MPE to PCD [7.00 (5.00, 11.00)] days, and drainage volume [850.00 (600.00, 1 000.00)]ml showed statistically significant differences compared with the control group, which had LDH [547.30(460.20, 669.50)], pleural fluid-to-serum LDH ratio [1.18 (0.47, 2.21)], endobronchial lesions 20 cases(20.83%), time from MPE diagnosis to PCD [4.00 (2.00, 7.00) ]days, and drainage volume [1 215.00 (950.00, 1 535.00)]ml (P<0.05). Logistic regression analysis revealed that the pleural fluid-to-serum LDH ratio (OR=2.228, 95%CI: 1.359~3.652), endobronchial lesions (OR=5.076, 95%CI: 1.488~17.317), and time from MPE diagnosis to PCD (OR=1.108, 95%CI: 1.010~1.215) were risk factors for atelectasis in lung cancer patients with MPE (P<0.05). The receiver operating characteristic AUC for predicting post-PCD atelectasis in lung cancer patients with MPE was 0.833 (95%CI: 0.716~0.949), with a Hosmer-Lemeshow test P-value of 0.564. By the end of follow-up, 27 patients (23.68%) were alive and 87 patients (76.32%) had died. The overall survival in the observation group was 79.0 days (IQR: 56.4~103.8 days), which was shorter than that in the control group (99.2 days, IQR: 73.1~142.7 days) (log rank=5.491, P=0.019). COX regression analysis indicated that ECOG-PS ≥ 2, distant metastasis, serum CRP, pleural fluid-to-serum LDH ratio, and atelectasis were risk factors for death in lung cancer patients with MPE (P<0.05).

The pleural effusion-serum LDH ratio, endobronchial lesions, and the time from MPE diagnosis to PCD can predict the occurrence of atelectasis. Atelectasis affects the overall survival of lung cancer patients with MPE after PCD treatment.