Upper lobectomy was the independent factor that caused a greater reduction in postoperative lung function. This was deducible from the upward movement of residual lobes caused by releasing inferior pulmonary ligament. In case with left upper lobectomy, more dramatic postoperative pulmonary changes were developed compared with after right upper lobectomy, due to larger volume it has. We aim to analyze the bronchial deformation associated with the postoperative lung function in the setting of inferior pulmonary ligament dissection.

Patients who underwent left upper lobectomy between January 2021 and March 2023 were divided into two groups based on whether the inferior pulmonary ligament was dissected or preserved. Geometric data of the airways were assessed using a 3-dimensional model. To identify the impact of geometric changes on lung function, the relationship between bronchial deformation, cross-sectional area, and forced expiratory volume was analyzed to identify the impact of geometric changes on lung function. Inverse probability of treatment weighting was used to adjust for selection bias.

Left lobar bronchus twist, cross-sectional area reduction ratio, and forced expiratory volume reduction ratio were significantly higher in the Dissection group than in the Preservation group before and after inverse probability of treatment weighting. After adjustment, the twist of the left lobar bronchus was a significant predictor of cross-sectional area and forced expiratory volume reduction ratio in the Dissection group.

Inferior pulmonary ligament dissection during left upper lobectomy can lead to twist of the left lobar bronchus following cross-sectional area reduction, thereby causing pulmonary dysfunction.