The effect of postoperative change in bronchial angle on postoperative pulmonary function after upper lobectomy in lung cancer patients

Upper lobectomy inevitably leads to an upward displacement of the remaining lower lobe. Such displacement may result in bronchial angulation, thereby narrowing the airway. We hypothesized that the degree of displacement of the bronchus is associated with the degree of exacerbation of postoperative pulmonary dysfunction. This study investigated whether bronchial angulation affects postoperative pulmonary function. Patients undergoing upper lobectomy for lung cancer were retrospectively evaluated. A check for the presence of dyspnoea, pulmonary function test, chest X-ray and chest computed tomography (CT) were performed at 3 and 12 months postoperatively in these patients. The angle formed by the main bronchus and the bronchus intermedius on the right side and that by the main bronchus and the lower lobar bronchus were measured using the coronal view of the chest CT. We analysed the relationship between the change in bronchial angle and pulmonary function. Ninety-nine patients were enrolled in this study. Among these patients, 50 underwent left upper lobectomy (LUL) and 49 underwent right upper lobectomy (RUL). Nine patients who underwent LUL showed worsening symptoms, and among them, 8 presented an increase in the angle. However, among the 9 patients with worsening symptoms after RUL, only 4 presented an increase in the angle. Decreased forced expiratory volume in 1 s (FEV1) from 3 to 12 months after surgery was observed in 16 patients in the LUL group and 14 in the RUL group. Exacerbation of pulmonary dysfunction was associated with an increase in the bronchial angle (P = 0.04 for LUL and P = 0.02 for RUL). The degree of angle change was also associated with the extent of FEV1 reduction (P = 0.02 for LUL and P = 0.02 for RUL). Although the change in the bronchial angle is a physiological condition, it can reduce postoperative pulmonary function. The measurement of the change in the angle using the coronal view of a chest CT is a useful screening tool for predicting the postoperative reduction in FEV1.