Right Middle Lobe Transposition after Upper Lobectomy: Influence on Postoperative Pulmonary Function

Abstract

The aim of the present study was to determine the prevalence of anatomical transposition of the remaining right middle lobe after right upper lobectomy and the effect of this transposition on postoperative global pulmonary function. We correlated the postoperative pulmonary anatomical change with the functional change in patients undergoing right upper lobectomy for lung cancer. To estimate the regional pulmonary function, we measured the regional volume of the lung using normal lung attenuation values (- 600 to - 910 Hounsfield units), known as the functional lung volume, by computed tomography. The position of the middle lobe was objectively evaluated using volume-rendering three-dimensional computed tomography lung models. Intraoperatively, middle lobes were not fixed with the lower lobes. Postoperatively, the middle lobe remained attached to the anterobasal segment in 24 patients, whereas it migrated cranially in the remaining 26 patients. The functional volume of the middle lobe changed by various degrees postoperatively (range: 9 to 171% of preoperative values, mean: 96 ± 34%), and this change was significantly associated with the global pulmonary function (R = 0.5, p = 0.01). However, there were no significant differences between patients with and without middle lobe migration with respect to the postoperative functional volume of the middle lobe, the postoperative functional volume of the total lung, and global pulmonary function. Right middle lobe transposition after upper lobectomy is not associated with the deterioration of pulmonary function, but unexpected deflation of the right middle lobe is. Strategies for preventing middle lobe deflation should be explored in the clinical setting.