[Compensatory increases in residual lobar volume following lung resection].

To investigate compensatory increases in residual lobar volume after lobectomy and pneumonectomy, we measured lung lobar volumes on the basis of pre- and postoperative computed tomographic (CT) images obtained on 40 patients (11 right upper, 7 right lower, 10 left upper, 8 left lower lobectomies and 4 left pneumonectomies). A personal computer image processing program was utilized to calculate lung lobar volumes from sequential CT images. Decreases in whole lung volume after lung resection averaged from 7.4% to 9.5% of preoperative whole lung volume in the lobectomy patients, and 30% in the patients who underwent left pneumonectomy. Those values were much smaller than the volumes of resected lobe, as measured on the basis of preoperative CT images. Increased residual lobar volume after lung resection averaged from 11% to 15% of preoperative whole lung volume in both the lobectomy and left pneumonectomy patient groups. Residual lobes compensated for approximately 60% of the resected lobar volume in the lobectomy patients, but only about 30% of resected lung volume in the left pneumonectomy patients. Increases in residual lobar volume tended to be larger in patients who underwent upper lobectomies, and on the operative side in patients other than those who underwent left lower lobectomies. We concluded that compensatory increases in residual lobar volume should be taken into full consideration when making predictions about postoperative pulmonary function.