Compensation of pulmonary function after upper lobectomy versus lower lobectomy

Objective: Major lung resection may induce expansion of the remaining lung, accompanied by some gain in the function of this lung; however, the impact of the site of resection on this compensatory response remains unclear. Methods: We measured computed tomography-based functional lung volume, representing normal lung attenuation (-600 to -910 Hounsfield units), and spirometry-based lung function (forced expiratory volume in 1 second) preoperatively and 6 months postoperatively in patients with lung cancer and compared them between patients undergoing upper lobectomy (n = 34) and patients undergoing lower lobectomy (n = 26). Results: We removed 17% +/- 4% of the functional lung volume by upper lobectomy and 27% +/- 5% by lower lobectomy (P < .001). Postoperatively, the residual lung expanded by various degrees, accompanied by a proportionate gain in the residual lung function (R = 0.6, P < .001). This anatomic and functional compensation of the residual lung was more remarkable after lower lobectomy than after upper lobectomy (P < .05). Consequently, the percentage loss of the functional lung volume after upper lobectomy (10% +/- 10%) did not differ significantly from that after lower lobectomy (9% +/- 12%, P = .6). Likewise, the percentage loss of lung function after upper lobectomy (12% +/- 16%) did not differ significantly from that after lower lobectomy (14% +/- 17%, P = .6). Conclusions: Although the lower lobectomy implies greater resection than the upper lobectomy, lung function after lower lobectomy was not inferior to that after upper lobectomy because the compensatory response appeared more robust after lower lobectomy. (J Thorac Cardiovasc Surg 2011; 142: 762-7)