Is the reduction of forced expiratory lung volumes proportional to the lung parenchyma resection, 6 months after pneumonectomy?

Abstract

To preoperatively estimate the degree of first-second forced expired volume (FEV1) and forced vital capacity (FVC) reduction 6 months after pneumonectomy, according to the preoperative performed spirometry and bronchoscopy, and to estimate if the expected postoperative values of FEV1 and FVC are in accordance with the actual values. Thirty-five patients, who underwent pneumonectomy for non-small cell lung cancer between 1996 and 1999, were included in the perspective study. All patients had total or near total bronchial obstruction at preoperative bronchoscopy. Patients were divided into three groups according to the preoperative bronchoscopy findings: Group I, obstruction of the main bronchus (six patients); Group II, obstruction of a lobar bronchus (19 patients); and Group III, obstruction of a segmental bronchus (10 patients). The estimation of the percent reduction of FEV1 and FVC has been made according to the formula: percent reduction=(no. of bronchopulmonary segments to be resected-no. of obstructed segments) x 5.26%. The mean overall actual percent reduction of FEV1 and FVC differed significantly from the expected mean overall percent reduction of FEV1 and FVC (P=0.000 and P=0.001, respectively). The actual values were lower than the predicted values using the given formula. In group and subgroup analysis, the mean actual percent reduction of FEV1 and FVC differed significantly from the mean expected percent reduction of FEV1 and FVC in Groups I and II of patients (P<0.01), but no significant differences were observed in Group III of patients (P>0.05). No significant differences between expected and actual mean percent reduction of FEV1 and FVC was also observed in patients of Groups I and II, when lung or lobar atelectasis, respectively, was noted at preoperative chest X-ray (P>0.05). Only when a segmental bronchus was obstructed at the preoperative bronchoscopy or when lobar or lung atelectasis was the result of the main or lobar bronchus obstruction, the estimated, using the proposed formula, expected percent reduction of FEV1 and FVC values were close to the actual postoperative percent reduction of FEV1 and FVC.