Background: A predicted postoperative forced expiratory volume in 1 second (FEV1) of less than 800 ml or 40% of predicted is a common criterion for exclusion of patients from lung resection for cancer. Usually, the predicted postoperative lung function is calculated according to a formula based on the number of lung segments that will be resected. Incentive spirometry and specific inspiratory muscle training are two maneuvers that have been used to enhance lung expansion and inspiratory muscle strength in patients with chronic obstructive pulmonary disease and after lung operation.
Methods: Thirty-two patients with chronic obstructive pulmonary disease who were candidates for lung resection were randomized into two groups: 17 patients received specific inspiratory muscle training and incentive spirometry, 1 hour per day, six times a week, for 2 weeks before and 3 months after lung resection (group A) and 15 patients were assigned to the control group and received no training (group B).
Results: Inspiratory muscle strength increased significantly in the training group, both before and 3 months after the operation. In group B, the predicted postoperative FEV1 value consistently underestimated the actual postoperative FEV1 by approximately 70 ml in the lobectomy subgroup and by 110 ml in the pneumonectomy subgroup. In group A, the actual postoperative FEV1 was higher than the predicted postoperative FEV1 by 570 ml in the lobectomy subgroup and by 680 ml in the pneumonectomy subgroup of patients.
Conclusions: In patients undergoing lung resection the simple calculation of predicted postoperative FEV1 underestimates the actual postoperative FEV1 by a small fraction. Lung functions can be increased significantly when incentive spirometry and specific inspiratory muscle training are used before and after operation.