Before operation, forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and peak expiratory flow rate (PEFR), were measured. On the morning before surgery, the patients will be instructed in the use of the PCA pump and a VAS. The patients will be asked to rate their experienced pain using the VAS from 0 to 100 mm with 0 representing no pain and 100 representing the worst imaginable pain.