Objective: To analyze pulmonary functional changes and pain in patients undergoing off-pump coronary artery bypass grafting utilizing a left internal thoracic artery graft, comparing pleural drain insertion through the intercostal space and the subxyphoid approach.Methods: Twenty-eight patients (mean age 57.4 ± ± ± ± ± 8.4 years) were divided into two groups, according to the pleural drain site. Group LI (n=15) had the pleural drain inserted through the sixth left intercostal space at the mid-axillary line and in the MI group (n=13) the drain was placed through the subxyphoid region. All the patients underwent pre-and postoperative evaluations of pulmonary function tests as well as arterial blood gas analysis. Forced vital capacity (FVC) and forced expiratory volume over one second (FEV 1 ) were recorded in the preoperative period, and on the first, third and fifth postoperative days. The pain sensation was evaluated using a standard score from 0 to 10. Results:In both groups, falls in the FVC and FEV 1 were noted, up to the fifth postoperative day (P<0.001). However the decrease was higher in the LI group, when compared to the MI group (p<0.05). Also arterial blood gas analysis showed a decline of the partial oxygen pressure in both groups on the first postoperative day, but more significantly in the LI group (p=0.021). The pain sensation was higher in the LI group (p=0.002).Conclusion: Off-pump coronary artery bypass grafting using the left internal thoracic artery, disregarding the pleural drain site, leads to a significant decrease of postoperative pulmonary function. However, the subxyphoid technique of drain insertion has shown a better preservation of the lung function when compared to the intercostal drain site.Descriptors: Coronary artery bypass surgery. Pleural drain. Pulmonary function. 48GUIZILINI, S ET AL -Effects of the pleural drain site on the pulmonary function after coronary artery bypass grafting Bras Cir Cardiovasc 2004; 19(1): 47-54 Rev