Site of pleural drain insertion and early postoperative pulmonary function following coronary artery bypass grafting with internal mammary artery.
STUDY OBJECTIVES
Coronary artery bypass graft (CABG) surgery using the left internal mammary artery (LIMA) impairs postoperative pulmonary function. We studied the changes in pulmonary function and subjective pain relative to the site of chest tube insertion.


DESIGN
Thirty patients undergoing CABG surgery using the LIMA were randomized into two groups. Group A (n = 15) received a left chest tube inserted from the midline (subxyphoid). Group B (n = 15) had a tube placed in the sixth intercostal space at the anterior axillary line. All of the patients underwent bedside pulmonary function testing preoperatively and on postoperative days (PODs) 1, 3, and 5. Pain sensation was quantified by a standardized score (1 to 10).


RESULTS
A significant impairment of pulmonary function parameters was observed in both groups until POD 5. For group A, the decline in percent predicted (+/-SD) in the vital capacity (VC) from before surgery to POD 5 was, respectively, 92.3+/-30.6% to 56.9+/-12.6% (p < 0.001). For group B, the decline in the VC was from 88.0+/-18.2% to 55.5+/-14.8% (p < 0.001). The FEV1 declined concomitantly in group A from 86.2+/-18.2% to 50.8+/-12.1%, and in group B from 83.5+/-16.4% to 53.9+/-12.5% (p < 0.001). On POD 1, a significantly lower decrease in the VC was measured in group A than in group B, respectively: 45.3+/-15.5% vs 28.6+/-8.7% (p < 0.001). A significantly lower decrease in the FEV1 was also seen in group A than in group B, respectively: 36.9+/-12.9% vs 28.0+/-10.6% (p < 0.05). Pain experienced during deep inspiration was also significantly less in group A than in group B, respectively: 1.2+/-1.1 vs 2.5+/-0.9 (p < 0.01).


CONCLUSIONS
Subxyphoid insertion of the pleural drain leads to a significantly lower impairment of pulmonary function and less subjective pain than insertion at the intercostal position. The drainage of the left pleural space is equally effective with both techniques.