Site of pleural drain insertion and early postoperative pulmonary functionfollowing coronary artery bypass grafting with internal mammary artery

Study objectives: Coronary artery bypass graft (CABG) surgery using the lef t internal mammary artery (LIMA) impairs postoperative pulmonary function. We studied the changes in pulmonary function and subjective pain relative t o the site of chest tube insertion. Design: Thirty patients undergoing CABG surgery using the LIMA were randomi zed into two groups. Group A (n = 15) received a left chest tube inserted f rom the midline (subxyphoid). Group B (n = 15) had a tube placed in the six th intercostal space at the anterior axillary line. All of the patients und erwent bedside pulmonary function testing preoperatively and on postoperati ve 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 obse rved in both groups until POD 5. For group A, the decline in percent predic ted (+/-SD) in the vital capacity (VC) from before surgery to POD 5 was, re spectively 92.3 +/- 30.8% to 56.9 +/- 12.6% (p < 0.001). For group B, the d ecline 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 50.5 +/- 12. 1%, and in group B from 83.5 +/- 16.4% to 53.9 +/- 12.5% (p < 0.001). On PO D 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 si gnificantly lower decrease in the FEV1 was also seen in group A than in gro up B, respectively: 36.9 +/- 12.9% vs 28.0 +/- 10.6% (p < 0.05). Pain exper ienced 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 significa ntly lower impairment of pulmonary function and less subjective pain than i nsertion at the intercostal position. The drainage of the left pleural spac e is equally effective with both techniques.