PULMONARY-FUNCTION AFTER CORONARY-ARTERY BYPASS-SURGERY

Coronary artery bypass graft surgery (CABG) adversely affects pulmonar y function tests (PFTs). Although several previous studies have addres sed these changes, none has measured the forced vital capacity (FVC) o n a daily basis. The purpose of the present study was to assess serial changes in the FVC following CABG and to identify factors that may in fluence these changes, The FVC was obtained pre- and daily postoperati vely (1-10 days) in 120 patients. Fifty-one patients received saphenou s vein grafts (SVG group) while 69 received at least one internal mamm ary artery graft in addition to SVG (IMA group). On the first postoper ative day, the FVC decreased to 33% of the pre-operative value in the SVG group and to 29% in the IMA group. The spirometry gradually improv ed, but after 10 days, the FVC remained reduced (SVG, 70%; IMA, 60%). Although the decreases in FVC tended to be greater in the IMA group, t here was no significant difference in the two groups (P=0.27). The cha nges in FVC were not significantly related to age (P=0.48), smoking hi story (P=0.65), anesthesia (P=0.38) or pump time (0.09). From this stu dy, it is concluded that after CABG, there is a significant worsening of the pulmonary function. The nadir of FVC occurs immediately after s urgery and improves gradually thereafter. However, on the tenth postop erative day, the FVC still remains more than 30% below pre-operative v alues. Since there is only a slight tendency for patients undergoing I MA grafting to have larger decreases in their pulmonary function, pati ents with ventilatory impairment should not be excluded from IMA graft ing.