Left pleural effusion after coronary artery bypass decreases with a supplemental pleural drain

Background. This prospective study was undertaken to determine the incidence of symptomatic left pleural effusion after coronary artery bypass grafting, and to determine if routine drainage of the pleural cavity with a supplemental flexible drain reduces this incidence. Methods. The clinical course of study patients was prospectively recorded during the initial hospitalization and at 6-weeks after surgery. All patients had a mediastinal and a left pleural tube, which were removed on the 1st postoperative day. The supplemental drain system was implanted in a subset of patients and remained in place for 3 to 5 days. A symptomatic effusion was defined as one that required thoracentesis, tube thoracostomy, or readmission for treatment. Results. A total of 460 patients were studied, of whom 115 had a supplemental drain. The two groups (supplemental drain versus control) were equivalent with respect to age, gender distribution, and comorbid diseases. The incidence of symptomatic left pleural effusion for the entire group was 9.8% (45 of 460). Symptomatic left pleural effusion occurred in 11.9% (41 of 345) patients when only chest tubes were used, and in 3.5% (4 of 115) when a supplemental drain was placed. This difference was significant (F ratio 7.583, p < 0.005). There were no complications from the supplemental drain. Conclusions. The incidence of symptomatic left pleural effusion can be greatly reduced with the use of a supplemental pleural drain that remains in place for several days after surgery.