Large pleural effusions occurring after coronary artery bypass grafting

Background: Large pleural effusions sometimes occur after coronary artery bypass grafting (CABG), but their characteristics and clinical course are largely unknown. Objective: To describe the clinical course and pleural fluid findings in patients with large pleural effusions occurring after CABG. Design: Retrospective case series. Setting: Tertiary care, university-affiliated, nonprofit teaching hospital. Patients: 3707 patients who had CABC between 1 February 1996 and 1 August 1997. Measurements: Chest radiographs were reviewed, and information on pleural fluid findings, pleural effusion treatment, and cardiac surgery was obtained from medical records and a cardiac surgery database. Results: Pleural effusions that occupied more than 25% of the hemithorax were found in 29 patients (0.78%). Seven of the effusions were attributed to congestive heart failure, 2 were attributed to pericarditis, and 1 was attributed to pulmonary embolism. The explanation for the remaining 19 effusions was unclear. All but 2 effusions were predominantly left-sided. Of these 19 effusions, 8 were bloody and 11 were nonbloody. Bloody effusions usually occurred earlier, contained higher lactic acid dehydrogenase levels, and were frequently eosinophilic. Nonbloody effusions tended to be more difficult to manage. Conclusions: Large pleural effusions may develop in a small proportion of patients after CABG. The cause of many of these effusions is unclear. Most bloody effusions can be managed with one to three therapeutic thoracenteses. Resolution of nonbloody effusions may require antiinflammatory agents, tube thoracostomy, or intrapleural injection of sclerosing agents.