Large pleural effusions occurring after coronary artery bypass grafting

Background: Large pleural effusions sometimes occur after coronary artery b ypass grafting (CABG), but their characteristics and clinical course are la rgely unknown. Objective: To describe the clinical course and pleural fluid findings in pa tients 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 1 997. Measurements: Chest radiographs were reviewed, and information on pleural f luid 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 we re found in 29 patients (0.78%). Seven of the effusions were attributed to congestive heart failure, 2 were attributed to pericarditis, and 1 was attr ibuted to pulmonary embolism. The explanation for the remaining 19 effusion s 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 w ere frequently eosinophilic. Nonbloody effusions tended to be more difficul t to manage. Conclusions: Large pleural effusions may develop in a small proportion of p atients after CABG. The cause of many of these effusions is unclear. Most b loody effusions can be managed with one to three therapeutic thoracenteses. Resolution of nonbloody effusions may require antiinflammatory agents, tub e thoracostomy, or intrapleural injection of sclerosing agents.