Pleural effusion is a common complication of cardiac surgery. The aim of this study was to determine the prevalence, characteristics and determinants of clinically significant pleural effusions, defined as those requiring therapeutic pleural drainage.

This was a retrospective cohort study of prevalence and characteristics of patients who had a pleural effusion after coronary artery bypass graft, valve replacement or both procedures.

Information was collected on all consecutive patients who underwent CABG surgery and/or valve replacement between January 1, 2004 and December 31, 2005. Demographic information, anthropometric parameters, cardiac and renal function assessments, and comorbid conditions were retrieved from medical files. We also collected data on the type of procedure, whether it was elective or urgent, the number and origin of the grafts, the duration of surgery and of cardiopulmonary bypass and the postoperative complications, including pleural effusions. Clinical presentation and evolution of the effusions as well as pleural fluid characteristics were also studied.

Patients were considered to have a clinically significant pleural effusion when they met at least one of the following criteria: need for thoracentesis, a pleural drainage tube or a hospital readmission due to a pleural effusion that occurred within one year of surgery.

Inclusion Criteria:

• Coronary artery bypass grafting (CABG)
• Valve replacement
• Combined CABG and valve replacement
• between January 1st, 2004 and December 31st, 2005

Exclusion Criteria:

• Previous CABG
• Pulmonary and/or aortic artery surgery
• Heart or lung transplant
• Pleural effusion present at the time of surgery

Patients undergoing coronary artery bypass grafting surgery, heart valve replacement surgery or both procedures.