The evaluation of pleural effusions in patients with heart failure

PURPOSE: To determine the causes of pleural effusions in patients with heart failure, and the association of the characteristics of these statistics with the use of diuretics. SUBJECTS AND METHODS: Eighty-one patients with a definite diagnosis of heart failure who underwent thoracentesis were evaluated. Fluids were classified as transudates or exudates using Light's criteria. RESULTS: Forty-one effusions (in 34 patients) were transudates, and 54 (in 47 patients) were exudates. Aspecific cause was found for 32 of the exudates (27 patients); except for heart failure, no obvious cause was found for the remaining 22 fluids (20 patients). Euxdates with a specific cause for an exudate were more likely to have at least two of Light's criteria (18 of 27 [67%]) than did exudates without a known cause (2 of 21 [10%]). Intravenous diuretic therapy in the 24 hours before thoracentesis was significantly more common among patients with exudates without a specific cause. CONCLUSIONS: Patients with heart failure may have exudative pleural effusions without an obvious cause except heart failure.