PURPOSE: Current diagnostic approach of pleural effusions (PEs) suggests Light’s criteria (Lc) be applied in all patients to determine the exudative or transudative fluid’s nature. In patients with congestive heart failure (CHF) whose pleural fluid meets the exudative criteria, serum-to-fluid protein gradient (PG) >3.1 mg/dl finally categorizes the fluid as transudate. The majority of transudative PEs is due to CHF. Serum B-type natriuretic peptide (BNP) levels >500 pg/ml are considered diagnostic of CHF. We compared the performance characteristics of three approaches, namely Lc aided by PG (Lc-PG), Lc aided by BNP (Lc-BNP) and BNP alone, in the diagnosis of cardiac PEs.
METHODS: All patients hospitalized with PE(s) during a 18-month period were divided into two groups according to the presence (Group A) or absence (Group B) of CHF. The diagnosis of CHF was based on clinical criteria. Serum and pleural fluid LDH, protein and BNP levels were measured in all patients. Performance characteristics of Lc-PG, Lc-BNP and BNP were calculated using chi-square test.
RESULTS: Of the 47 patients enrolled, 18 (38%) were included in Group A and 29 (62%) in Group B. Twelve (67%) of Group’s A effusions were transudates and six exudates, two of the latter having PG >3.1. Group B consisted of 27 exudates and 2 transudates. Serum BNP >500 pg/ml was found in 14 of Group’s A and none of Group’s B patients. Four of the six Group’s A patients with exudative PE had serum BNP >500 pg/ml.
CONCLUSION: Lc-BNP and BNP are superior to Lc-PG-approach for the diagnosis of cardiac PEs. Lc-BNP-approach has the highest sensitivity (89%) and NPV (93%) with an acceptable specificity (93%). The low sensitivity (78%) of BNP-approach discourages its clinical use despite its high specificity (100%).
CLINICAL IMPLICATIONS: For the diagnosis of cardiac PEs, serum BNP seems to be superior to PG in CHF patients with exudative PEs but cannot completely replace Light’s criteria.
DISCLOSURE: Vasileios Skouras, No Financial Disclosure Information; No Product/Research Disclosure Information