RecruitingComparing the Diagnostic Sensitivity and Specificity of Pleural Fluid N-Terminal Pro B-type Natriuretic Peptide (NT-proBNP) and Other Biochemical Gradient Criteria in Distinguishing Heart Failure and Non-heart Failure Related Pleural Effusions (CENTRE Study)To assess the discriminative properties of pleural fluid (PF) N-terminal-proB-type-natriuretic-peptide (NTproBNP) levels in identifying heart failure (HF)-associated pleural effusions (PE).