PURPOSE: The literature suggests that a substantial number of pleural effusions on initial diagnostic thoracentesis are undiagnosed or problematic. These effusions may be the result of more than one cause (physiologic processes).
METHODS: Analysis from 300 consecutive pleural effusions obtained from our pleural fluid database from 2001 to 2003, were reviewed. All pleural fluid analyses (PFA) included total protein, LDH, cell count with differential, glucose, pH , and triglycerides; amylase, cytology and microbiology were done in the appropriate clinical setting. PF/Serum protein > 0.5 or LDH > 2/3 of upper limit of normal serum LDH were considered exudates. The diagnosis was established after review of the history, chest imaging, blood work and PFA by 2 experts in pleural disease. The primary and secondary causes of the effusions were determined from the patients’ course.
RESULTS: Of the 300 patients evaluated, 223 (74%) were inpatients and 77 (26%) were outpatients.34 (11%) patients were found to have two diagnoses to explain the PFA; 31 (91%) were inpatients and 3 (9%) were outpatients. The most common underlying diagnosis was congestive heart failure 17 (50%) followed by malignancy 10 (29%). The most frequent concomitant diagnoses were pneumonia 10 (29%), spontaneous bacterial pleuritis 4 (12%), and trauma 4 (12%), followed by trapped lung/lung entrapment 3 (9%) and chylothorax 3 (9%).
CONCLUSION: Problematic PFA may require further review of the clinical history and laboratory findings to establish a diagnosis. We found that these effusions are secondary to two distinct pathophysiologic processes. Of these effusions with dual diagnoses, congestive heart failure and malignancy were the two most common primary diagnoses with infection being the most common concomitant diagnosis. Hospitalized patients are more likely to have a pleural effusion with more than one cause.
CLINICAL IMPLICATIONS: When clinicians encounter a problematic effusion, especially in the hospitalized patient, a dual diagnosis needs to be considered. Pleural effusions presumed to be caused by congestive heart failure, particularly in the inpatient setting, often have a concomitant cause to explain problematic pleural fluid analysis.
DISCLOSURE: Vishal Agrawal, No Financial Disclosure Information; No Product/Research Disclosure Information