Using preset diagnostic criteria, the etiology of each pleural effusion was determined, and the best discriminating level of the serum-effusion albumin gradient between transudates and exudates was established.
Materials and Methods
The subjects were adult consecutive inpatients from the general medicine service or intensive care unit at Nladigan Army Medical Center who had a diagnostic or therapeutic thoracentesis performed between June 1988 and April 1989. The protocol was accepted by the local human utilization review committee. All patients signed a consent form to participate in the study.
The following studies were performed on all pleural fluid samples: albumin; glucose; protein; LDH; cell count; differential cell count; Gram stain; bacterial culture; AFB smear and culture; and cytology. A sample of serum (preferably simultaneous but accepted within 24 hours of thoracentesis) was obtained in order to measure glucose, total protein, albumin, and LDH levels. Further studies, including pleural biopsy, were done at the discretion of the primary physician. The results of the albumin gradient were not used to alter management.
The inpatient chart, outpatient follow-up, and postmortem record (on patients who died shortly after thoracentesis) were reviewed, and a diagnosis was established for the effusion using the following criteria. Congestive heart failure was diagnosed if the patient had an appropriate history and physical findings, some objective evidence of cardiac dysfunction (such as MUG A scan, echocardiography, or cardiac catheterization), a clinical response to diuretics, and other causes were excluded.