We studied eight patients with typical clinical and roentgenographic findings of heart failure. We took care not to include patients in whom another etiology for pleural effusion might coexist. Patients with isolated left-sided pleural effusion were excluded, since this is an uncommon finding in heart failure. Pleural effusions responded to the treatment of heart failure. Long-term follow-up was available in all patients and did not reveal any other coexistent pleural disease. The criteria we used for selecting patients were very similar to the ones used by Light et al for the diagnosis of congestive heart failure in their study of pleural efiusions. add comment
Treatment of congestive heart failure and its effect on pleural chemistry was prospectively evaluated using the pleural fluid levels of LDH and protein and the pleural fluid/serum ratios for LDH and protein. To the best of our knowledge, there is no other study in the literature which has done such measurements. The pleural fluid levels of protein and LDH and the pleural fluid/serum ratios for LDH and protein increased significantly with the treatment of congestive heart failure. The criteria of Light et al, which are described in the results section, are commonly used to differentiate exudates from transudates. The presence of any one of the three criteria would classify the pleural fluid as an exudate. Using these criteria, three patients had pleural effusions that were transudates at the initial study but met criteria for an exudate at the final study. The rise in the pleural fluid level of protein was more impressive in our study, compared to those reported many years ago. This may be explained by the fact that the diuretics used today are much more potent than the ones used in the past.
One patient (case 1) had a pleural fluid LDH level of 282 units/L at the initial study. We believe that this was from the markedly elevated serum level of LDH of 794 units/L. In this patient, after treatment of heart failure, the pleural fluid level of LDH rose 64 percent, even though the serum level of LDH decreased 38 percent.