Thoracentesis in the bilateral pleural effusion. Should we puncture both sides? Prospective study

Introduction: In the absence of strong recommendations, analyze if in bilateral pleural effusion is enough to puncture one side or it is necessary puncture both. Material and methods: Prospective study (for 3 years and 9 months) of consecutive patients with bilateral pleural effusion who underwent simultaneous bilateral thoracentesis. In patients with suspected heart failure were punctured only those with asymmetric pleural effusion, or who had chest pain or fever. The parameters analyzed were common in the protocol of our institution. We also evaluated the pleural effusion size, the presence of chest pain or fever, the existence of lung abnormalities, the different attenuation values in chest CT, the presence of pleural loculations and the radiological resolution. Results: 36 patients (19 men; mean age 68.5 ± 16.5 years) were studied. Only 2 patients (5.6%) the etiology of the effusion was different on both sides. The final diagnosis of the pleural effusion did not correspond with the biochemical fluid analysis in 6/32 cases (18.8%). The correlation between the biochemical parameters analyzed in the pleural effusion on both sides [Pearson correlation coefficient (R2)] ranges from 0.53 (LDH) and 0.996 (NT-proBNP). There was no association between clinical-radiological features or between biochemical determinations of the pleural effusion and the different etiologies of pleural effusion or different diagnostic groups (transudate / exudates). Conclusions: It does not seem advisable perform routinely simultaneously bilateral thoracentesis. Larger studies are needed to establish what factors may suggest the need for puncturing both pleural cavities.