BACKGROUND: Evaluate the effects of barium sulphate in rats pleural cavity. METHOD: The effects due to the presence of 100% barium sulphate in the pleural cavity of 43 rats were experimentally assessed. After inhaled ether anesthesia, 1 ml of radiological contrast was injected via subxiphoid through a blunt needle into the right pleural cavity. The animals were divided into 3 groups and were killed with in a closed chamber with ether after 24 hs (13 rats), 48 hs (16 rats) and 21 days (14 rats), respectively. Through a longitudinal sternotomy and laparatomy, both parietal and visceral pleura were extracted along with the rib cage and right lung. Control group was composed of 22 rats which underwent an injection of 1 ml saline 0,9% into the right pleural cavity. RESULTS: No death occurred in 43 rats injected with barium sulphate nor in the control group. There were similar findings in the pleural cavity of animals (barium sulphate) killed at 24h and 48h such as diffuse mild hyperemia in right pleura, free barium sulphate, inflammatory pleural effusion with polymorphonuclears predominating, macrophages phagocyting barium sulphate in the pleura, which presented a polymorphonuclear predominant infiltrate. At 21 days, barium sulphate was found localized and blocked in the retrosternal region with, intense formation of pleural symphises. Pleural histopathology revealed large numbers of barium sulphate filled macrophages, scant extra-cellular barium sulphate pigments, important fibroelastic proliferation in 13/14(92%) cases, without granuloma formation. Histopathology of 22 rats of the control group was considered normal throughout the experiment. CONCLUSIONS: Barium sulphate caused inflammatory pleural effusion in all cases; with no granuloma formation; and no deaths troughout the experiment.
Pleural; Barium sulphate; Pleural symphises