Silver nitrate is superior to talc slurry in producing pleurodesis in rabbits

Study objective: The ideal agent for producing pleurodesis has not been ide ntified, Although tale is the agent most commonly used at the present time, there are concerns about its safety. Silver nitrate is a possible alternat ive agent. The purpose of the present study was to compare the effectivenes s of intrapleural silver nitrate and talc slurry in producing pleurodesis i n rabbits, Additionally, the total amount of pleural collagen and the distr ibution of thick and thin collagen fibers were studied. Design: Two groups of 10 rabbits received either 0.50% silver nitrate or 40 0 mg/kg talc in a total volume of 2 mL intrapleurally. The animals were kil led 28 days after injection, and the pleural spaces were assessed grossly f or evidence of pleurodesis and microscopically for evidence of inflammation and fibrosis, Collagen was assessed with the van Gieson's and picrosirius stains. Results: The macroscopic pleurodesis (scale, 0 to 4; mean +/- SEM) resultin g from the intrapleural injection of silver nitrate (3.4 +/- 0.2) was signi ficantly better (p < 0.001) than that resulting from talc (1.6 +/- 0.1). Th e mean degree of microscopic pleural fibrosis induced by silver nitrate (3. 3 +/- 0.3) was significantly higher (p = 0.003) than that induced by talc ( 1.8 +/- 0.1). The mean amount of microscopic pleural collagen (van Gieson's ) was significantly greater (p < 0.001) in the rabbits that received silver nitrate (3.0 +/- 0.2) than in those that received talc (1.6 +/- 0.2). The distribution of thick and thin collagen fibers did not differ between the g roups. Conclusions: We conclude that, in our rabbit model, intrapleural silver nit rate was more effective than talc in producing a pleurodesis.