Intrapleural low-dose silver nitrate elicits more pleural inflammation and less systemic inflammation than low dose talc

Study objectives: Several systemic effects have been described after tale pleurodesis. The aim of this study was to assess the systemic response induced by low, nonpleurodesis-inducing doses of tale and silver nitrate in an experimental model in rabbits. Design: Groups of six rabbits were injected intrapleurally with tale, 100 mg/kg or 400 mg/kg, and silver nitrate, 0.1% or 0.5%. After 6, 24, or 48 h, samples of blood and pleural fluid were collected and assayed for leukocytes, percentage of neutrophils, lactate dehydrogenase, interleukin-8, and vascular endothelial growth factor (VEGF) levels. Preinjection blood samples were used as normal blood controls. Measurements and results: Silver nitrate 0.1% induced a more intense pleural inflammation than that produced by tale 100 mg/kg. In contrast, tale 100 mg/kg induced a more pronounced acute systemic response with higher values of WBCs and neutrophils, whereas silver nitrate 0.1% produced no significant increases in leukocytes or neutrophils. The serum interleukin-8 and VEGF levels, increased in all groups, and decreased with time only in the silver nitrate 0.1% group. The highest serum VEGF levels were observed in the tale 160 mg/kg group. Conclusions: In conclusion, 0.1% silver nitrate produced an intense pleural inflammatory response with a less evident systemic response in comparison to 0.5% silver nitrate and tale 100 mg/kg or 400 mg/kg.