Study objectives: To determine whether talc (TL) and silver nitrate (SN), two effective pleurodesis agents, induce a systemic inflammatory response in the acute phase of experimental pleurodesis in rabbits.
Design: Samples of blood and pleural fluid were collected after 6, 24, and 48 h from rabbits injected intrapleurally with 3 mL saline solution, TL (400 mg/kg), or 0.5% SN, and were assayed for WBC count, percentage of neutrophils, and levels of lactate dehydrogenase (LDH), interleukin (IL)-8, and vascular endothelial growth factor (VEGF). The pleural liquid production was compared in the three different groups. A sample of blood collected from animals preinjection was used as the control.
Results: At 6 h after pleural injection, the mean blood WBC count and percentage of neutrophils were significantly elevated in the TL group, whereas the mean LDH and IL-8 levels were significantly increased in the SN group. VEGF was undetectable in the preinjection serum and saline solution-injected animals, but was increased in the serum after the pleural injection of both TL and SN to a comparable degree. SN elicited a more intense acute pleural inflammation reaction than did TL, with higher WBC count and IL-8 levels found in the pleural fluid, mainly within the first 6 h. LDH and VEGF levels, and pleural liquid production were also higher for SN, and they increased with time.
Conclusions: In the acute phase of pleural injection, TL induced a transient increase in blood WBC count and percentage of neutrophils, while SN induced increases in blood LDH and IL-8 levels. Both TL and SN induced significant increases in blood VEGF levels. SN induced an earlier and more intense acute pleural inflammation than TL. Pleural liquid VEGF levels were higher after SN injection and increased, as did pleural liquid production. These findings suggest that the intrapleural injection of TL and SN produce a systemic inflammatory response that may have a role in the pathogenesis of fever and ARDS, which occur with pleurodesis.