Local and systemic effects of a silver nitrate coated indwelling pleural catheter in an animal model of pleurodesis

Purpose/Aim of the study: This study assessed the safety and potential toxicity of a silver nitrate coated indwelling pleural catheter (SNCIPC) designed to create pleurodesis in a large animal model. Materials andMethods: Sixteen animals underwent insertion of either a SNCIPC or an uncoated silicone catheter. Half of the animals were sacrificed at day 7 and the others at day 30. Animal weight and assessment ofwell-being, pleural fluid and blood collectionwere performed at regular intervals. Pleurodesis was assessed at necropsy and histopathological examination of organs performed. Results: No mortality or significant clinical findingswere observed throughout the experiment. SNCIPC treated animals had increased pleural fluid drainage overall (p < 0.001) and specifically on days 1-4. No differences in hemoglobin, white blood cell count or neutrophil countswere detected between groups. No treatment related histological findings were observed in any of the evaluated tissues outside of the treated area. Serum silver levels in SNCIPC catheter treated animals peaked on Day 4 (0.185 mu g/mL, 30 day group) then gradually decreased for the remainder of the study period. The highest tissue silver concentrationswere noted in the SNCIPC groups in tissues close to the treatment site in addition to the liver (59.8ug/g +/-8.6 and 73.3ug/g +/-25). Pleurodesis scores were significantly higher in SNCIPC treated animals for both the 7 day (median 6.5 vs. 1.0, p = 0.029) and 30 day cohorts (median 7.0 vs. 1.5, p= 0.029). Conclusions: SNCIPC arewell tolerated and not associated with any significant signs of toxicity. Silver levels were elevated in local tissues, serum and liver but without evidence of pathological impact. Effective pleurodesis was present by day 7 and more established by day 30. Clinical studies to investigate the safety and efficacy of this device in patients with malignant pleural effusions appear warranted.