Pleurodesis by autologous blood, doxycycline, and talc in a rabbit model

Background. Management of recurrent spontaneous pneumothorax or symptomatic pleural effusion often uses thoracoscopic pleurodesis, about which many questions remain. Both effectiveness and toxicity of agents currently used for pleurodesis were evaluated in a rabbit model. Methods. Agents administered were autologous blood 1 mL/kg, talc slurry (70 mg • mL−1 • kg−1), and doxycycline 10 mg/mL, given through a chest tube to 30 rabbits. Controls had only chest tubes inserted. At 30 days surfaces were graded by gross observation and histologic examination. Blood and lung tissue from all animals were analyzed for enzymes and blood chemistries. Results. Gross observations showed mediastinal thickening and adhesions with doxycycline, and threadlike adhesions with talc. Autologous blood was only slightly more effective than a chest tube alone. Talc significantly increased angiotensin converting enzyme activity in serum, whereas doxycycline changed liver function enzymes and produced tissue toxicity. Conclusions. Doxycycline produced effective pleurodesis but yielded remarkably severe local effects. The distant sequelae of talc and doxycycline pleurodesis—histologic changes in the contralateral lung and serum enzyme elevations—suggests undesirable systemic effects for the commonly used agents, and autologous blood exhibited no significant pleurodesis, short-term. The search for the ideal agent for chemical pleurodesis continues.