PURPOSE: Spontaneous pneumothorax is a common problem. If persistent, the treatment often includes tube thoracostomy plus a sclerosant. Common sclerosing agents include antibiotics, talc or blood patch. To histologically define the most efficient pleurodesis agent, a rabbit model was given doxycycline, talc, or autologous blood in the pleural space. Their lungs and chest walls were evaluated for vascular endothelial growth factor (VEGF) and thrombomodulin: important cytokines in angiogenesis, coagulation and fibrinolysis.
METHODS: Rabbits were given talc 70 mg/kg (n=8), doxycycline 10 mg (n=5) or autologous blood 1 ml/kg (n=11). Controls received a chest tube only (n=4). Lungs were harvested at 30 days, histological tissues were stained with antibodies to thrombomodulin and VEGF, and scoring for intensity was guided by an expert pathologist.
RESULTS: Means and standard deviations for pleurodesis-related staining demonstrated: Doxycycline: VEGF 30.0 ± 10.0, thrombomodulin 12.5 ± 10.6 Blood: VEGF 24.4 ± 12.9, thrombomodulin 7.5 ± 3.5 Talc: VEGF 23.3 ± 12.1, thrombomodulin 8.6 ± 3.8 Chest tube:VEGF 8.75 ± 2.5, thrombomodulin 5.0 ± 0.1 Successful pleurodesis on gross examination revealed: doxycycline 66.7%, blood 14.3%, talc 41.7% and chest tube 16.7%. Both proteins stained doxycycline with the highest and chest tube with the lowest score corresponding with pleurodesis on gross examination. Neither stain, however, selected a single sclerosing agent as statistically significant compared to the control (thrombomodulin p=0.07 and VEGF p=0.09).
CONCLUSION: In a pleurodesis model, VEGF and thrombomodulin staining intensity were compared to adhesion of visceral and parietal surfaces on gross necropsy. Thrombomodulin stain intensity by sclerosant group, highest to lowest, was doxycycline, talc, blood, and chest tube. This corresponded with observed physical adhesion. VEGF histology elevated the blood patch over talc.
CLINICAL IMPLICATIONS: As antibodies to thrombomodulin and VEGF are commonly used to identify mesothelial cell upregulation and proliferation, they may not suitably reflect the physiology instituting pleurodesis.
DISCLOSURE: Anthony Hericks, No Financial Disclosure Information; No Product/Research Disclosure Information