Effect of artificial ascites on thermal injury to the diaphragm and stomach in radiofrequency ablation of the liver: Experimental study with a porcine model

OBJECTIVE. The purpose of this study was to evaluate the effect of artificial ascites on thermal injury to the diaphragm and stomach in a porcine model of radiofrequency ablation of the liver. MATERIALS AND METHODS. We performed this study using eight pigs in experimental and control groups of four pigs each. Artificial ascites was produced before radiofrequency ablation to separate the liver from the diaphragm and the stomach in the experimental group. Using a 1-cm exposed internally cooled radiofrequency electrode for 5 minutes, we performed 74 hepatic ablations abutting the diaphragm and stomach. CT was performed on the day of the procedure and 7 days after ablation. The pigs were sacrificed, and necropsy was performed. We performed pathologic and CT examinations to compare the frequency and extent of thermal injury to the two organs. RESULTS. The mean number of radiofrequency ablations in each pig was 9.3 (range, 6 - 12). The mean number of ablation zones adjoining the diaphragm was 5.5 (range, 3 - 8) and of zones contiguous with the stomach was 3.8 (range, 3 - 4). Thermal injury to the adjacent organs occurred more frequently in the control group than in the experimental group (p < 0.05). The major complications of diaphragmatic hernia and gastric perforation occurred only in the control group. No major complications were identified in the experimental group at necropsy. The sizes of the radiofrequency ablation zone of the liver did not differ between the two groups (p > 0.05). The mean diameters of the diaphragmatic and gastric lesions did differ (p < 0.05). Histopathologic examination revealed a significant difference in the depths of thermal injury in the two groups (p < 0.05). CONCLUSION. Artificial ascites may be a simple and useful technique for reducing the frequency and severity of collateral thermal injury to the diaphragm and stomach during radiofrequency ablation of subcapsular hepatic tumors.