Minimizing Diaphragmatic Injury During Radiofrequency Ablation: Efficacy of Intraabdominal Carbon Dioxide Insufflation

Abstract

OBJECTIVE. The purpose of our study was to determine whether intraperitoneal insufflation of carbon dioxide (CO₂) reduces adjacent diaphragmatic injury. MATERIALS AND METHODS. In seven pigs under anesthesia, a 17-gauge percutaneous insufflation needle was inserted in the infraumbilical midline using a standard insufflator. Three to six liters of CO₂ was infused into the peritoneal space to achieve at least a 1-cm separation between the liver and the diaphragm and maintained by a pressure of 8–10 mm Hg. Seven control lesions in six historical controls were used. In addition, five lesions were created in one animal from this cohort who served as a control. Superficial areas of liver separated from diaphragm were fluoroscopically targeted for radiofrequency ablation, and several 2-cm-diameter radiofrequency lesions were generated. The pigs were sacrificed at 48 hr, and at laparotomy, the liver surface was inspected and sectioned to select lesions with centers within 1 cm of the surface. The thermal injury to the corresponding adjacent diaphragm was examined to determine the depth of injury. Diaphragmatic injury was graded on a scale from 0 to III (0, no injury; I, mild injury to one-third thickness; II, moderate injury to two-thirds thickness; III, severe injury to full thickness.) RESULTS. Of 72 total lesions created, 60 had centers less than 1 cm from the liver surface (i.e., superficial) at laparotomy. Of these 60 lesions, 55 caused no significant diaphragmatic injury, two caused grade I injury and three caused grade III injury. In comparison, seven of seven historic superficial control lesions and five of five superficial radiofrequency control lesions from the current cohort caused grade III injury. Superficial radiofrequency lesions created after intraperitoneal CO₂ insufflation caused significantly less (p < 0.01) diaphragmatic injury. CONCLUSION. We have shown that in pigs, intraperitoneal CO₂ insufflation helped significantly reduce severe diaphragmatic injury when superficial hepatic radiofrequency ablation was performed.