3637 Efficacy of submucosal saline injection in the limitation of colonic thermal injury by electrosurgical devices.

Abstract

Many colonoscopic therapies involve cutting or coagulation effects via delivery of thermal injury. Complications of these techniques include symptomatic transmural burn (post-polypectomy syndrome) and perforation. Submucosal saline injection (SMSI) has been advocated as a means of limiting depth of injury. The saline cushion acts as a heat-sink and increases transmural distance from burn to serosa. However, data are lacking regarding the efficacy of SMSI in limiting depth of thermal injury. Aim: To determine, in a porcine model, the effect of SMSI on depth of thermal injury to the colon due to a various modalities. Methods: Laparotomy under general anesthetic was performed and a longitudinal colotomy incision made on the antimesenteric side. Burns were made using bipolar goldprobe (20W, 2sec), heater probe (HP; 30J); monopolar (MP) contact with biopsy forceps (20W, 2sec), and MP non-contact with argon plasma coagulation (APC; 45W, 3sec); n ≥11 for each lesion. Burns were with or without prior injection of 2mL saline. The incision was closed and animals killed at 24hrs. Lesions were excised for histologic analysis. Injury was assessed by severe damage to the deep (longitudinal) muscle layer. Results: Non-SMSI lesions resulted in deep muscle injury in 86%, 61%, 50% and 18% for APC, MP contact, HP & bipolar, respectively. SMSI reduced risk of deep injury for APC and HP, but not monopolar contact (86%→21%; 50%→0% & 61%→50%, respectively). Conclusions: At equivalent energy outputs, bipolar current results in less deep injury than MP current or HP. Prolonged coagulation with the APC (45W) results in deep colonic injury. At the settings used, saline injection limits depth of injury due to both heater probe and APC, but not monopolar contact cautery. In spite of SMSI, caution should be used with prolonged monopolar cautery. Many colonoscopic therapies involve cutting or coagulation effects via delivery of thermal injury. Complications of these techniques include symptomatic transmural burn (post-polypectomy syndrome) and perforation. Submucosal saline injection (SMSI) has been advocated as a means of limiting depth of injury. The saline cushion acts as a heat-sink and increases transmural distance from burn to serosa. However, data are lacking regarding the efficacy of SMSI in limiting depth of thermal injury. Aim: To determine, in a porcine model, the effect of SMSI on depth of thermal injury to the colon due to a various modalities. Methods: Laparotomy under general anesthetic was performed and a longitudinal colotomy incision made on the antimesenteric side. Burns were made using bipolar goldprobe (20W, 2sec), heater probe (HP; 30J); monopolar (MP) contact with biopsy forceps (20W, 2sec), and MP non-contact with argon plasma coagulation (APC; 45W, 3sec); n ≥11 for each lesion. Burns were with or without prior injection of 2mL saline. The incision was closed and animals killed at 24hrs. Lesions were excised for histologic analysis. Injury was assessed by severe damage to the deep (longitudinal) muscle layer. Results: Non-SMSI lesions resulted in deep muscle injury in 86%, 61%, 50% and 18% for APC, MP contact, HP & bipolar, respectively. SMSI reduced risk of deep injury for APC and HP, but not monopolar contact (86%→21%; 50%→0% & 61%→50%, respectively). Conclusions: At equivalent energy outputs, bipolar current results in less deep injury than MP current or HP. Prolonged coagulation with the APC (45W) results in deep colonic injury. At the settings used, saline injection limits depth of injury due to both heater probe and APC, but not monopolar contact cautery. In spite of SMSI, caution should be used with prolonged monopolar cautery.