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Background: Safety is a concern in natural orifice transluminal endoscopic surgery (NOTES) mediastinoscopy. The objective of this study was to compare the safety of NOTES mediastinoscopy with video-assisted mediastinoscopy (VAM). Methods: Twenty-four pigs were randomly assigned to NOTES or VAM. Thirty-minute mediastinoscopies were performed with the identification of seven predetermined structures. The animals were euthanized after 7 days and necropsy was performed. Results: Mediastinoscopy was not possible in one animal in each group. There were more intraoperative adverse events with NOTES than VAM (7 vs. 2, P = 0.04); hemorrhage was the most frequent adverse event (4 and 1, respectively). At necropsy, pathological findings were observed in 13 animals (9 NOTES and 4 VAM; P = 0.03). Inflammatory parameters were not different between groups and were not related to adverse events. Conclusion: Systematic NOTES mediastinoscopy is possible and comparable to VAM in terms of number of organs identified and inflammatory impact. However, the safety profile of NOTES mediastinoscopy has to be improved before it can be adopted in a clinical setting.

Background and study aims Endoscopic resection requires use of submucosal injection. This study was conducted to assess efficacy and impact on early healing of hyaluronic acid combined with chondroitin sulfate and poloxamer 407 (Ziverel) when used as a solution for submucosal injection. Materials and methods Prospective and comparative study of gastric endoscopic mucosal resection (EMR) with three groups of two Yorkshire pigs. Six submucosal cushions were created in each animal by injecting 2 mL of Ziverel (Group 1) or succinylated gelatin (SG) (Group 2), enabling 12 EMR in each group. Submucosal cushions were created with Ziverel in Group 3, without resection. Electrosurgery unit settings were the same in all cases. EMR defects and injection sites were marked with clips. The animals were sacrificed 7 days later. EMR specimen size and duration of procedure were recorded. EMR specimens and EMR scars and injection sites were evaluated by a blinded pathologist. Results We successfully performed 24 EMR (15 en-bloc and 9 piecemeal, without differences between groups 1 and 2). Mean EMR specimen dimensions were significantly larger in Group 1 (median 19 mm, range 6 – 40 vs 16.6 mm, range 5‑25; P = 0.019), without changing the electrocautery unit settings. Blinded histopathologist assessment of EMR specimens showed less fibrosis in the submucosa and a trend to fewer cautery artifacts with Ziverel and did not identify any significant differences in early healing of resection sites. Conclusion The combination of Ziverel enables EMR and does not negatively affect early healing.