Peritoneal inflammatory response of natural orifice translumenal endoscopic surgery (NOTES) versus laparoscopy with carbon dioxide and air pneumoperitoneum

Background The immunologic and physiologic effects of natural orifice translumenal endoscopic surgery (NOTES) versus traditional surgical approaches are poorly understood. Previous investigations have shown that NOTES and laparoscopy share similar inflammatory cytokine profiles except for a possible late-phase tissue necrosis factor-α (TNF-α) depression with NOTES. The local peritoneal reaction and immunomodulatory influence of pneumoperitoneum agents in NOTES also are not known and may play an important role in altering the physiologic insult induced by NOTES. Methods In this study, 51 animals were divided into four study groups, which respectively underwent abdominal exploration via transgastric NOTES using room air (AIR) or carbon dioxide (CO₂) or via laparoscopy (LX) using AIR or CO₂ for pneumoperitoneum. Laparotomy and sham surgeries were additionally performed as control conditions. Measurements of TNF-α, interleukin-1β (IL-1β), and IL-6 were performed for peritoneal fluid collected after 0, 2, 4, and 6 h and on postoperative days (PODs) 1, 2, and 7. Results Of the 45 animals assessed, 6 were excluded because of technical operative complications. The findings showed that LX-CO₂ generated the most pronounced response with all three inflammatory markers. However, no significant differences were detected between LX-CO₂ and either NOTES group at these peak points. No differences were encountered between NOTES-CO₂ and NOTES-AIR. Subgroup comparisons showed significantly higher levels of TNF-α and IL-6 with NOTES-CO₂ than with LX-AIR on POD 1 (p = 0.022) and POD 2 (p = 0.002). The LX-CO₂ subgroup had significantly higher levels of TNF-α than the LX-AIR subgroup at 4 h (p = 0.013) and on POD 1 (p = 0.021). No late-phase TNF-α depression occurred in the NOTES animals. Conclusion The local inflammatory reaction to NOTES was similar to that with traditional laparoscopy, and the previously described late-phase systemic TNF-α depression in serum was not reproduced. At the peritoneal level, NOTES is no more physiologically stressful than laparoscopy. Furthermore, regardless of which gas was used, the role of the pneumoperitoneum agent did not affect the cytokine profile after NOTES, suggesting that air pneumoperitoneum is adequate for NOTES.