Which parameters might predict complications after natural orifice endoluminal surgery (NOTES)? Results from a randomized comparison with open surgical access in pigs

Background and study aims: Natural orifice transluminal endoscopic surgery (NOTES) is currently developed and assessed mainly in pig experiments. The vast majority of studies show a good outcome in short-term follow-up. The current study aims at comparing various parameters of postinterventional assessment and surveillance in relation to clinical behavior and autopsy results to find suitable control parameters and also to assess the pig as suitable model for NOTES compared with open surgery.

Methods: Within the framework of a randomized prospective study of 20 pigs with iatrogenic colonic perforation comparing endoscopic with open surgical closure, clinical examination, including observation of behavior, food intake, and body temperature, was carried out daily. Laboratory parameters (white blood cells [WBC], granulocytes) were measured in 14 animals. Weight was measured preoperatively and on days 2 and 7 postoperatively. Results were matched with complications found during/after 2 weeks’ survival. Pre-autopsy sterile cultures were taken from the peritoneal cavities to determine possible bacterial contamination.

Results: Three animals from the surgical group were sacrificed on days 4, 8, and 12 because they became severely ill, with autopsy revealing intussusception from adhesions, peritoneal abscess, and peritonitis, in one pig each; another animal had culture positive for Escherichia coli. Three minor complications (2 cough, 1 continuing fever with adhesions to the bladder found on autopsy) occurred in the endoscopic group without compromised recovery. WBC were measured in 14 animals, and found to be elevated (8 - 36 × 10⁹/l) in six on day 2 including the two animals with severe complications. Between pre- and post-procedure, WBC increased about twofold in the uneventful cases but fourfold in the two animals with severe complications. Cultures from the abdominal cavity before autopsy were negative in all but one animal.

Conclusion: Animal behavior was a reliable indicator of severe complications. Fever, body weight, and the results of in vitro cultures of the peritoneal fluid did not indicate complications. WBC proved not to be specific but showed a larger increase in pigs with severe complications.

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