In their series of 5 patients undergoing POEM, Swaanstr?m et al. observed the development of pneumoperitoneum in 3 patients and placement Bicalutamide clinical of a Veress needle was necessary to decompress it [46]. According to the authors, Inoue described this occurrence as well in 10% of this most recent series of more than 100 patients (personal communication) and theorized that it might occur due to gas permeation through the remarkably thin longitudinal muscle fibers of the esophagus [46]. 5. Infection Prevention Since the beginning of NOTES procedures, sterility has been a hurdle. Infection must be prevented by using a clean access site. Most transesophageal protocols follow a 12�C24-hour liquid formula diet, intravenous antibiotics and esophageal and stomach irrigation with saline or iodopovidone solution.

Despite these precautions, even a sterile overtube used to protect the endoscope from oral contamination becomes contaminated on oral insertion and can transport bacteria to the esophagus, the mediastinum, and the thorax. Several infectious complications have been reported. In a study by Fritscher et al. two out of 12 pigs had reflux of gastric contents into the esophagus that resulted in spillage through the esophagotomy [28]. The study protocol included 12-hour fasting period before surgery and a 3-day antibiotherapy with enrofloxacin. Despite this, one animal died of severe mediastinitis, whereas the other one developed a subclinical mediastinal abscess found on necropsy. The authors suggested that careful aspiration of gastric contents at the beginning of the procedure should always be performed.

Also, the authors concluded that 12 hours of fasting may be too short time to clear the stomach of the animals well enough. In a previous study by Gee et al., one out of four animals developed submucosal abscess, despite 24h liquid diet, esophagus and stomach lavage with iodopovidone solution and cefazolin injection preoperatively [14]. There is also some controversy about the need for endoscope sterilization. In a recent literature review, Spaun et al. concluded that, although difficult, it is possible to terminally sterilize flexible endoscopes. Steris System 1TM that uses 0.2% peracetic acid was the cheapest and fastest sterilization method and scored second in the risk of recontamination. Ethylene oxide gas (ETO) sterilization has the lowest risk of recontamination but is the slowest and most expensive method.

The authors recommend sterile instrumentation for clinical NOTES until well-designed and randomized clinical trials are available and guidelines are published [47]. When transferring the results from animal experiments to human settings, one should keep in mind that anatomy and physiology of the esophagus and the mediastinum in humans are somewhat different from those Dacomitinib of the pig, especially with regard to wall structure, motility, and infection pathophysiology of the mediastinum.