Natural-orifice transluminal endoscopic surgery: low-pressure pneumoperitoneum is sufficient and is associated with an improved cardiopulmonary response (PressurePig Study) - Delius, S. von; Schorn, A.; Grimm, M.; Schneider, A.; Wilhelm, D.; Schuster, T.; Stangassinger, M.; Feussner, H.; Schmid, R. M.; Meining, A. (Endoscopy, 2011)