Stimulation of the autonomic nervous system in colorectal surgery: a study protocol for a randomized controlled trial

Background: Postoperative ileus (POI) is a well-known complication of abdominal surgery and is considered to be caused by a local inflammation in the gut. Previously it has been shown that both local and systemic inflammation can be reduced by stimulation of the autonomic nervous system via lipid rich nutrition. Stimulation of the autonomic nervous system releases acetylcholine from efferent vagal nerve endings that binds to nicotinic receptors located on the inflammatory cells leading to a decrease of pro-inflammatory mediators. Besides administration of nutrition there are other ways of stimulating the autonomic nervous system such as gum chewing. Methods/design: This prospective, placebo-controlled randomized trial will include 120 patients undergoing colorectal surgery which are randomized for gum chewing preoperatively and in the direct postoperative phase or a placebo. Postoperative ileus will be assessed both clinically by time to first flatus and time to first defecation and by determination of gastric motility using ultrasound to measure dimensions of the antrum. Furthermore the inflammatory response is quantified by analyzing pro-inflammatory mediators. Finally, markers of gut barrier integrity will be measured as well as occurrence of postoperative complications. Discussion: We hypothesize that chewing gum preoperatively and in the direct postoperative phase in patients undergoing colorectal surgery dampens local and systematic inflammation, via activation of the autonomic nervous system. Down-regulation of the inflammatory cascade via stimulation of the vagus nerve will ameleriote POI and enhance postoperative recovery.