Postoperative ileus

The investigators are testing the hypothesis that lower pressure pneumoperitoneum during laparoscopic large bowel surgery protects the bowel from postoperative ileus and bowel dysfunction leading to faster recovery and discharge from the hospital. Our study will focus on the effects of high or low intraperitoneal pressure as well as pressure variations on the course of postoperative ileus, time to hospital discharge, and postoperative gastrointestinal dysfunction in adult patients undergoing laparoscopic large bowel resection (i.e., sigmoidectomy and right colectomy). A randomized parallel group study will be conducted involving 5 arms of surgical patients to test whether differences on postoperative ileus outcome parameters occur between high (15 mm Hg) and low pressure pneumoperitoneum (8-12 mm Hg), as well as whether there are differences between the 2 insufflation devices that provide constant or variable intrabdominal pressure throughout the laparoscopic surgery. For high pressure pneumoperitoneum, either neostigmine or sugammadex are used for reversal of moderate neuromuscular blockade. For low pressure pneumoperitoneum, sugammadex is used for reversal of deep neuromuscular blockade. The investigators plan to use 2 types of gas insufflation devices, one of which will provide a relatively stable pressure level throughout surgery (AirSeal® device), and the second one will provide a more variable pressure (Olympus standard insufflation device). Using both pressure modalities, the investigators will study the effects of different pressure characteristics on the course of postoperative ileus, duration of in-hospital treatment, pain level, and the stability of hemodynamic and respiratory parameters during surgery. Changes in intrabdominal pressure during the surgery will be monitored and recorded using a custom software for later analysis of fluctuations in pressure to relate them to outcomes. Other parameters will be obtained from EPIC (IHIS) medical charts. In addition, clinical data on postoperative ileus will be correlated with experimental outcomes from in vitro exploratory studies done using human samples of peritoneal lavage fluid, serum, and a small portion of the surgically removed bowel from each patient (that is otherwise discarded). A panel of inflammatory markers will be analyzed and biochemical, imaging, histological, immunochemical, molecular signaling, and glial activation studies will be done to evaluate the potential mechanisms of dysfunction associated with postoperative ileus.