Anesthetic Routines: The Anesthesiologist's Role in GI Recovery and Postoperative Ileus

Abstract

All patients undergoing bowel resection experience postoperative ileus, a transient cessation of bowel motility that prevents effective transit of intestinal contents or tolerance of oral intake, to varying degrees. An anesthesiologist plays a critical role, not only in the initiation of surgical anesthesia, but also with the selection and transition to effective postoperative analgesia regimens. Attempts to reduce the duration of postoperative ileus have prompted the study of various preoperative, perioperative, and postoperative regimens to facilitate gastrointestinal recovery. These include modifiable variables such as epidural anesthesia and analgesia, opioid-sparing anesthesia and analgesia, fluid restriction, colloid versus crystalloid combinations, prokinetic drugs, and use of the new peripherally acting mu-opioid receptor (PAM-OR) antagonists. Review and appropriate adaptation of these multiple modifiable interventions by anesthesiologists and their surgical colleagues will facilitate implementation of a best-practice management routine for bowel resection procedures that will benefit the patient and the healthcare system.

Figure 1

The multifactorial etiology of postoperative ileus (POI). Development of POI is multifactorial. Surgical incision and manipulation of the intestines activate inflammatory and stress responses and endogenous opioids. Mast cells release vasoactive substances diffusing into blood vessels. These substances increase mucosal permeability, allowing entrance of luminal bacteria or LPS into lymphatics or interaction with resident macrophages. Damaged tissue also activates macrophages, increasing expression of proinflammatory genes. Stress causes macrophages to release chemokines and inflammatory cytokines, which attract leukocytes to the intestinal muscularis. Large amounts of nitric oxide and prostaglandins are released, which impair smooth muscle contraction. Endogenous opioids are released, which disrupt GI transit and motility. Exogenous opioid analgesia also disrupts GI motility.