KEY POINTS
For many years, a single standard of care governed the prevention of postoperative ileus following cesarean delivery and other abdominal surgeries; now it appears the thinking behind that strategy is outdated.- Rather than contributing to ileus, early postoperative feeding now appears to help diminish its occurrence.
- There is no justification for routine postoperative placement of nasogastric tubes in asymptomatic patients.
- Thoracic epidurals block the reflex that causes postoperative ileus and can be used to prevent its occurrence.
Traditionally, the routine approach to avoiding this complication consisted of placing a nasogastric (NG) tube to decompress the bowel and delaying feeding until bowel function resumed.
More recent studies indicate that a different tactic may be preferable. These suggest that postoperative ileus—which has an estimated annual cost of $750 million1—can be significantly reduced with a simple 3-step process:
- withholding the nasogastric (NG) tube,
- feeding the patient early in the recovery process, and
- continuing epidural local anesthesia postoperatively.
Pathogenesis of ileus
We now know that the return of bowel function following surgery is an orderly event. The return of the small intestine’s action begins first, usually 4 to 8 hours postoperatively, and generally becomes complete around 24 hours. The colon resumes its function between 48 and 72 hours postoperatively.2
Very little has been written about the pathogenesis of postoperative ileus, but multiple causes have been suggested: sympathetic reflexes; inhibitory humoral agents; release of norepinephrine from the bowel wall; and the effects of anesthesia agents, opiates, and inflammation.3 The 2 most frequently mentioned etiologies are:
- the inhibitory neural reflex and
- inflammatory mediators released from the site of injury. (Inflammation is thought to trigger the release of macrophages, cytokines, and other inflammatory mediators, causing neutrophil infiltration.4)
Controversy remains as to what actually initiates the ileus. Is it manipulation of the bowel or the rigors of surgery and anesthesia? Kalff et al6 conducted bowel muscle studies in rats and concluded that manipulation of the bowel—and not the laparotomy per se—causes a failure of gut circular muscle function 24 hours later. They also noted an increase of phagocytes and mast cells. Their data support the hypothesis that abdominal surgery initiates a cascade of inflammatory events that leads to postoperative ileus.2
The case for early feeding
In the past 10 years, several studies have demonstrated that—rather than reduce the incidence of ileus—inserting an NG tube and withholding regular feeding following abdominal surgery can cause an ileus or prolong a preexisting one. Other trials have shown that feeding a patient early in the postoperative period can actually prevent ileus.7,8
Physiologic studies have shown that neither electrical activity of the bowel nor motor activities in the stomach are affected by surgery.8 Schilder et al9 reported bowel activity before the passage of flatus, indicating that the bowel is on its way to recovery much earlier than had been assumed. Thus, early postoperative feeding is well tolerated in most patients and associated with reduced discomfort and a more rapid recovery.7
For example, MacMillan et al studied 139 women undergoing gynecologic surgery for benign conditions; 67 were randomized to “early” feeding and 72 to traditional management. Early feeding involved a low-residue diet given 6 hours postoperatively, while traditional feeding consisted of clear liquids, which were withheld until the return of normal bowel sounds. Patients progressed to a regular diet with the passage of flatus. No increase in gastrointestinal complaints occurred in the early feeding group.7
Pearl et al8 compared similar groups of patients (TABLE 1). Patients in the first group were fed a clear liquid diet on the first postoperative day and progressed to a regular diet as soon as it could be tolerated. The traditional group was not fed until the return of bowel function, which was defined as the passage of flatus and no abdominal distension or vomiting; they were then started on clear liquids and, later, solid foods. While the incidence of complications was the same in both groups, hospitalization was shorter in the early feeding group.
A Cochrane review compared early versus delayed oral fluids and food after cesarean delivery. Of 12 studies considered, 6 were included in the review. No evidence was found to justify a policy of withholding oral fluids after uncomplicated cesarean sections.5
Simple versus complex procedures. Early feeding is not only safe in standardized surgeries such as cesarean section, but extends to complicated surgeries as well, as demonstrated in the trials by MacMillan et al7 and Pearl et al,8 which involved major gynecologic surgery. Trials with gynecologic oncology patients have shown the same result.2,8 Even patients undergoing colorectal surgery can tolerate oral feeding very early in their postoperative course without bowel complications.2,8