Postoperative starvation after gastrointestinal surgery

The widespread practice of starving patients in the immediate period after gastrointestinal surgery has been challenged by a systematic review and meta-analysis in this issue (p 773), which finds that “nil by mouth” after gastrointestinal surgery may not be beneficial.¹ Further, the apparently beneficial effects of early postoperative enteral feeding on infection rates and length of stay in hospital are compelling arguments in favour of a change in clinical practice.

The rationale of nil by mouth and gastric decompression is to prevent postoperative nausea and vomiting and protect the anastomosis, allowing it time to heal before being stressed by food. Nausea and vomiting, however, occur more commonly after upper gastrointestinal surgery than after resection of the small intestine and colon. In our clinical experience nasogastric decompression can usually be discontinued 12-24 hours after resection of the small intestine and colon.

There is no evidence that bowel rest and a period of starvation are beneficial for healing of wounds and anastomotic integrity. Indeed, the evidence is that luminal nutrition may enhance wound healing and increase anastomotic strength, particularly in malnourished patients.²,³

The findings of the meta-analysis, however, raise some important questions. Should early postoperative feeding be restricted to patients with pre-existing malnutrition; is its efficacy related to the degree of surgical injury; and is the main site of action of luminal nutrition the level of the intestinal barrier?

Pre-existing malnutrition has been shown to be a major clinical problem in surgical patients.⁴ Although several factors—age, coexisting disease, type and extent of surgical procedure, blood loss, duration of procedure, skill of the surgeon, and the disease itself—have been shown to be associated with postoperative complications, nutritional depletion is an independent determinant of serious complications after major gastrointestinal surgery.⁵ Surgical injury itself increases resting energy expenditure and protein loss, and intake of energy and protein after gastrointestinal surgery fall well below what is required throughout the stay in hospital.⁶,⁷ Understandably, the advocates of early postoperative enteral feeding have therefore often focused on its use in malnourished patients.

Pre-existing nutritional depletion, however, may not be the only nutritional factor associated with postoperative complications after gastrointestinal surgery. Two recent studies on postoperative enteral feeding showed that nutritional support was associated with a significant reduction in postoperative complications, a reduction that was independent of preoperative nutritional status.⁷,⁸

The benefits of postoperative enteral feeding in normally nourished surgical patients indicate that it is reduced nutritional intake that predisposes patients to developing complications, including deficits in muscle function and surgical fatigue.⁷ There is thus no evidence that early postoperative enteral feeding should be restricted to malnourished patients undergoing gastrointestinal resection. Indeed, one study has found that supplementing “normal” oral diet in hospital wards with as little as 1250 kJ (300 kcal) and 12 g of protein per day resulted in a reduction of postoperative complications in patients undergoing gastrointestinal surgery.⁷ Therefore, there may be a threshold of nutritional intake which, if not achieved, may predispose some patients to postoperative complications.⁹

As the authors have pointed out, the randomised trials they identified were heterogeneous as to underlying diagnosis and type of surgery. Ten of 11 studies reported the site of surgery. Importantly, in all but two studies most patients underwent lower gastrointestinal surgery. In the two studies in which patients underwent major upper gastrointestinal surgery, early postoperative enteral nutrition either afforded no advantages over standard care or seemed to have a deleterious effect.¹⁰,¹¹

One explanation of these results might be that the surgical injury is less and the metabolic response to it relatively modest in patients undergoing lower gastrointestinal surgery, compared with patients undergoing major upper gastrointestinal surgery. Only in patients undergoing lower gastrointestinal surgery does enteral nutrition in the early postoperative period have an important impact.

Recently, changes in intestinal permeability have been shown in patients undergoing gastrointestinal surgery, increased permeability being associated with sepsis and systemic inflammation.¹² Bacterial translocation has also been shown in patients undergoing laparotomy, and a higher proportion of patients with bacterial translocation developed sepsis than those without.¹³ There is, however, no evidence in humans that increased intestinal permeability correlates with bacterial translocation or that early postoperative enteral nutrition influences intestinal permeability or reduces the incidence of bacterial translocation. The appealing hypothesis that early postoperative luminal nutrition might have a beneficial effect on the function of the intestinal barrier in respect of permeability, bacterial translocation, and the subsequent development of septic complications has no supporting evidence at present.

What impact could the findings of this systematic review have on daily surgical practice? The review shows that there is no clinical benefit to starving patients in the early postoperative period after gastrointestinal resection. Further, the finding that postoperative infections can be reduced and hospital stay shortened by starting early postoperative enteral nutrition should challenge clinicians to consider this treatment. The findings pave the way for an appropriate multicentred trial to assess early enteral feeding in patients undergoing elective gastrointestinal resection. The patients recruited to such a trial should be stratified by nutritional status and type of surgical procedure. The outcome measures should include not just effects on wound infection, other infectious complications, and dehiscence of the anastomosis but also surgical fatigue, muscle function, quality of life after discharge from hospital, and cost effectiveness.

Papers p 773