Postoperative gastrointestinal tract dysfunction: An overview of causes and management strategies
ABSTRACT
Postoperative gastrointestinal (GI) tract dysfunction is common and has a complex, multifactorial pathogenesis. Perioperative administration of targeted amounts of fluid to optimize ventricular filling and end-organ perfusion has consistently been shown to improve mortality and other outcomes, particularly GI tract perfusion and function. The choice of fluid loading affects postoperative recovery, with colloid showing superiority over crystalloid, and lactated Ringer’s solution proving better than normal saline. Other methods of reducing postoperative GI tract dysfunction with some proven degree of success include simple, low-cost interventions such as early initiation of oral feeding, early use of laxatives, and gum chewing. There is no evidence that prophylactic nasogastric decompression accelerates return of bowel function.
KEY POINTS
- GI tract dysfunction is the most common type of postoperative morbidity and frequently delays hospital discharge.
- Low-grade hypovolemia leading to gut ischemia is a common but neglected mechanism of postoperative GI tract dysfunction.
- Administration of colloid to achieve target levels of cardiac output improves gut perfusion and lowers the incidence of GI tract dysfunction.
- Doppler-guided fluid management reduces GI morbidity and length of hospital stay in surgical patients.
DISCUSSION
Question from the audience: You mentioned the selective use of nasogastric tubes. In which patients would you use them?
Dr. Mythen: For upper GI surgeries—esophagectomy, for example—a nasogastric tube is inevitable. Beyond that, the specific indications for tube placement are very limited. At our institution, we no longer place nasogastric tubes following the vast majority of GI tract operations, with esophagectomy being the exception.
Question from the audience: Would you comment on the selective contribution of thoracic epidural analgesia with respect to early feeding after abdominal or colon surgery?
Dr. Mythen: If you’re an enthusiast for thoracic epidurals, you can present the literature in a way that definitively demonstrates a huge advantage to thoracic epidurals. When they work well for the individual, they are fantastic, but you must have a very effective team and system to deliver success to the whole patient population. At our institution the failure rate 20 to 24 hours postoperatively is about 50%.
Question from the audience: I’m an internist and I’ve never heard of the esophageal Doppler-directed fluid bolus protocol—or of anyone using colloids at all. Is that something that is generally practiced in the United States?
Dr. Mythen: Some institutions are practicing goal-directed fluid management now. If you measure stroke volume and give small boluses of colloid, you need a lot less fluid to achieve a higher intravascular volume and goal. At our institution, we’ve repackaged it as “goal-directed fluid restriction” to gain acceptance among surgeons. Uptake has been slower in the United States, though studies here have reinforced the message and been supported by editorials. Guessing about fluids, which we’ve done historically, is not very smart. One thing that differentiates an anesthesiologist from an anesthetic technician is the ability to give goal-directed fluid therapy. The ability to act in a targeted fashion makes it possible to achieve an appropriate physiological goal, but it is more difficult.
Question from the audience: In terms of maintenance fluids and chloride toxicity, is there an alternative to D5 half-normal saline for maintenance fluid?
Dr. Mythen: We don’t have a very good postoperative maintenance fluid; D5 half-normal with some potassium is probably as good as it gets at present. I emphasize getting patients to drink as quickly as possible. If they’re not drinking (not using the GI tract), they need a very high level of physician input because fluid balance is rocket science. The GI tract is very clever. Once patients are drinking and eating, they’re fine, but if they still have an intravenous line in, close attention is required.
Question from the audience: Would you use lactated Ringer’s solution in a patient who is just not eating or drinking?
Dr. Mythen: I do, actually. I tend to mix it in with some D5 half-normal saline because lactated Ringer’s is a great solution. The body can use the lactate to make sugar if necessary. The brain is one of the few organs that will metabolize lactate.
Follow-up question: Would you use it at a lower rate to prevent volume overload?
Dr. Mythen: Yes, at 60 mL/hr. The important thing is that if intravenous fluids are still required, the patient needs to be in a fairly supervised, high-dependency environment. You must address the real issue: Why aren’t they drinking? If the patient is not drinking postoperatively, someone’s done a bad job or there is something that needs fixing.
Question from audience: In the operating room, do you have a preference between albumin and a high-molecular-weight hetastarch like Hextend?
Dr. Mythen: Europe is slightly different in its choice of colloids. We’ve pretty much abandoned the high-molecular-weight starches. We do not use albumin at our institution for cost reasons, and we can’t find any evidence to support its use. We would have to close one intensive care unit bed to be able to afford using albumin. We use low-molecular-weight hydroxyethyl starches, which I believe are now coming into the United States. They have no major coagulation effect.
