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Postoperative gastrointestinal tract dysfunction: An overview of causes and management strategies

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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.


 

References

Tolerance of an enteral diet is one of the fundamental components of postoperative wellness, along with the ability to mobilize freely without supplemental oxygen and a readiness to be discharged home as soon as possible. Accordingly, post­operative gastrointestinal (GI) tract dysfunction is best defined as intolerance of an enteral diet after having been tolerant of one preoperatively. I prefer the term postoperative GI tract dysfunction over postoperative ileus , as ileus is ill defined, covering a wide spectrum of clinical signs and having a range of published incidences so broad (5%–100%) that it defies useful discussion.

Table 1 presents a schema for classifying postoperative GI tract dysfunction. 1 This review focuses on the causes and management of early-onset GI dysfunction—ie, developing within 6 to 48 hours of surgery—which can develop into persistent dysfunction (> 72 hours) and thereby prolong the hospital stay and potentially manifest systemically. This review will not address immediate and transient postoperative nausea and vomiting, which is distinct from intolerance of an enteral diet and has been reviewed extensively elsewhere. 2

GI DYSFUNCTION: A COMMON POSTOPERATIVE MORBIDITY

Postoperative GI tract dysfunction is common, as illustrated by a large prospective cohort study at Duke University Medical Center 3 that used the Postoperative Morbidity Survey (which has since been validated 4) to document complications following major noncardiac surgery (ie, anticipated duration > 2 hours and anticipated blood loss > 500 mL). Hospital discharge was delayed in 27% of the study’s 438 patients as a result of a postoperative complication, and GI dysfunction was the most common type of complication overall and on postoperative days 5, 8, and 15. Episodes of GI dysfunction ranged from intolerance of an enteral diet to ischemic gut resulting in multiple organ failure. 3

Adapted from a PowerPoint slide developed by Dr. M.P.W. Grocott.

Figure 1. Gastrointestinal (GI) tract dysfunction was the most common postoperative complication at both 5 days and 8 days in two large prospective cohort studies of patients undergoing major noncardiac surgery in the United States 3 and the United Kingdom, 4 with rates more than double those of renal or pulmonary complications.

A similar prospective cohort study conducted in the United Kingdom yielded comparable findings, with GI dysfunction being the most common type of postoperative complication reported. 4 This study served to validate the Postoperative Morbidity Survey, which is now used worldwide to describe morbidity after major surgery. Figure 1 presents rates of postoperative GI dysfunction relative to other common types of postoperative complications in both the Duke study and the UK study. 3,4

A MULTIFACTORIAL PATHOGENESIS

The pathophysiology of postoperative GI tract dysfunction can be ischemic, metabolic, toxic, neurogenic, myogenic, pharmacologic, or mechanical.

It is important to recognize that in many cases no single factor explains the whole story behind postsurgical GI tract dysfunction, and none of these factors is an ipso facto cause of such dysfunction. For instance, a “mechanical” pathogenesis refers to any manipulation of the gut that causes an inflammatory response in the gut’s various layers, resulting in injury. 5,6 However, GI tract dysfunction commonly occurs after operations (including laparoscopic procedures) in which the gut was not handled at all. Similarly, in terms of a pharmacologic pathophysiology, while opioids can affect GI propulsion and cause constipation, 7,8 avoidance of opioid use does not ensure prevention of GI tract dysfunction. Moreover, opioid abusers do not generally exhibit intolerance of enteral nutrition.

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