In the critically ill or injured patient, gut dysfunction commonly occurs and can take various forms, from food intolerance to life-threating conditions that can progress to multiple organ dysfunction syndrome (MODS) or persistent inflammatory, immunosuppressed, catabolic syndrome (PICS).
Gut injury can be described as an ischemia/reperfusion event that can present as severe as nonocclusive small bowel ischemia to the abdominal compartment syndrome.
More commonly, gastrointestinal (GI) dysfunction will manifest as gastroesophageal reflux, gastroparesis, duodenogastric ileus, or malabsorption as a manifestation of food intolerance.
Recognition of the human microbiome as an important component of gut health and the alterations in the microbiome during critical illness has spurred renewed interest in the microbiology of the GI tract.
The chapter will review the pathophysiology and the current best practice recommendations for medical management.
In the critically ill or injured patient who survives the initial 48 hours in the intensive care unit (ICU), multiple organ dysfunction syndrome (MODS) and multiple organ failure (MOF) are the leading causes of death in the ICU (see Chapter 63). First, there is strong evidence that during the early stages of shock and reperfusion, episodes of abdominal compartment syndrome (ACS) and gut hypoperfusion can lead to organ dysfunction and death.1-3 Second, there is growing evidence that the gut microbiome changes soon after injury. The proximal gut, which is typically sterile, develops heavy colonization that can be harmful. These bacteria can have harmful effects on the gut homeostasis and barrier function.4-12 Third, gut-focused medical therapies such as selective gut decontamination, early enteral nutrition, and most recently immune-enhancing enteral diets have been shown to reduce these nosocomial infections.6,13-18 The focus of this chapter is to provide an overview of the gut dysfunction of the injured and critically ill patient and how it contributes to overall morbidity and mortality. The discussion will then focus on the pathogenesis and clinical monitoring of specific gut dysfunctions. Based on this information, potential therapeutic strategies to prevent and/or treat gut dysfunction to enhance patient outcome will be discussed.
HOW GUT DYSFUNCTION CONTRIBUTES TO ADVERSE PATIENT OUTCOME
MOF results from a dysfunctional, hyperinflammatory response producing two distinct patterns (ie, early vs late) (see Chapter 57). Soon after a traumatic insult, patients are found to be in a state of systemic hyperinflammation, referred to as the systemic inflammatory response syndrome (SIRS).19-21 The intensity of SIRS is dependent upon (1) innate host factors (genotype/phenotype), (2) the degree of shock, and (3) the amount of tissue injured (mechanism of injury). Of the three, shock is the predominant factor that produces a maladaptive, overexuberant SIRS response.22,23 The inflammatory response to injury is an evolutionary developed, expected, and maintained response in all organisms. Mild-to-moderate SIRS is most likely beneficial and probably necessary at some basic physiologic level. Severe ...