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  • The timing, dose, composition, and route of nutritional support influence the outcomes of critically ill patients.

  • The gastrointestinal tract plays a pivotal role in the pathogenesis of acute critical illness and may affect its outcomes.

  • Enteral nutrition is preferred to parenteral nutrition in critically ill patients in the absence of severe shock and gastrointestinal contraindications.

  • Early enteral nutrition (within 24-48 hours) using a feeding protocol with gradual increase of the dose to reach the calorie target within 5-7 days is the preferred feeding strategy for most critically ill patients.

  • Parenteral nutrition is indicated if enteral nutrition is not feasible or does not meet calorie targets by the end of the first week of critical illness.

  • Protein intake is an important element of nutritional support with the current evidence favoring higher doses after the acute phase of critical illness.

  • Immunonutrition should not be used routinely. Supplementation of glutamine is indicated in certain patients (burn and trauma cases).

  • Enteral feeding intolerance commonly complicates enteral nutrition. However, the routine monitoring of gastric residual volume does not prevent aspiration pneumonia and does not affect outcome.


Nutritional support is an essential component of the management of the critically ill. In this chapter, we will review the pathophysiologic changes related to nutrition during critical illness, discuss the different nutritional approaches in the intensive care unit (ICU), and present evidence-based nutritional support in critically ill patients. Table 19-1 includes the definitions of selected terms commonly used in critical care nutrition.

TABLE 19-1Definitions of Selected Terms Often Used in Critical Care Nutritiona

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