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Nutrition support in critically ill patients: An overview

David Seres, MD
Section Editors
Polly E Parsons, MD
Timothy O Lipman, MD
Deputy Editor
Geraldine Finlay, MD


Nutrition support refers to enteral or parenteral provision of calories, protein, electrolytes, vitamins, minerals, trace elements, and fluids. The fundamentals of nutrition support for critically ill patients will be reviewed here, including the goals, outcomes, indications, contraindications, and daily nutritional requirements. Access, formulations, prescribing, monitoring, and complications of enteral and parenteral nutrition are discussed separately. (See "Nutrition support in critically ill patients: Enteral nutrition" and "Nutrition support in critically ill patients: Parenteral nutrition".)


Nutritional needs in the critically ill are poorly understood and vary with the phase of critical illness. Although outcomes have not been adequately studied in randomized trials, the primary goal of nutrition support is to alter the course and outcome of the critical illness. Major goals are determined by the following principles:

Acute critical illness is traditionally thought to be characterized by catabolism exceeding anabolism [1-3]. However, with better management of ventilatory failure, fever, anxiety, and pain, calorie consumption, as measured by calorimetry, has been dramatically reduced [4].  

Carbohydrates are believed to be the preferred energy source during this period because fat mobilization is impaired [5].

The basis of protein prescriptions is the hope for mitigation of the breakdown of muscle proteins into amino acids, which then serve as the substrate for gluconeogenesis, as reflected in a favorable nitrogen balance [6]. This remains theoretical, as the results of studies have been contradictory. While supplementary protein is still recommended for critically ill patients, there is growing concern that overprescription of protein may have detrimental impact on outcomes overall [7-9].


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Literature review current through: Sep 2016. | This topic last updated: Sep 1, 2016.
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