Practicalities of nutrition support in the intensive care unit

Nutrition support improves clinical outcomes in the critically ill and our understanding of its effects has advanced significantly over the last few years. Three recently published evidence-based guidelines have made generally consistent and thorough recommendations to assist clinicians in providing nutrition support. This review will focus on various aspects of these recommendations, concentrating on the practicalities of nutrition support in the intensive care unit, such as its optimal mode and composition.

Enteral nutrition is preferred to parenteral nutrition unless there is a major gut condition which will delay commencement of enteral nutrition. Nasogastric feeding should begin within 24 h, but if intolerance develops, small bowel feeding or pro-motility drugs (erythromycin or metoclopramide) should be attempted before resorting to supplementary parenteral nutrition. Enteral nutrition should not routinely be supplemented with arginine or glutamine, but it should contain a package of eicosapentaenoic acid, gamma-linolenic acid and antioxidants if the patient has acute lung injury or sepsis. Parenteral nutrition should be glutamine supplemented and the prescription should be limited in energy to avoid hyperglycemia. Whether using enteral nutrition or parenteral nutrition, most patients should receive intravenous selenium, and may also need zinc and copper supplementation.

Intensive care unit patients should have nutrition support based on recent evidence-based guidelines with a preference for nasogastric feeding. If intolerance occurs, pro-motility drugs and small bowel feeding should be attempted. Clinicians should also consider carefully the composition of the nutrition support regimen with regard to lipid content (especially eicosapentaenoic acid and gamma-linolenic acid), antioxidants, glutamine and other micronutrients.