Severe undernutrition

Abstract

Undernutrition in critically ill patients appears to be common, being encountered both at the time of admission and developing during the ICU stay. While many defi nition criteria for this state are available, loss of muscle mass and strength seem to be the most relevant signs. During the ICU stay, the main reason for undernutrition is underfeeding, a frequent occurrence in ICU practice, together with bed rest. Negative energy and nitrogen balance may result in an increase in morbidity and a prolonged rehabilitation period. While nutritional support is essential for these patients, it is important not to induce the refeeding syndrome. Enteral feeding is the preferred route for providing nutritional support but is not always achievable, usually the result of prolonged feeding interruptions. The calorie target should be reached progressively using the gastrointestinal route or the parenteral route if necessary. Indirect calorimetry remains the best guide for appropriately prescribing nutritional support. Protein administration should follow current guidelines. Careful monitoring of electrolytes (mainly phosphorus, magnesium, and potassium) is mandatory. Nutritional support is of extreme importance not only to provide enough nutrients in a defi ciency condition but also to prevent prolonged rehabilitation periods for survivors.