ABSTRACT
The metabolic response to critical illness is characterized by hypermetabolism, hyperglycemia, increased lipolysis, and net protein catabolism [1]. Skeletal muscle is broken down, and the amino acids are used for gluconeogenesis and protein synthesis. Reprioritization of hepatic protein synthesis occurs resulting in synthesis of positive acute phase proteins (e.g., C-reactive protein) and decreased synthesis of negative acute phase proteins (e.g., prealbumin, albumin) [2]. Additionally, bed rest and suboptimal nutrient intake contribute to depletion of lean body mass (see Chapter 1). Nutritional support in the critically ill should occur early, be tailored to the patient’s medical condition, nutritional status, and available route of administration; provide nutrients compatible with current metabolism while avoiding complications; and improve patient outcomes [3]. This chapter reviews the suggested macronutrient (carbohydrates, protein, and lipids) composition of nutritional support provided to critically ill patients.
