Nutritional support in the critically ill

Major injury evokes a constellation of reproducible hormonal, metabolic, and haemodynamic responses which are collectively termed ‘the adaptive stress response’. The purpose of the adaptive stress response is to facilitate tissue repair and restore normal homeostasis. If critical illness is prolonged, the adaptive stress response may become maladaptive, in essence exerting a parasitic effect leaching away structural proteins and impairing host immunity. Primarily therapy should be directed towards the underlying illness, as nutritional support per se will not reverse the stress response and its sequelae. Nonetheless, adequate nutritional support in the early stages of critical illness may attenuate protein catabolism and its adverse effects. This chapter covers nutritional assessment; detection of malnutrition; energy and protein requirements; monitoring the effectiveness of nutritional replacements; nutritional delivery; complications; and refeeding syndrome