Nutrition is an important aspect of patient care in acute or chronic critical illness. Appropriate nutritional support during the acute phase of critical illness has the potential to reverse or mitigate adverse consequences of poor nutritional status. The nutritional status of a chronically critically ill patient depends on the nutritional therapy given during acute critical illness. The primary function of the nutritional assessment is to identify pre-existing malnutrition in order to prevent or minimize further loss of body weight, particularly of cell mass, composition and function (Lombardo et al.,2005)

Although TPN remains an important route of nutrient delivery in critically ill patients unable to tolerate EN, recent data suggest the importance of EN in patients with a functioning gastrointestinal tract. EN restores intestinal integrity and preserves the barrier function of the gut. It also reduces the incidence of gastrointestinal bleeding. Early enteral feeding can enhance gut motility by minimizing the delay in gastric emptying (Peter et al.,2005).

Multiple complications are associated with nutritional support. Some are related to both TPN and EN like nutritionally associated hypercapnia, some are related to EN only like dirarrhea and abdominal distention and some are related to TPN only like catheter complications as pneumthorax and metabolic complications like hyperglycemia and vitamin deficiencies (Peter et al.,2005).