The patients are at the greatest risk for metabolic complications during the first few weeks of nutritional therapy. Complications related to parenteral nutritional therapy are typically catheter-related, related to metabolic homeostasis or related to changes in the gastrointestinal tractus function. Because the nutrient is delivered directly into a central vein, complications related to the catheter and metabolic homeostasis may be potentially life-threatening. Clinicians who are trained to recognize these complications and initiate appropriate therapy before co-morbid conditions develop.