Intestinal transplantation is indicated in cases of intestinal failure, defined as the irreversible inability of the intestine to adequately sustain the body's nutritional, fluid, and electrolytic balance in the absence of parenteral support. Irreversible intestinal failure can be the result of loss of surface area, functional disturbances, or the presence of unresectable tumors involving the intestine. The etiology of these in turn can be either congenital or acquired. Clinical manifestations include but are not limited to dehydration, deficiencies of nutrients and vitamins, gallstones, stomach hyperacidity, renal stones, hyperoxaluria, skin irritation, and malabsorptive diarrhea. It has been observed that < 20% of adults with < 100 cm of intestine or end jejunostomy will be able to maintain nutritional requirements in the absence of total parenteral nutrition (TPN) (Messing et al, 1999). In the pediatric population, failure to wean from TPN has been found to be associated with absence of enteral feeding tolerance early after birth, around 30 cm or less of small intestine, and absence of enterocolonic continuity (Fishbein et al, 2003; Vargas et al, 1987; Pharaon et al, 1994).
Short gut syndrome (loss of approximately 70% of the native small bowel length) is the most frequently encountered cause of irreversible intestinal failure. Causes of short gut syndrome in children include necrotizing enterocolitis, atresia, and volvulus. In adults, etiologies are trauma, surgical damage, repeated resections for Crohn's disease, mesen-teric vascular injuries, extensive adhesions, and desmoid tumors. Defective motility of the gastrointestinal (GI) tract causing pseudo-obstruction is associated with total agan-glionosis, neuropathy, and myopathy. Impaired absorptive function is found secondary to radiation injury, autoimmune processes, extensive polyposis, and microvillus inclusion disease (Sturm et al, 1997; Thompson, 1994; Granata and Puri, 1997; Herzog et al, 1996).
As previously mentioned, intestinal transplantation should be undertaken in those cases in which there is a life threatening complication associated with TPN treatment. Ten to 40% of patients with intestinal failure die as a result of these complications within 3 to 5 years. Such complications include cholestatic liver failure, venous thrombosis leading to loss of access, and severe line sepsis. Isolated small intestinal transplantation is also considered in cases where TPN has led to reversible liver injury (Grosfeld et al, 1986). Liver and small bowel grafts are considered in cases of irreversible liver failure. Multivisceral transplantation is undertaken in instances when individual patient characteristics have led to the loss or malfunction of the viscera being replaced (Kato et al, 2002).
Medicare-approved criteria for failure of parenteral nutrition include "impending or overt failure due to TPN-induced liver injury, thrombosis of 2 or more central veins, the development of 2 or more episodes of systemic sepsis secondary to line infection per year that require hospitalization, a single episode of line-related fungemia, septic shock, and/or acute respiratory distress, frequent episodes of severe dehydration despite intravenous fluid supplementation in addition to TPN." (Fishbein et al, 2003)
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