ILEAL NUTRITIONAL FUNCTION AFTER ONE-STAGE ORTHOTOPIC ILEUM TRANSPLANTATION IN THE GROWING PIG - REVERSAL OF LETHAL SHORT-BOWEL SYNDROME

Intestinal isolation is associated with hypoplasia of defunctioned muc osa and reduction in the segmental absorption, whereas the presence of luminal nutrition is essential for the expression of the ileal adapti ve response after proximal small bowel resection. On the other hand, i ntensive postoperative graft monitoring is obligatory because of the d isastrous consequences of small bowel graft rejection. Thus, the autho rs sought to develop an experimental ileum transplantation model that provided immediate graft placement in bowel continuity, together with readily available graft monitoring connection through a proximal Roux- en-Y enterostomy. Four groups of pigs were prepared: RESTX (n = 9), pr oximal 50% small bowel resection with simultaneous orthotopic ileum au totransplantation; RES (n = 7), proximal 50% small bower resection; NO NRES (n = 6), transection; and SB (n = 5), short bowel. Early (1 to 4 weeks) and long-term (5 to 12 weeks) studies of animal growth, nutriti onal status, disaccharide absorption, water and electrolyte balances, and liver function were performed after ileum autotransplantation (IAT ) in relation to small intestine of variable length with undivided mes entery (intact neural and lymphatic connections). The perioperative tr ansplantation mortality rate remained at about 10%. Reasons not relate d to the transplantation procedure accounted for the late complication rate of 38%. In the ileum autotransplantation (RESTX) group, weight g ain was recovered 2 to 3 weeks after transplantation, and the mean wei ght reached the preoperative level at 5 weeks. The SB pigs underwent p rogressive weight loss. The transection (NONRES) and proximal resectio n (RES) animals gained weight at similar rates. IAT had no effect on t he plasma protein concentrations. Proximal resection, with or without IAT, was associated with depressed plasma cholesterol contents in the early period. Plasma cholesterol levels amended long-term, after both IAT and proximal resection. IAT resulted in deficient intraluminal pro cessing of maltose, whereas isolated proximal resection tended to enha nce disaccharide absorption early after the surgery. The short bowel p igs were not able to preserve sufficient nutritional status, and demon strated a marked decline in the hemoglobin, protein, and cholesterol l evels. No biochemical signs suggestive of potential liver damage cause d by portocaval graft vascularization were recognized. These findings suggest that one-stage ileum autotransplantation provides sufficient a bsorptive capacity to reverse otherwise lethal short bowel syndrome in the growing pig. However, transplantation disturbs the in vivo absorp tive function of the nonrejecting ileum. Long-term impairment in disac charide absorption may be partially related to an altered intestinal a daptive response secondary to proximal resection when combined with si multaneous transplantation. The authors developed this ileal small bow er transplantation model using rapidly growing pigs, wherein body weig ht gain represents an objective parameter of intestinal absorptive fun ction. Only this type of animal model can yield clinically relevant da ta in the evaluation of a transplant's ability to provide sufficient n utritional function in a growing recipient. (C) 1996 by W.B. Saunders Company