Metabolic effects of systemic venous drainage in small bowel transplantation

Small bowel transplantation has proved feasible in rats and in larger animals, but several important questions remain to be addressed before it becomes routine therapy in humans. One consideration is the site of venous outflow of the allograft. While portal drainage reestablishes the physiologic route of venous outflow, systemic drainage creates a partial mesocaval shunt, the metabolic consequences of which have not been studied in detail. Using a canine model of orthotopic small bowel autotransplantation, we compared the metabolic changes following transplantation with portal versus systemic venous drainage. Changes in blood ammonia levels, plasma amino acid composition, and hepatic blood flow were studied, since the Eck procedure produces metabolic changes of hyperammonemia and amino acid imbalances, while portocaval venous drainage of small bowel transplant produces a profile similar to that in controls. These data suggest that there is no metabolic disadvantage of systemic venous drainage as compared with controls. Because of its technical simplicity, systemic venous drainage may be preferable for small bowel transplantation.