Ammonia elimination as a rapid index of viability in liver grafts in dogs

We examined intraoperative changes in blood ammonia levels and the correlation with graft viability in orthotopic liver transplantation (OLTx) in 29 dogs. Blood ammonia levels following total hepatectomy were examined using five dogs. These levels immediately following hepatectomy (15 min) were significantly higher (212 +/- 29 micrograms/dl) over values noted before hepatectomy (93 +/- 11 micrograms/dl, P less than 0.05). OLTx was performed using the cuff technique. The animals were divided into two groups: Group A (n = 6 pairs), OLTx with a nonpreserved fresh graft; Group B (n = 6 pairs), OLTx with an 8-hr preserved graft with lactated Ringer (4 degrees C). In both groups, the blood ammonia levels before the surgery and at the anhepatic phase data did not differ; however, following reperfusion, the levels in Group B were significantly higher (211 +/- 26 at 15 min, 200 +/- 50 micrograms/dl at 30 min) than those in Group A (121 +/- 10 at 15 min; P less than 0.01, 109 +/- 9 micrograms/dl at 30 min; P less than 0.05). The blood ammonia level highly correlated with adenosine triphosphate contents in the liver tissue, blood level of lactic acid, and amount of bile output, all pertinent indicators of the graft viability. Thus, the potential to eliminate ammonia immediately after reperfusion can serve as an indicator of graft viability. The intraoperative monitoring of blood ammonia levels can be included in management guidelines in cases of liver transplantation.