Norepinephrine in small-for-size liver grafts: an experimental study in pigs

BACKGROUND: Norepinephrine plasma levels may play a role in small-for-size grafts dysfunction at the early posttransplant period. MATERIALS AND METHODS: The 18 pigs used as recipients were assigned to group 1 (n = 6), group 2 (n = 6), and group 3 (n = 6) and given grafts with graft-to-recipient volume ratios of 1:1, 2:3, and 1:3, respectively. Blood serum norepinephrine was measured by high-performance liquid chromatography with electrochemical detection at the following time points: pre-anhepatic period (baseline); anhepatic period; and 30, 60, 180, and 360 min after reperfusion. Graft arterial and portal vein flows were obtained 30, 60, 180, and 360 min after reperfusion by the aid of an ultrasonic flowmeter. Aspartate transferase (AST) and international normalized ratio (INR) were measured before the procedure (baseline), and at 180 and 360 min after reperfusion. RESULTS: Anhepatic phase was characterized by a significant increase (6- to 8-fold) of norepinephrine in all groups (P < 0.05). In groups 1 and 2 plasma norepinephrine returned to normal values 30 min after reperfusion. In group 3, plasma norepinephrine remained significantly increased at every time point of the study compared to groups 1 and 2 (P < 0.001). Hepatic artery and portal vein flows in group 3 were significantly (P < 0.05) reduced and increased, respectively, compared to groups 1 and 2 at all times measured. Liver function tests (AST and INR) 360 min after reperfusion were significantly higher in group 3 compared to groups 1 and 2. CONCLUSIONS: Norepinephrine levels are increased in very small-for-size grafts and this increase may be associated with early graft dysfunction.