Veno-venous bypass in experimental liver transplantation: portal-jugular versus caval-portal-jugular.

This study was undertaken to compare the changes in physiologic variables caused by the use of two different types of pump-assisted veno-venous bypass during experimental liver transplantation. The experiments, performed on female pigs weighing 30 +/- 2 kg, were divided into two groups depending on the bypass used. During the anhepatic phase a pump-assisted portal-jugular (PJ) bypass was used in Group 1 (n = 8) at a flow rate of 15 ml kg-1-min-1, while a pump-assisted caval-portal-jugular (CPJ) bypass was used in Group 2 (n = 8) at a flow rate of 20 ml kg-1-min-1. Intraoperative haemodynamics, pulmonary gas exchange, haematological and serum biochemical parameters were evaluated. Postoperative animal survival rate and complications associated with the bypass used were evaluated. Mean pulmonary artery pressure (Ppa) and pulmonary vascular resistance (Pvr) showed significantly different behaviour in the two groups, whereas the remaining parameters all showed the same trend. Thus an earlier and more substantial increase in Ppa and Pvr values was found in Group 1 when compared to Group 2 during the anhepatic phase. The different behaviour shown by Group 1 may depend on the release of circulating vasoactive substances generated following pelvic venous congestion caused by the temporary clamping of the inferior vena cava. In conclusion, this study indicates that the pump-assisted CPJ bypass is more suitable than the pump-assisted PJ bypass. Furthermore, in order to obtain better results it should be used routinely in porcine liver transplantation.