Effects of a passive venous bypass on cardiovascular and acid-base balance variables during liver transplantations in pigs.

The anhepatic phase of liver transplantation is accompanied by numerous hemodynamic and metabolic sequelae. The effects of a passive venous bypass on cardiovascular and metabolic variables during the anhepatic phase of orthotopic liver grafting was investigated in 15 pigs (group I) and compared with 10 pigs (group II) without a shunt. In a further five pigs (group III), after total vascular exclusion of the liver, an anhepatic state similar to the anhepatic phase of orthotopic liver transplantation was simulated. The resulting cardiovascular effects in group III were measured first without a shunt and afterwards under the conditions of a passive portojugular shunt. During the anhepatic phase, nonshunted animals required 113% more fluid replacement and 122% more sodium bicarbonate, compared to shunted animals, in order to keep pulmonary capillary wedge pressure (PCWP) and pH in the same range. The end-tidal PCO2 decreased twice as much in nonshunted pigs. The MAP dropped from 86 +/- 6 mmHg to 46 +/- 3 mmHg in experiments without a passive venous bypass, compared to a decrease from 88 +/- 5 mmHg to only 69 +/- 4 mmHg when a passive porto-jugular shunt was used. Concomitantly, a compensatory increase of HR, SVR, and PVR was observed, more pronounced in the nonshunted group. Although the survival after experimental orthotopic liver transplantation was identical in both groups, a passive venous bypass is of great benefit during the anhepatic phase of liver transplantation as regards the cardiovascular and metabolic variables.