Perioperative liver graft function: the role of oxygen transport and utilization

To assess the evolution of satisfactory neohepatic graft function or failure, hemodynamic variables, along with data for oxygen delivery and utilization, were analyzed retrospectively in 99 patients undergoing orthotopic liver transplantation. Caval cross-clamping without venovenous bypass initiated a series of hemodynamic events, characterized by decreases in pulmonary artery pressures, cardiac output, and arterial pressures and increases in systemic vascular resistance, with reciprocal changes after unclamping. Concerning oxygen transport, the increased oxygen delivery after caval unclamping led to increases of mixed venous oxygen tension, decreases of oxygen extraction, and the arteriovenous oxygen content difference. The most striking result, however, was that with similar values for oxygen delivery, the patients with primary nonfunction (n = 9) had both lower anhepatic oxygen consumption, much smaller increases in oxygen consumption, and lower ratios of oxygen extraction during reperfusion of the liver than the patients with normal initial graft function (n = 90). Thus, distinct increases in total body oxygen consumption were found to be indicative of the onset of hepatocellular function and satisfactory neohepatic graft function. The authors conclude that perioperative measurements of whole-body oxygen consumption are important in reflecting early allograft viability during orthotopic liver transplantation without anhepatic venovenous bypass.