Should Low Central Venous Pressure Be Maintained during Liver Transplantation?

Low central venous pressure, which indirectly reflects free hepatic venous pressure, is maintained during hepatic resection surgery to reduce intraoperative blood loss by facilitating hepatic venous outflow. However, whether the low central venous pressure protocol established for non-transplant hepatobiliary surgery should be generalized to liver transplantation is controversial because patients with cirrhosis have decreased portal and hepatic venous blood flow and vulnerability to renal failure. However, consistent with observations from hepatic resection surgeries, lowering central venous pressure during the preanhepatic phase significantly reduces blood loss and transfusion volume. Conversely, inherent study limitations and different study designs have yielded different results in terms of renal dysfunction. Although hepatic venous outflow promoted by lowering blood volume seems to facilitate a liver graft to accommodate portal blood flow increased by portal hypertension-induced splanchnic vasodilatation, the association between low central venous pressure and reduced incidence of portal hyperperfusion injury has not been demonstrated. Stroke volume variation predicts fluid responsiveness better than central venous pressure, but it has not been associated with a greater clinical benefit than central venous pressure to date. Therefore, the safety of maintaining low central venous pressure during liver transplantation has not been verified, and further randomized controlled studies are warranted to establish a fluid management protocol for each phase of liver transplantation to reduce intraoperative blood loss and transfusion rate, thereby maintaining liver graft viability. In conclusion, low central venous pressure reduces intraoperative blood loss but does not guarantee renoprotection or graft protection.