Impact of Functional Hepatic Venous Outflow Obstruction on Perioperative Outcome After Living-Donor Liver Transplant

Abstract

An optimal initial graft function after living-donor liver transplant depends on optimal graft hemodynamics. Nonmechanical impediments to free hepatic venous outflow, due to elevated central venous pressure, may obstruct the "functional" hepatic venous outflow. Here, we evaluated whether central venous pressure affected early graft function and outcomes in adult living-donor liver transplant recipients. This prospective observational study included 61 living-donor liver transplant recipients without technical complications who received transplants from August 2013 to November 2014. Hemodynamic variables were measured preoperatively, at anhepatic phase, 30 minutes postreperfusion, at end of surgery, and during postoperative days 1-5. Patients with high central venous pressure showed functional hepatic venous outflow obstruction, which caused delayed recovery of graft function. Although postoperative central venous pressure was the only identified independent risk factor for mortality, all 5 deaths in our study group occurred in those who had high central venous pressure at the anhepatic, postreperfusion, end of surgery, and postoperative phases. A postoperative central venous pressure value of ~11 mm Hg was determined to be the cutoff for high-risk mortality, with area under the curve of 0.859 (sensitivity of 80%, specificity of 68%). Increased central venous pressure was associated with increased portal venous pressure (increase of 45%, range, 28%-89%; P = .001). Central venous pressure at end of surgery (r = 0.45, P ≤ .001) and at posttransplant time points (r = 0.29, P = .02) correlated well with portal venous pressure at end of surgery. Other risk factors for early allograft dysfunction were Model for End-Stage Liver Disease and cardiac output posttransplant. High central venous pressure, modulating portal venous pressure, can result in functional hepatic venous outflow obstruction, causing delayed graft function recovery and increased risk of mortality. Maintaining a central venous pressure below 11 mm Hg is beneficial.