Superior Vena Cava and Its Relationship to Central Venous Pressure Measurements in Liver Transplantation

Central venous pressure (CVP) measured invasively through a central venous catheter in the internal jugular vein or through a right atrial port of a pulmonary artery catheter is commonly used during liver transplant surgery. CVP measurements at the SVC-RA junction are a function of circulating blood volume, right ventricle function, intrathoracic pressure. CVP measurements can also be affected by the presence of tricuspid regurgitation. Because central venous pressure measurements are determined by several factors and do not predict the response to subsequent fluid bolus administration, they are considered "static measures" and are poor indicators of fluid responsiveness. Given the entirely intrathoracic location of the superior vena cava (SVC), its diameter and collapsibility with positive pressure ventilation it is a potentially attractive method of non-invasively estimating CVP. SVC diameter and collapsibility index, dynamic measures of fluid responsiveness have been successfully utilized as echocardiographic indices for fluid responsiveness in ventilated septic patients. Whether SVC collapsibility is correlated with CVP measurements in liver transplant patients is not known. Consecutive patients undergoing liver transplant surgery will be included in the study. Before surgical incision, during the preanhepatic phase, during the anhepatic phase, during the postanhepatic phase and following closure of the deep fascial layer of the anterior abdominal wall simultaneous measurement of SVC diameter, SBC collapsibility index and CVP will be recorded.