Assessment of Patient Positioning

The purpose of this study is to ultimately prevent injuries to nerves during surgical procedures. Living donor liver transplant or hepatectomy (removal of a piece of the liver) patients will receive an arterial line as standard of care. The arterial line helps monitor blood pressure along with the compression of important vessels during surgery. In addition, research participants will undergo neuromuscular monitoring using Somato-Sensory Evoked Potential (SSEP) or Evoked Potential Assessment Device (EPAD). During an operation, neuromuscular monitoring can tell doctors if the nerves being studied are working normally or if they are at risk for injury. This study will help investigators to understand what kind of monitoring is best to prevent nerve injuries during a surgical procedure.