Assessing Fluid Responsiveness With PWTT

Pulse wave Transit time (PWTT) is a parameter calculated from ECG and pulseoximeter. It is supposed to help assessing the preload Status and guide intraoperative fluid therapy. This Project aims to validate the benefit of PWTT assessment in an observational clinical fluid study. In case of hypovolemia, patients will receive a fluid Bolus and hemodynamic data from clinical Standard Monitoring, esophageal doppler and PWTT will be recorded before and after the fluid Bolus. Receiver operating characteristic (ROC) curve will be used to determine the validity of PWTT as indicator for fluid responsiveness and its cut off value.