Body Composition Monitoring(BCM) for Determination of the Fluid Status in Patients Undergoing General Anesthesia

The purpose of this study is to evaluate a recently developed device, which measures body composition (i.e. the water content of the body) in the perioperative setting. Specifically the investigators will test the hypothesis, that extracellular water content after surgery correlates to the amount of intraoperative infusion and positive fluid balance. Furthermore the investigators will test, if preoperative evaluation of body water helps to determine intraoperative fluid requirements and to guide fluid administration.