In high risc patients undergoing orthopedic surgery an extended cardiopulmonary observation improves patients safety and postoperative outcome. Therefore invasive procedures as Picco2-system, FloTrac and transesophageal echocardiography (tee) have the advantage to measure or calculate stroke volume. Disadvantage of this treatments is the need for a vascular access with all its complications.~In this study the stroke volume measured by a new noninvasive finger cuff system (NexFin) should be validated in comparison to invasive hemodynamic monitoring systems as Picco2-system, FloTrac and tee.
Main hypothesis: there is no difference between stroke volume measurements recorded by a new noninvasive finger cuff system (NexFin) and invasive hemodynamic monitoring systems as Picco2-system, FloTrac and transesophageal echocardiography