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

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.

Inclusion Criteria:

• patients undergoing orthopedic surgery with need for invasive blood pressure measurements
• age ≥ 18 years
• signed informed consent
• no participation on another interventional study

Exclusion Criteria:

• refusal of participation
• patients who are not able to sign informed consent
• atrial fibrillation with arrhythmia
• peripheral arterial disease > Fontain IIa
• scleroderma
• presence of an arterio-venous shunt on upper limb
• contraindication for femoral arterial vascular access
• contraindication for transesophageal echocardiography
• stage III heart valve defects
• shunt heart defects
• solitary regional anaesthesia
• pregnant or breastfeeding women