Changes of Oxygen Saturation in Inferior Vena Cava (IVC) in Patients During and After High Risk Abdominal Surgery and Relationship to the Outcome

Tissue hypoxia is one of the most important factors leading to the development of multiorgan failure. Patients presenting for emergent major abdominal surgery might suffer from organ hypoperfusion. Thus, early detection of the imbalance between oxygen supply and demand may improve the outcome. The investigators believe that hypoperfusion of the abdominal organs will cause a decrease of the saturation in the hepatic vein and in the IVC.