There are different methods for measuring cardiac output (CO) completely non-invasive, which are used today. Two of these should be used in the study to examine the CO in an older group of patients (> 65 years) undergoing major trauma surgery. The first method is the esCCOTM-technology by Nihon Kohden, the second uses the Volume Clamped Method via a finger-cuff by Nexfin Edwards life sciences. Both technologies work continuously and fully non-invasive.