The continuous hemodynamic monitoring of patients during surgery has recently changed from invasive and semi-invasive methods to completely non-invasive technologies. The accuracy and precision of this way of measuring cardiovascular parameters in comparison to the invasive standard is still controversial. Especially for older patient with atherosclerotic alteration of the blood vessels the utility of non-invasive monitoring systems is not shown yet. But principally this group with a high level of comorbidity might profit notably from less invasive procedures. This is the reason for the planed research.