Fluid therapy before and under surgery can be guided by measurement of the hearts ability to eject blood (cardiac output). By doing this it has been shown that the occurrence of nausea,vomiting and complications generally can be reduced. The function of the heart has been measured with a probe in the esophagus in in earlier studies. We want to correlate these results with other techniques by which fluid therapy also is guided in daily practice. These are: SVO2, modelflow (finapres)and NIRS. These methods are noninvasive except SVO2 measurement which requires a central venous catheter (CVK). Therefore we have chosen a population in which CVK is standard in our institution. We thereby don´t apply any further risks than daily practice and the project is considered as a quality assessment of used standards.