The planned study is the comparison of 3 different hemodynamic monitoring procedures. For the evaluation the investigators use the method described by Bland and Altmann for calculating the mean deviation (bias) and the precision (mean value ± 2 standard deviations. In the case of multiple measurements , the modification of the Bland-Altman method is applied (repeated measurements). The number of cases was determined with n = 60 patients, followed by an intermediate evaluation. For a Bland-Altman analysis, the width w of the confidence interval for the Limits of Agreement is calculated as w = 6.79 • σ • 1 / √n, where n is number of cases and σ is the standard deviation. For a case count of n = 60, the result is w = 0.88 • σ and thus for this explorative study a sufficiently large number. In case of the dynamic variables, the percentage matching and the calculation of the kappa index are also used for the statistical evaluation.