Sample Size Calculation A pilot study of 20 patients revealed a detected area under the ROC curve (AUC) of 0,91 for dIVCmax/IVCCI and for dIVCmax 0,82 with rank correlation between the two assays being 0.87 in both positive and negative cases. Based on this result, a sample of 56 patients will achieve 80% power to detect significant difference (at a level 0.05) between dIVCmax/IVCCI and dIVCmax.