Fig. 2

Inter-observer reproducibility of Perfused Boundary Region (PBR) measured by the nurses and physician. Eight trained nurses and a physician obtained paired sets of measurements (random order) in a total of 40 patients (n = 25 in the ER and n = 15 in the ICU) to determine the inter-observer reproducibility. a Boxplots showing PBR values (in μm) obtained by the nurses and the physician. The Wilcoxon signed-rank test was used to compare the paired PBR values. b Bland-Altman plot showing the limits of agreement (bias ±1.96 SD) between paired values for the nurses’ and physician’s perfused boundary region (PBR) measurements. (ER: Emergency Department, ICU: Intensive Care Unit, PBR: perfused boundary region, RBC: red blood cell