Fig. 4
Receiver operating characteristic (ROC) curves during head-up tilt with the four different respiratory resistors. a: Pulse pressure variation (PPV) with area under the ROC curve 0.83 (0.61;1.00) (confidence interval) for no resistor, 0.73 (0.42;1.00) for the inspiratory resistor, 0.73 (0.40;1.00) for the expiratory resistor, and 0.59 (0.25;0.93) for the combined inspiratory and expiratory resistor. b: Stroke volume variation (SVV) with area under the ROC curve 0.73 (0.46;1.00) for no resistor, 0.75 (0.46;1.00) for the inspiratory resistor, 0.82 (0.58;1.00) for the expiratory resistor, and 0.58 (0.28;0.88) for the combined inspiratory and expiratory resistor. c: Central venous oxygen saturation (ScvO2) with area under the ROC curve 0.67 (0.29;1.00) for no resistor, 0.42 (0.00;0.88) for the inspiratory resistor, 0.46 (0.02;0.90) for the expiratory resistor, and 0.50 (0.08;0.92) for the combined inspiratory and expiratory resistor. d: Systolic blood pressure with area under the ROC curve 0.70 (0.37;1.00) for no resistor, 0.75 (0.46;1.00) for the inspiratory resistor, 0.68 (0.31;1.00) for the expiratory resistor, and 0.67 (0.34;0.99) for the combined inspiratory and expiratory resistor. e: Heart rate (HR) with area under the ROC curve 0.52 (0.08;0.95) for no resistor, 0.53 (0.11;0.96) for the inspiratory resistor, 0.68 (0.29;1.00) for the expiratory resistor, and 0.63 (0.22;1.00) for the combined inspiratory and expiratory resistor. f: Stroke volume (SV) with area under the ROC curve 0.63 (0.22;1.00) for no resistor, 0.70 (0.36;1.00) for the inspiratory resistor, 0.67 (0.25;1.00) for the expiratory resistor, and 0.60 (0.19;1.00) for the combined inspiratory and expiratory resistor