Fig. 3. Systolic blood pressure variations (SPV) and their components, dUp and dDown, pulse pressure variation (PPV) of arterial blood pressure, plethysmographic waveform variation (PWV), and pulse oximetry plethysmographic waveform variation (dPOP) during all stages of blood withdrawal. The data are presented as mean ± SD. * Significant compared with baseline (BL) (P < 0.005). ECBV = estimated circulating blood volume.