Figure 6:An illustration of beat-to-beat cardiac interval extracting from the IMF2 of ABP signal and relationship with respiration. (a) the original IMF2 of ABP signal, (b) the peak detection of R-wave in ECG (solid line) and that of first order difference of IMF2 (dotted line), (c) the RR intervals series in ECG (solid line) and the beat-to-beat time interval series from IMF2 (dotted line), and (d) the EtCO2 concentration.