Fig. 2

Heart rate variability. Temporal and spectral representation of 6-s-long ECG segment (t = 240 to 270 s) for pig 9 (file 25) showing: a the zero-centered ABP time series (blue in mmHg) with detected R peaks indicated with black circles, the zero-centered inverted ECG time series (red in mV) with detected R-peaks indicated with black circles and the resulting RR-interval time series for peak detection methods. b The Lomb-scale normalized perio-cardiogram derived from the ECG RR-interval time series showing the peak at 0.2 Hz induced by mechanical ventilation set at 15 cycles per minute