Recurrence plot analysis of the coupling between respiration and cardiovascular variability signals

The authors performed a quantitative study of sub-harmonic synchronization and entrainment phenomena between respiration and short-term Heart Rate and Blood Pressure variability signals by the Recurrence Plot Analysis (RPA). Quantification of the recurrence plots has been obtained using descriptors such as Percent Recurrence, Percent Determinism and Entropy of Recurrences. The authors applied RPA to data obtained in control breathing at different frequencies from 10 normal subjects. The breathing frequencies were chosen to elicit interference phenomena between LF and HF frequency components. Unlike the power spectral estimation, RPA seems to be succeeds in detecting entrainment and transient phase locking phenomena; moreover, the recurrence descriptors turn out to be particularly suited for a quantitative evaluation of the different phenomena observed.