The evaluation of sBRR sequence random occurrences: A model for surrogate data

The real-time monitoring and analysis of cardiovascular oscillations are used in everyday clinical practice. Their analyses could uncover the mutual interactions of the key variables: RR intervals, and systolic blood pressure (SBP). The sequence method is used for the analysis of the baroreflex RR-SBP relationship in order to estimate the gain of the baroreflex (BRR) feedback loop. The model proposed serves as an auxiliary tool for the sequence method technique in the domain of isodistributional (ID) surrogate data testing. The model is in the form of a finite, ergodic Markov chain delivering the formulae for the temporal sequence parameters (distribution, length, and number of sequences) in ID surrogate data. The analytical tool provided measures the degree of randomness in sequences estimated from the original RR-SBP time series.