Under-estimation of baroreflex sensitivity through a closed loop model due to non-Gaussian property of blood pressure distribution

Non-invasive estimation of baroreflex sensitivity (BRS) is one of the major targets of cardiovascular dynamics analyses including the sequence method and closed loop modeling. However, the closed loop model is known to under-estimate BRS in comparison with that by the sequence method and the vasoactive agent injection. In this paper, BRSs for sleep-waking states are estimated by applying the sequence method to the multivariate time series measured from the actual cardiovascular system. The same estimation is performed to the time series generated by the multivariate autoregressive (MAR) model driven by the innovation process. The result shows the MAR model-based method under-estimates BRS in comparison with that for the actual data. It is suggested that the under-estimation is attributed to the non-Gaussian property of blood pressure distribution.