Identification of sources of low frequency variability of arterial blood pressure: cardiac output acts as a buffer and not as a source.

Arterial blood pressure (ABP) short term variability is due to beat-by-beat fluctuations in cardiac output (CO) and total peripheral resistance (TPR), which have distinct effects at low and high frequencies. In particular, it was shown that CO is able to buffer TPR slow oscillations in the LF band, but it has not been addressed if CO can contribute to oscillations of ABP in this band. In this paper, we propose a model for the identification of ABP variability sources, in order to show evidence that CO fluctuations are not a source of ABP LF oscillations, but they only buffer ABP variability of vasomotor origin.