Prediction of Low Frequency Blood Pressure Oscillations via a Combined Heart/Resistance Model

Abstract

Low frequency oscillations in blood pressure (BP) can occur due to a feedback pathway between the sensing of BP and the central nervous system (CNS), often termed the baroreflex, affecting both cardiac output (heart-rate and stroke volume) and peripheral resistance. In this paper, an integrated model of both these subsystems is assembled and an analysis technique developed, which shows the conditions under which a limit cycle oscillation can occur. In particular, the role of mean levels of cardiac output and peripheral resistance, previously thought to be relatively unimportant, in establishing and maintaining sustained oscillations, is highlighted. The ultimate aim of this analysis is to assist in the development of diagnostic tests based on measurement of low-frequency blood pressure oscillations.

A Simple Soft Limiter Describing Function for Biomedical Applications

“…2). The attenuation of these harmonics has been dealt with in Section V-B and previous work in this area [26] has also confirmed that the first harmonic at the nonlinearity output is approximately 30 dB down on the fundamental, corresponding to a reduction factor of 0.03. Therefore, it is reasonable to assume that the single frequency DF is valid in this case.…”

The modulation of neural blood pressure control by blood pressure pulsatility

“…Rather, an alternative approach, based on establishing conditions for sustained propagation around the neural BP control loop is required. [9] However, both approaches (Nyquist and sustained propagation) require a compact representation of the nonlinear baroreflex curves representing the static relationship between BP and sympathetic/parasympathetic nerve activity to the peripheral resistance and heart. This can be achieved via the describing function [8].…”