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Dynamic cerebral autoregulation assessment using an ARX model: comparative study using step response and phase shift analysis (in Special Issue on cerebral autoregulation)

Dynamic cerebral autoregulation assessment using an ARX model: comparative study using step response and phase shift analysis (in Special Issue on cerebral autoregulation)
Dynamic cerebral autoregulation assessment using an ARX model: comparative study using step response and phase shift analysis (in Special Issue on cerebral autoregulation)
Middle cerebral arterial blood velocity (MCAv) response to spontaneous and manipulated changes of arterial blood pressure (ABP) was studied in eight subjects using a linear autoregressive with exogenous input (ARX) model. ABP and MCAv were measured non-invasively by photoplethysmograph and transcranial Doppler ultrasound, respectively. Data were recorded at rest (spontaneous changes in ABP) and during thigh cuff (step-wise changes) and lower body negative pressure (sinusoidal changes of 1/12 Hz) tests in both normocapnia and hypercapnia (5% CO2). Since autoregulation is modulated by CO2, respiratory CO2 was simultaneously monitored to allow comparison of cerebral autoregulation status with different CO2 levels. ABP and MCAv were fitted by ARX models and dynamic cerebral autoregulation was estimated by analysing both the step responses and phase shift at the 1/12 Hz of the corresponding ARX models. The ARX model consistently modelled the phase lead of MCAv to ABP and it showed that the phase shift at 1/12 Hz of ARX model is consistent with the real phase shift of the data (p=0.59). Strong linear relationships between pCO2 and gradient of the step response (r=?0.58, p<0.0001) and between pCO2 and phase shift (r=?0.76, p<0.0001) were observed, which suggests that cerebral autoregulation can be assessed by step response or phase shift analysis of the ARX model fitted to ABP and MCAv data with spontaneous changes.
cerebral autoregulation, arx model, linear modelling, cerebral haemodynamics
1350-4533
647-653
Liu, Y.
3f739949-66b7-4396-945b-3e46ae1bd8ba
Birch, A.
a45cb47e-fcf4-4521-b75a-a63e36ebc4da
Allen, R.
956a918f-278c-48ef-8e19-65aa463f199a
Liu, Y.
3f739949-66b7-4396-945b-3e46ae1bd8ba
Birch, A.
a45cb47e-fcf4-4521-b75a-a63e36ebc4da
Allen, R.
956a918f-278c-48ef-8e19-65aa463f199a

Liu, Y., Birch, A. and Allen, R. (2003) Dynamic cerebral autoregulation assessment using an ARX model: comparative study using step response and phase shift analysis (in Special Issue on cerebral autoregulation). Medical Engineering & Physics, 25 (8), 647-653. (doi:10.1016/S1350-4533(03)00015-8).

Record type: Article

Abstract

Middle cerebral arterial blood velocity (MCAv) response to spontaneous and manipulated changes of arterial blood pressure (ABP) was studied in eight subjects using a linear autoregressive with exogenous input (ARX) model. ABP and MCAv were measured non-invasively by photoplethysmograph and transcranial Doppler ultrasound, respectively. Data were recorded at rest (spontaneous changes in ABP) and during thigh cuff (step-wise changes) and lower body negative pressure (sinusoidal changes of 1/12 Hz) tests in both normocapnia and hypercapnia (5% CO2). Since autoregulation is modulated by CO2, respiratory CO2 was simultaneously monitored to allow comparison of cerebral autoregulation status with different CO2 levels. ABP and MCAv were fitted by ARX models and dynamic cerebral autoregulation was estimated by analysing both the step responses and phase shift at the 1/12 Hz of the corresponding ARX models. The ARX model consistently modelled the phase lead of MCAv to ABP and it showed that the phase shift at 1/12 Hz of ARX model is consistent with the real phase shift of the data (p=0.59). Strong linear relationships between pCO2 and gradient of the step response (r=?0.58, p<0.0001) and between pCO2 and phase shift (r=?0.76, p<0.0001) were observed, which suggests that cerebral autoregulation can be assessed by step response or phase shift analysis of the ARX model fitted to ABP and MCAv data with spontaneous changes.

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More information

Published date: 2003
Additional Information: Special issue edited by M. Ursino
Keywords: cerebral autoregulation, arx model, linear modelling, cerebral haemodynamics

Identifiers

Local EPrints ID: 10950
URI: https://eprints.soton.ac.uk/id/eprint/10950
ISSN: 1350-4533
PURE UUID: 2dd5f64f-ad96-4687-96cf-1a655f22a4ca

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Date deposited: 06 May 2005
Last modified: 17 Jul 2017 17:05

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Contributors

Author: Y. Liu
Author: A. Birch
Author: R. Allen

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