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Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices

Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices
Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices

Background: Dynamic cerebral autoregulation, that is the transient response of cerebral blood flow to changes in arterial blood pressure, is currently assessed using a variety of different time series methods and data collection protocols. In the continuing absence of a gold standard for the study of cerebral autoregulation it is unclear to what extent does the assessment depend on the choice of a computational method and protocol.

Methods: We use continuous measurements of blood pressure and cerebral blood flow velocity in the middle cerebral artery from the cohorts of 18 normotensive subjects performing sit-to-stand manoeuvre. We estimate cerebral autoregulation using a wide variety of black-box approaches (ARI, Mx, Sx, Dx, FIR and ARX) and compare them in the context of reproducibility and variability.

Results: For all autoregulation indices, considered here, the ICC was greater during the standing protocol, however, it was significantly greater (Fisher’s Z-test) for Mx (p < 0.03), Sx (p < 0.003) and Dx (p < 0.03).

Conclusions: In the specific case of the sit-to-stand manoeuvre, measurements taken immediately after standing up greatly improve the reproducibility of the autoregulation coefficients. This is generally coupled with an increase of the within-group spread of the estimates.

1350-4533
Mahdi, Adam
01b21495-81ce-4207-a565-2ec344bf4b44
Nikolic, Dragana
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Birch, Anthony A.
0a31c6be-d058-4ca4-a332-8dcff4a470ab
Olufsen, Mark
d03ad074-3857-40d1-b22e-b7b1fcd8fe9e
Panerai, Ronney B.
7acaf714-a17c-4df2-a1f3-b148c1445517
Simpson, David M.
53674880-f381-4cc9-8505-6a97eeac3c2a
Payne, Stephen J.
457f9441-a08f-4396-bd63-1bba56b90d9a
Mahdi, Adam
01b21495-81ce-4207-a565-2ec344bf4b44
Nikolic, Dragana
772b3eb2-c994-440a-ab86-27e862bd39f7
Birch, Anthony A.
0a31c6be-d058-4ca4-a332-8dcff4a470ab
Olufsen, Mark
d03ad074-3857-40d1-b22e-b7b1fcd8fe9e
Panerai, Ronney B.
7acaf714-a17c-4df2-a1f3-b148c1445517
Simpson, David M.
53674880-f381-4cc9-8505-6a97eeac3c2a
Payne, Stephen J.
457f9441-a08f-4396-bd63-1bba56b90d9a

Mahdi, Adam, Nikolic, Dragana, Birch, Anthony A., Olufsen, Mark, Panerai, Ronney B., Simpson, David M. and Payne, Stephen J. (2017) Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices. Medical Engineering & Physics. (doi:10.1016/j.medengphy.2017.06.006).

Record type: Article

Abstract

Background: Dynamic cerebral autoregulation, that is the transient response of cerebral blood flow to changes in arterial blood pressure, is currently assessed using a variety of different time series methods and data collection protocols. In the continuing absence of a gold standard for the study of cerebral autoregulation it is unclear to what extent does the assessment depend on the choice of a computational method and protocol.

Methods: We use continuous measurements of blood pressure and cerebral blood flow velocity in the middle cerebral artery from the cohorts of 18 normotensive subjects performing sit-to-stand manoeuvre. We estimate cerebral autoregulation using a wide variety of black-box approaches (ARI, Mx, Sx, Dx, FIR and ARX) and compare them in the context of reproducibility and variability.

Results: For all autoregulation indices, considered here, the ICC was greater during the standing protocol, however, it was significantly greater (Fisher’s Z-test) for Mx (p < 0.03), Sx (p < 0.003) and Dx (p < 0.03).

Conclusions: In the specific case of the sit-to-stand manoeuvre, measurements taken immediately after standing up greatly improve the reproducibility of the autoregulation coefficients. This is generally coupled with an increase of the within-group spread of the estimates.

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1705.04942 - Accepted Manuscript
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Accepted/In Press date: 1 June 2017
e-pub ahead of print date: 8 July 2017

Identifiers

Local EPrints ID: 412657
URI: http://eprints.soton.ac.uk/id/eprint/412657
ISSN: 1350-4533
PURE UUID: 88eebe7a-fd21-46da-9c28-430c72280e20

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Date deposited: 24 Jul 2017 16:33
Last modified: 07 Oct 2020 06:25

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