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Coherent averaging of pseudorandom binary stimuli: Is the dynamic cerebral autoregulatory response symmetrical?

Coherent averaging of pseudorandom binary stimuli: Is the dynamic cerebral autoregulatory response symmetrical?
Coherent averaging of pseudorandom binary stimuli: Is the dynamic cerebral autoregulatory response symmetrical?
Cerebral autoregulation acts to buffer changes in cerebral perfusion pressure. Previous studies have demonstrated that autoregulatory responses display hemispheric symmetry, which may be altered in stroke and traumatic brain injury. There is a paucity of data however on whether the response is symmetrical between those disturbances that cause cerebral hyperperfusion, to those that cause hypoperfusion. Using a previously described assessment method, we employed coherent averaging of the cerebral blood flow velocity (CBFV) responses to thigh cuff inflation and deflation, as driven by pseudorandom binary sequences, whilst simultaneously altering the inspired CO2. The symmetry of the autoregulatory response was assessed with regards to two parameters, its speed and gain. Using the first harmonic method, critical closing pressure (CrCP) and resistance area product (RAP) were estimated, and the gain of the autoregulatory response was calculated by performing linear regression between arterial blood pressure (ABP) and CBFV, ABP and CrCP, and finally ABP and RAP. A two-way repeated measures ANOVA was used to assess the effect of the direction of change in ABP and the method of CO2 administration. Our results suggest that whilst the direction of ABP does not have a significant effect, the effect of CO2 administration method is highly significant (p<10-4). We conclude that the autoregulatory response is symmetric, and that coherent averaging can be combined effectively with our novel assessment method to elucidate the role of CrCP and RAP in the autoregulatory response.
0967-3334
2164-2175
Katsogridakis, Emmanuel
863d80d0-d656-453d-98fe-70f2c16aaaf9
Simpson, David
53674880-f381-4cc9-8505-6a97eeac3c2a
Blush, Glen
817b64e2-5cef-4d22-a105-4068cc9fced3
Fan, Lingke
16854f7b-b107-49cf-a797-e20ab1406fb6
Birch, Anthony
fb23c1a0-9d33-420e-bc59-bce64f8098e5
Allen, Robert
5f90c63a-6431-4cea-8170-03c2f3a6bcc3
Potter, John
c91f5ee4-6d3f-44d5-8de8-70cee505aa3c
Panerai, Ronney
49fb6b54-c188-42be-8204-7de39e95bed1
Katsogridakis, Emmanuel
863d80d0-d656-453d-98fe-70f2c16aaaf9
Simpson, David
53674880-f381-4cc9-8505-6a97eeac3c2a
Blush, Glen
817b64e2-5cef-4d22-a105-4068cc9fced3
Fan, Lingke
16854f7b-b107-49cf-a797-e20ab1406fb6
Birch, Anthony
fb23c1a0-9d33-420e-bc59-bce64f8098e5
Allen, Robert
5f90c63a-6431-4cea-8170-03c2f3a6bcc3
Potter, John
c91f5ee4-6d3f-44d5-8de8-70cee505aa3c
Panerai, Ronney
49fb6b54-c188-42be-8204-7de39e95bed1

Katsogridakis, Emmanuel, Simpson, David, Blush, Glen, Fan, Lingke, Birch, Anthony, Allen, Robert, Potter, John and Panerai, Ronney (2017) Coherent averaging of pseudorandom binary stimuli: Is the dynamic cerebral autoregulatory response symmetrical? Physiological Measurement, 38 (12), 2164-2175. (doi:10.1088/1361-6579/aa9086).

Record type: Article

Abstract

Cerebral autoregulation acts to buffer changes in cerebral perfusion pressure. Previous studies have demonstrated that autoregulatory responses display hemispheric symmetry, which may be altered in stroke and traumatic brain injury. There is a paucity of data however on whether the response is symmetrical between those disturbances that cause cerebral hyperperfusion, to those that cause hypoperfusion. Using a previously described assessment method, we employed coherent averaging of the cerebral blood flow velocity (CBFV) responses to thigh cuff inflation and deflation, as driven by pseudorandom binary sequences, whilst simultaneously altering the inspired CO2. The symmetry of the autoregulatory response was assessed with regards to two parameters, its speed and gain. Using the first harmonic method, critical closing pressure (CrCP) and resistance area product (RAP) were estimated, and the gain of the autoregulatory response was calculated by performing linear regression between arterial blood pressure (ABP) and CBFV, ABP and CrCP, and finally ABP and RAP. A two-way repeated measures ANOVA was used to assess the effect of the direction of change in ABP and the method of CO2 administration. Our results suggest that whilst the direction of ABP does not have a significant effect, the effect of CO2 administration method is highly significant (p<10-4). We conclude that the autoregulatory response is symmetric, and that coherent averaging can be combined effectively with our novel assessment method to elucidate the role of CrCP and RAP in the autoregulatory response.

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Accepted/In Press date: 3 October 2017
e-pub ahead of print date: 30 November 2017

Identifiers

Local EPrints ID: 419355
URI: http://eprints.soton.ac.uk/id/eprint/419355
ISSN: 0967-3334
PURE UUID: 71c4aef9-9c36-4b14-b7be-19ab60c43270

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Date deposited: 11 Apr 2018 16:30
Last modified: 26 Nov 2021 05:48

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Contributors

Author: Emmanuel Katsogridakis
Author: David Simpson
Author: Glen Blush
Author: Lingke Fan
Author: Anthony Birch
Author: Robert Allen
Author: John Potter
Author: Ronney Panerai

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