Use of middle cerebral velocity and blood pressure for the analysis of cerebral autoregulation at various frequencies: The coherence index

Cole A. Giller, Domenico Gerardo Iacopino

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

A common component in many protocols for the evaluation of cerebral autoregulation is the comparison of transcranial Doppler ultrasound (TCD) velocities with blood pressure recordings, in which correlations between these two signals correspond to impaired autoregulation. With long data sets and complicated paradigms, however, visual inspection alone cannot adequately distinguish random coincidence from consistent correlation in a statistically valid fashion. We suggest and illustrate the use of the coherence index for this purpose. To illustrate this technique, long-term recordings of TCD velocity and blood pressure were obtained from 6 normal subjects and using 23 data segments from 8 patients following subarachnoid hemorrhage. Each signal was first normalized to its mean, and coherence calculated by dividing the data into overlapping subintervals and computing an average. Coherence was specifically examined over time periods of 30 sec. Coherence calculations identified correlations between signals for which interpretation by visual inspection was unclear, and obvious correlations could be quantified. In 4 of the 6 normal subjects, the coherence was less than 0.60 but slightly greater than 0. Five of the 8 patients showed segments with coherence of greater than 0.60. The coherence index provides a quantitative tool for the evaluation of comparisons between two complex signals. As this task becomes more common in the evaluation of cerebral autoregulation, algorithms of this sort will become increasingly necessary.

Original languageEnglish (US)
Pages (from-to)634-640
Number of pages7
JournalNeurological Research
Volume19
Issue number6
DOIs
StatePublished - Jan 1 1997
Externally publishedYes

Fingerprint

Doppler Ultrasonography
Homeostasis
Blood Pressure
Subarachnoid Hemorrhage
Datasets

Keywords

  • Cerebral autoregulation
  • Hemodynamics
  • Transcranial Doppler ultrasound

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

Cite this

Use of middle cerebral velocity and blood pressure for the analysis of cerebral autoregulation at various frequencies : The coherence index. / Giller, Cole A.; Iacopino, Domenico Gerardo.

In: Neurological Research, Vol. 19, No. 6, 01.01.1997, p. 634-640.

Research output: Contribution to journalArticle

@article{b12882175d0e4fcc9b1c7af47ca5f666,
title = "Use of middle cerebral velocity and blood pressure for the analysis of cerebral autoregulation at various frequencies: The coherence index",
abstract = "A common component in many protocols for the evaluation of cerebral autoregulation is the comparison of transcranial Doppler ultrasound (TCD) velocities with blood pressure recordings, in which correlations between these two signals correspond to impaired autoregulation. With long data sets and complicated paradigms, however, visual inspection alone cannot adequately distinguish random coincidence from consistent correlation in a statistically valid fashion. We suggest and illustrate the use of the coherence index for this purpose. To illustrate this technique, long-term recordings of TCD velocity and blood pressure were obtained from 6 normal subjects and using 23 data segments from 8 patients following subarachnoid hemorrhage. Each signal was first normalized to its mean, and coherence calculated by dividing the data into overlapping subintervals and computing an average. Coherence was specifically examined over time periods of 30 sec. Coherence calculations identified correlations between signals for which interpretation by visual inspection was unclear, and obvious correlations could be quantified. In 4 of the 6 normal subjects, the coherence was less than 0.60 but slightly greater than 0. Five of the 8 patients showed segments with coherence of greater than 0.60. The coherence index provides a quantitative tool for the evaluation of comparisons between two complex signals. As this task becomes more common in the evaluation of cerebral autoregulation, algorithms of this sort will become increasingly necessary.",
keywords = "Cerebral autoregulation, Hemodynamics, Transcranial Doppler ultrasound",
author = "Giller, {Cole A.} and Iacopino, {Domenico Gerardo}",
year = "1997",
month = "1",
day = "1",
doi = "10.1080/01616412.1997.11740873",
language = "English (US)",
volume = "19",
pages = "634--640",
journal = "Neurological Research",
issn = "0161-6412",
publisher = "Maney Publishing",
number = "6",

}

TY - JOUR

T1 - Use of middle cerebral velocity and blood pressure for the analysis of cerebral autoregulation at various frequencies

T2 - The coherence index

AU - Giller, Cole A.

AU - Iacopino, Domenico Gerardo

PY - 1997/1/1

Y1 - 1997/1/1

N2 - A common component in many protocols for the evaluation of cerebral autoregulation is the comparison of transcranial Doppler ultrasound (TCD) velocities with blood pressure recordings, in which correlations between these two signals correspond to impaired autoregulation. With long data sets and complicated paradigms, however, visual inspection alone cannot adequately distinguish random coincidence from consistent correlation in a statistically valid fashion. We suggest and illustrate the use of the coherence index for this purpose. To illustrate this technique, long-term recordings of TCD velocity and blood pressure were obtained from 6 normal subjects and using 23 data segments from 8 patients following subarachnoid hemorrhage. Each signal was first normalized to its mean, and coherence calculated by dividing the data into overlapping subintervals and computing an average. Coherence was specifically examined over time periods of 30 sec. Coherence calculations identified correlations between signals for which interpretation by visual inspection was unclear, and obvious correlations could be quantified. In 4 of the 6 normal subjects, the coherence was less than 0.60 but slightly greater than 0. Five of the 8 patients showed segments with coherence of greater than 0.60. The coherence index provides a quantitative tool for the evaluation of comparisons between two complex signals. As this task becomes more common in the evaluation of cerebral autoregulation, algorithms of this sort will become increasingly necessary.

AB - A common component in many protocols for the evaluation of cerebral autoregulation is the comparison of transcranial Doppler ultrasound (TCD) velocities with blood pressure recordings, in which correlations between these two signals correspond to impaired autoregulation. With long data sets and complicated paradigms, however, visual inspection alone cannot adequately distinguish random coincidence from consistent correlation in a statistically valid fashion. We suggest and illustrate the use of the coherence index for this purpose. To illustrate this technique, long-term recordings of TCD velocity and blood pressure were obtained from 6 normal subjects and using 23 data segments from 8 patients following subarachnoid hemorrhage. Each signal was first normalized to its mean, and coherence calculated by dividing the data into overlapping subintervals and computing an average. Coherence was specifically examined over time periods of 30 sec. Coherence calculations identified correlations between signals for which interpretation by visual inspection was unclear, and obvious correlations could be quantified. In 4 of the 6 normal subjects, the coherence was less than 0.60 but slightly greater than 0. Five of the 8 patients showed segments with coherence of greater than 0.60. The coherence index provides a quantitative tool for the evaluation of comparisons between two complex signals. As this task becomes more common in the evaluation of cerebral autoregulation, algorithms of this sort will become increasingly necessary.

KW - Cerebral autoregulation

KW - Hemodynamics

KW - Transcranial Doppler ultrasound

UR - http://www.scopus.com/inward/record.url?scp=0031441027&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031441027&partnerID=8YFLogxK

U2 - 10.1080/01616412.1997.11740873

DO - 10.1080/01616412.1997.11740873

M3 - Article

C2 - 9427966

AN - SCOPUS:0031441027

VL - 19

SP - 634

EP - 640

JO - Neurological Research

JF - Neurological Research

SN - 0161-6412

IS - 6

ER -