TS1 - Cerebral AutoRegulation Network
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Transcript TS1 - Cerebral AutoRegulation Network
Multimodal Pressure-Flow Analysis to
Assess Dynamic Cerebral Autoregulation
Albert C. Yang, MD, PhD
Attending Physician, Department of Psychiatry,
Taipei Veterans General Hospital, Taipei, Taiwan
Assistant Professor, School of Medicine,
National Yang-Ming University, Taipei, Taiwan
[email protected]
Overview
What is cerebral autoregulation and how to
measure it?
Multimodal pressure-flow analysis
Empirical Mode Decomposition and Hilbert-Huang
Transform
Subsequent improvement
Demonstration
Body as Servo-Mechansim Type Machine
• Importance of corrective mechanisms to
keep variables “in bounds.”
• Healthy systems are self-regulated to
reduce variability and maintain
physiologic constancy.
Perturbation
Baseline
Restored steady state
Underlying notion of “constant,” “steady-state,” conditions.
Walter Cannon 1929
Ideal Cerebral Autoregulation
Lassen NA. Physiol Rev. 1959;39:183-238
Strandgaard S, Paulson OB. Stroke.1984;15:413-416
Static Autoregulation Measurement
Tiecks FP et al., Stroke. 1995; 26: 1014-1019
Dynamic Autoregulation Measurement
Tiecks FP et al., Stroke. 1995; 26: 1014-1019
Autoregulation Index
Tiecks FP et al., Stroke. 1995; 26: 1014-1019
Challenges of Cerebral
Autoregulation Assessment
• Blood pressure and cerebral blood flow
velocity are often nonstationary and their
interactions are nonlinear.
• Need a new method that can analyze
nonlinear and nonstationary signals.
Novak V et al., Biomed Eng Online. 2004;3(1):39
Multimodal Pressure-Flow Analysis
Participants
15 normotensive healthy subjects
20 hypertensive subjects
age 40.2 ± 2.0 years
age 49.9 ± 2.0 years
15 minor stroke subjects
18.3 ± 4.5 months after acute onset
age 53.1 ± 1.6 years
Novak V et al., Biomed Eng Online. 2004;3(1):39
Measurements
Blood pressure
Finger Photoplethysmographic Volume Clamp
Method.
Blood flow velocities (BFV) from bilateral middle
cerebral arteries (MCA)
Transcranial Doppler Ultrasound.
Novak V et al., Biomed Eng Online. 2004;3(1):39
Valsalva Maneuver
Arterial Blood Pressure
HHT residual
180
I. Expiration - 160
mechanical
IV
I
mmHg
140
IV. increased cardiac
output and increased
peripheral resistance
120
100
80
III
60
II. reduced venous return,
BP falls 40
20
30
40
III. Inspiration - mechanical
II
50
Time (sec)
60
70
80
Valsalva Maneuver Dynamics
Blood Pressure
Blood Flow Velocity – Right Middle Cerebral Artery
Blood Flow Velocity – Left Middle Cerebral Artery
Empirical Mode Decomposition (EMD)
黃 鍔 院士
Norden E. Huang
The Empirical Mode Decomposition
Method and the Hilbert Spectrum for
Non-stationary Time Series Analysis,
(1998) Proc. Roy. Soc. London, A454,
903-995.
The motivation of EMD development was
to solve the problems of non-linearity and
non-stationarity of the data
Is an adaptive-based method
Cited 7,722 Times!
Empirical Mode Decomposition
Huang et al. Proc Roy Soc Lond A 1998;454:903-995.
Empirical Mode Decomposition
Step 1: Find the envelope alone local maximum and minimum
Huang et al. Proc Roy Soc Lond A 1998;454:903-995.
Empirical Mode Decomposition
Step 2: Find the average between envelopes
Huang et al. Proc Roy Soc Lond A 1998;454:903-995.
Empirical Mode Decomposition
Intrinsic Mode Function
Step 3: To determine the fluctuation of original signal
around the average of envelopes
Huang et al. Proc Roy Soc Lond A 1998;454:903-995.
Empirical Mode Decomposition
Sifting : to get all IMF components
x( t ) c1 r1 ,
r1 c2 r2 ,
. . .
rn 1 cn rn .
x( t )
n
c
j 1
j
rn .
Huang et al. Proc Roy Soc Lond A 1998;454:903-995.
Original Data
Empirical Mode Decomposition
A Simple Example
2
0
-2
0
10
20
30
40
50
60
0
10
20
30
40
50
60
0
10
20
30
40
50
60
0
10
20
30
40
50
60
IMF 1
1
0
-1
IMF 2
1
0
IMF 3
-1
0.5
0
-0.5
Empirical Mode
Decomposition
Original blood pressure
waveform
Key mode of blood
pressure waveform
during Valsalva
maneuver
Blood Pressure versus Blood Flow Velocity
Temporal (time) Relationship
Novak V et al., Biomed Eng Online. 2004;3(1):39
Blood Pressure versus Blood Flow Velocity
Phase Relationship
Control
Stroke
Novak V et al., Biomed Eng Online. 2004;3(1):39
Between Groups Phase Comparisons
*** p < 0.005,
** p < 0.01
Groups BPR Values Comparisons
+++ p <0.001
Conventional Autoregulation Indices
Novak V et al., Biomed Eng Online. 2004;3(1):39
Summary: Original Version of
MMPF Analysis
Regulation of BP-BFV dynamics is altered in
both hemispheres in hypertension and stroke,
rendering BFV dependent on BP.
The MMPF method provides high time and
frequency resolution.
This method may be useful as a measure of
cerebral autoregulation for short and
nonstationary time series.
Limitations: Original Version
of MMPF Analysis
Requires visual identification of key mode of
physiologic time series
Mode mixing with original EMD analysis
Valsalva maneuver itself has certain risk
Subsequent Improvements of
MMPF Analysis
Use Ensemble EMD (EEMD) Analysis
Wu, Z., et al. (2007) Proc. Natl. Acad. Sci. USA., 104, 14889-14894
Resting-state MMPF Analysis
K. Hu, et al., (2008) Cardiovascular Engineering
Selection of key mode related to respiration
during resting-state condition
M-T Lo, k Hu et al., (2008) EURASIP Journal on Advances in Signal Processing
Comparison of phase shifts in multiple time
scales
Hu K et al., (2012) PLoS Comput Biol 8(7): e1002601
Implementation and automation of the method
Dr. Yanhui Liu. DynaDx Corp. U.S.A.
Resting-State Multimodal
Pressure-Flow Analysis
K. Hu, et al., Cardiovascular Engineering, 2008.
Respiratory Signals From
Blood Pressure Time Series
M-T Lo, k Hu et al., EURASIP Journal on Advances in Signal Processing, 2008
Resting-State Multimodal
Pressure-Flow Analysis
Resting-State Multimodal
Pressure-Flow Analysis
Cerebral Blood Flow Regulation at
Multiple Time Scales
Hu K et al., PLoS Comput Biol 2012; 8(7): e1002601
Traumatic Brain Injury and
Cerebral Autoregulation
k. Hu, M-T Lo et al., journal of neurotrauma, 2009
Traumatic Brain Injury and
Cerebral Autoregulation
k. Hu, M-T Lo et al., journal of neurotrauma, 2009
Midline Shift Correlates to LeftRight Difference in Autoregulation
k. Hu, M-T Lo et al., journal of neurotrauma, 2009
Resources
Empirical Mode Decomposition (Matlab)
http://rcada.ncu.edu.tw/research1.htm
DataDemon (Generic Analysis Platform)
For 64-bit system,
https://dl.dropbox.com/u/7955307/daily_build/x64/Data
DemonSetupPRO.msi
For 32-bit system,
https://dl.dropbox.com/u/7955307/daily_build/x86/Data
DemonSetupPRO.msi
Acknowledgements
Vera Novak, MD, PhD
Yanhui Liu, PhD
Chung-Kang Peng, PhD
Kun Hu, PhD
Albert C. Yang, MD, PhD
Ment-Zung Lo, PhD