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Transfer function analysis of dynamic cerebral autoregulation in humans
R Zhang1, J H Zuckerman, C A Giller
1Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Texas 75231, USA.
The American Journal of Physiology
|February 12, 1998
Summary
Spontaneous changes in cerebral blood flow velocity are strongly linked to arterial pressure fluctuations, particularly at frequencies between 0.07-0.30 Hz. Cerebral autoregulation acts like a high-pass filter in this range.
Area of Science:
- Neuroscience
- Physiology
- Biomedical Engineering
Background:
- Cerebral blood flow regulation is crucial for brain function.
- Understanding cerebral autoregulation's frequency-dependent nature is key to interpreting blood flow dynamics.
Purpose of the Study:
- To investigate the relationship between arterial pressure and cerebral blood flow velocity.
- To determine if cerebral autoregulation is frequency-dependent.
Main Methods:
- Measured mean arterial pressure and middle cerebral artery velocity in 10 healthy subjects.
- Utilized transfer function analysis (Welch method) to assess frequency-dependent relationships.
- Calculated impulse response function to model transient changes.
Main Results:
- Cerebral blood flow velocity changes occurred simultaneously with arterial pressure changes.
- Transfer function gain increased with frequency (0.07-0.20 Hz), with high coherence (0.07-0.30 Hz).
- Model predictions closely matched measured velocity changes during hypotension.
Conclusions:
- Spontaneous cerebral blood flow changes (0.07-0.30 Hz) are strongly related to arterial pressure.
- Cerebral autoregulation functions as a high-pass filter for short-term arterial pressure regulation (0.07-0.30 Hz).