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Evaluation of Cerebral Blood Flow Autoregulation in the Rat Using Laser Doppler Flowmetry
Published on: January 19, 2020
Central hypervolemia with hemodilution impairs dynamic cerebral autoregulation
Yojiro Ogawa1, Ken-ichi Iwasaki, Ken Aoki
1Department of Hygiene and Space Medicine, Nihon University School of Medicine, Tokyo, Japan.
Anesthesia and Analgesia
|October 26, 2007
Summary
Central hypervolemia with hemodilution impairs dynamic cerebral autoregulation, affecting blood flow regulation. This study investigated changes in cerebral blood flow during altered blood volumes.
Area of Science:
- Physiology
- Neuroscience
- Critical Care Medicine
Background:
- Perioperative central blood volume fluctuations can impact cerebral autoregulation via sympathetic activity, cardiac output, blood viscosity, and vasomotor tone.
- Dynamic cerebral autoregulation during acute, wide-ranging central blood volume changes, particularly central hypervolemia with hemodilution, remains understudied.
Purpose of the Study:
- To evaluate dynamic cerebral autoregulation during induced central hypovolemia and central hypervolemia with hemodilution.
- To investigate the effects of altered central blood volume on the relationship between mean arterial blood pressure and cerebral blood flow velocity.
Main Methods:
- Assessed dynamic cerebral autoregulation in 12 individuals using spectral and transfer function analysis.
- Manipulated central blood volume via lower body negative pressure and normal saline infusions.
- Measured central venous pressure and cardiac output using impedance cardiography.
Main Results:
- Steady-state cerebral blood flow velocity and cardiac output decreased with lower body negative pressure and increased with saline infusion, without significant mean arterial blood pressure changes.
- Transfer function gain between mean arterial blood pressure and cerebral blood flow velocity variability significantly increased post-saline infusion.
- Indicated an increased transfer of mean arterial blood pressure oscillations to cerebral blood flow fluctuations during central hypervolemia with hemodilution.
Conclusions:
- Steady-state cerebral blood flow velocity is altered by both central hypervolemia and hypovolemia.
- Dynamic cerebral autoregulation is impaired specifically during central hypervolemia with hemodilution.
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