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Updated: May 5, 2026
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Assessing Cerebral Autoregulation via Oscillatory Lower Body Negative Pressure and Projection Pursuit Regression
Published on: December 10, 2014
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Moderate hyperthermia impairs dynamic cerebral autoregulation but not its directional sensitivity
Mahmoudreza Taghizadeh1,2, Marc-Antoine Roy1,2, Shahrzad Soleimani Dehnavi1,2
1Department of Kinesiology, Faculty of Medicine, Université Laval, Québec City, Quebec, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 19, 2026
Summary
Moderate hyperthermia impairs dynamic cerebral autoregulation (dCA) by reducing blood flow buffering capacity, particularly at higher frequencies. However, it preserves the directional sensitivity of cerebral pressure-flow relationships.
Area of Science:
- Physiology
- Neuroscience
- Cardiovascular Research
Background:
- Dynamic cerebral autoregulation (dCA) is crucial for maintaining stable cerebral blood flow (CBF) amid blood pressure fluctuations.
- Whole-body hyperthermia can alter CBF regulation by increasing cerebrovascular resistance.
- The impact of hyperthermia on the directional sensitivity of dCA remains unclear.
Purpose of the Study:
- To investigate the effects of moderate hyperthermia on dCA and its directional sensitivity.
- To determine if hyperthermia alters the cerebrovascular buffering capacity during rapid blood pressure changes.
Main Methods:
- Twenty healthy adults underwent oscillatory lower body negative pressure (OLBNP) at 0.05 Hz and 0.10 Hz under normothermic and hyperthermic conditions.
- Transfer function analysis (TFA) and directional sensitivity analysis quantified dCA metrics.
- Middle cerebral artery mean blood velocity (MCAvmean) and mean arterial pressure (MAP) were continuously monitored.
Main Results:
- Hyperthermia impaired dCA, evidenced by increased TFA coherence, reduced TFA phase, and elevated TFA gain at 0.10 Hz.
- Directional sensitivity analysis revealed preserved directional patterns (%MCAvmeanT/%MAPT) across both frequencies under hyperthermia.
- Absolute directional sensitivity (∆MCAvmeanT/∆MAPT) was observed only at 0.10 Hz, with no significant thermal effect.
Conclusions:
- Moderate hyperthermia attenuates the dynamic buffering capacity of the cerebrovasculature, especially at higher frequencies.
- The inherent directional sensitivity of the cerebral pressure-flow relationship is maintained during moderate hyperthermia.
- Distinct regulatory mechanisms likely govern the dynamic and directional aspects of cerebral autoregulation.
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