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Updated: Jun 15, 2026
07:12
Evaluation of Cerebral Blood Flow Autoregulation in the Rat Using Laser Doppler Flowmetry
Published on: January 19, 2020
Effects of hypobaric hypoxia on cerebral autoregulation
Andrew W Subudhi1, Ronney B Panerai, Robert C Roach
1Altitude Research Center, University of Colorado at Denver, School of Medicine, Denver, CO, USA. asubudhi@uccs.edu
Stroke
|February 27, 2010
Summary
Hypoxia impairs cerebral autoregulation (CA), but this impairment does not cause acute mountain sickness (AMS). Further research is needed to understand AMS development during prolonged high-altitude exposure.
Area of Science:
- Physiology
- Altitude Medicine
- Neurology
Background:
- Acute hypoxia impairs cerebral autoregulation (CA).
- The role of altered CA in prolonged hypoxia-induced cerebral pathology, like acute mountain sickness (AMS), remains unclear.
Purpose of the Study:
- To investigate the relationship between cerebral autoregulation and AMS development over 9 hours of hypobaric hypoxia.
Main Methods:
- Fifty-five subjects were exposed to hypobaric hypoxia (4875 m).
- Beat-by-beat arterial blood pressure and middle cerebral artery blood flow velocity were recorded.
- Transfer function analysis estimated autoregulation indices (ARI); CO2 reactivity was also assessed.
Main Results:
- Cerebral autoregulation indices decreased and CO2 reactivity increased in both AMS-positive and AMS-negative groups at 4 hours, with no further progression at 9 hours.
- Despite worsening AMS symptoms, impaired CA did not correlate with AMS severity.
- Impaired CA was reversed by isocapnic hyperoxia and was independent of CO2 reactivity.
Conclusions:
- Hypoxia directly impairs cerebral autoregulation.
- Impaired cerebral autoregulation is not a pivotal factor in the development of acute mountain sickness.
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