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Updated: Aug 2, 2026

MRI Mapping of Cerebrovascular Reactivity via Gas Inhalation Challenges
Published on: December 17, 2014
[Cerebral hemodynamics in carbon dioxide applications]
T J Doering1, M Konitzer, T Hausner
1Abteilung Allgemeinmedizin, Medizinische Hochschule Hannover, Germany. Doering.Thorsten@mh-hannover.de
Introduction:
We compare the effect of carbon dioxide (CO(2)) dry and wet applications on cerebral hemodynamics.
Methods:
On 22 volunteers measurements were taken during CO(2) application. 10 probands were examined in CO(2) wet application (1,100-1,300 mg/l) and 12 probands in CO(2) dry application (500 g in a 800 l bathtub). The cerebral blood flow velocity (CBFV) in the middle cerebri artery (MCA) was measured as a parameter of cerebral hemodynamics by means of transcranial doppler sonography. Furthermore were recorded CO(2) expiratory concentration (CO(2)et), blood pressure, and sublingual temperature.
Results:
At CO(2) wet application the CBFV increased during therapy phase by 15% (p = 0.001), parallel to the rise of the CO(2)et by 18% (p = 0.01). During CO(2) dry application CBFV decreased by 11% (p = 0.007), body temperature increased significantly by 0.2 degrees C.
Conclusion:
CO(2) applications have influence on cerebral hemodynamics. Assuming constant diameters of the great brain vessels, CO(2) wet application shows a raising and CO(2) dry application a reducing influence on cerebral blood flow. This influence will attain therapeutic relevance.
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