Improvement of brain tissue oxygenation by inhalation of carbogen

M. Ashkanian, P. Borghammer, A. Gjedde, L. Østergaard, M. Vafaee

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Hyperoxic therapy for cerebral ischemia is suspected to reduce cerebral blood flow (CBF), due to the vasoconstrictive effect of oxygen on cerebral arterioles. We hypothesized that vasodilation predominates when 5% CO2 is added to the inhaled oxygen (carbogen). Therefore, we used positron emission tomography (PET) to measure CBF and cerebral metabolic rate of oxygen (CMRO2) during inhalation of test gases (O2, CO2, carbogen and atmospheric air) in 10 healthy volunteers. Arterial blood gases were recorded during administration of each gas. The data were analyzed with volume-of-interest and voxel-based statistical methods. Inhalation of CO2 or carbogen significantly increased global CBF, whereas pure oxygen decreased global CBF. The CMRO2 generally remained unchanged, except in white matter during oxygen inhalation relative to condition of atmospheric air inhalation. The volume-of-interest results were confirmed by statistical cluster analysis. Oxygen and carbogen were equally potent in increasing oxygen saturation of arterial blood (SaO2). The present data demonstrate that inhalation of carbogen increases both CBF and SaO2 in healthy adults. In conclusion we speculate that carbogen inhalation is sufficient for optimal oxygenation of healthy brain tissue, whereas carbogen induces concomitant increases of CBF and SaO2.

Original languageEnglish (US)
Pages (from-to)932-938
Number of pages7
Issue number4
StatePublished - Oct 28 2008


  • CBF
  • OEF
  • brain tissue oxygenation
  • carbogen
  • oxygen

ASJC Scopus subject areas

  • Neuroscience(all)


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