Carbogen inhalation increases oxygen transport to hypoperfused brain tissue in patients with occlusive carotid artery disease: Increased oxygen transport to hypoperfused brain

• Published in: Brain research Vol. 1304; pp. 90 - 95
• Main Authors: ASHKANIAN, Mahmoud, GJEDDE, Albert, MOURIDSEN, Kim, VAFAEE, Manouchehr, VANG HANSEN, Kim, ØSTERGAARD, Leif, ANDERSEN, Grethe
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 22-12-2009
• Subjects: Adult; Aged; Aged, 80 and over; Air; Analysis of Variance; Biological and medical sciences; Brain - diagnostic imaging; Brain - physiopathology; Carbon Dioxide - therapeutic use; Carotid Artery Diseases - diagnostic imaging; Carotid Artery Diseases - physiopathology; Carotid Artery Diseases - therapy; Cerebrovascular Circulation - physiology; Female; Humans; Male; Medical sciences; Middle Aged; Neurology; Oxygen - metabolism; Oxygen - therapeutic use; Positron-Emission Tomography; Vascular diseases and vascular malformations of the nervous system; Vasoconstrictor Agents - therapeutic use; Human; Nervous system diseases; Internal carotid; Oxygen; Carbogen; Biological transport; CBF; Central nervous system; Cerebral hypoperfusion; Internal carotid artery disease; Cardiovascular disease; Cerebral disorder; Encephalon; Inhalation; Vascular disease; Central nervous system disease; Brain ischemia; Cerebrovascular disease; PET; Positron; Emission tomography
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2009.09.076

Hyperoxic therapy for cerebral ischemia reduces cerebral blood flow (CBF) principally from the vasoconstrictive effect of oxygen on cerebral arterioles. Based on a recent study in normal volunteers, we now claim that the vasodilatory effect of carbon dioxide predominates when 5% CO(2) is added to inhaled oxygen (the mixture known as carbogen). In the present study, we measured CBF by positron emission tomography (PET) during inhalation of test gases (O(2), carbogen, and atmospheric air) in healthy volunteers (n = 10) and in patients with occlusive carotid artery disease (n = 6). Statistical comparisons by an additive ANOVA model showed that carbogen significantly increased CBF by 7.51 + or - 1.62 ml/100 g/min while oxygen tended to reduce it by -3.22 + or - 1.62 ml/100 g/min. A separate analysis of the hemisphere contralateral to the hypoperfused hemisphere showed that carbogen significantly increased CBF by 8.90 + or - 2.81 ml/100 g/min whereas oxygen inhalation produced no reliable change in CBF (-1.15 + or - 2.81 ml/100 g/min). In both patients and controls, carbogen was as efficient as oxygen in increasing Sa(O2) or PaO(2) values. The study demonstrates that concomitant increases of CBF and Sa(O2) are readily obtained with carbogen, while oxygen increases only Sa(O2). Thus, carbogen improves oxygen transport to brain tissue more efficiently than oxygen alone. Further studies with more subjects are, however, needed to investigate the applicability of carbogen for long-term inhalation and to assess its therapeutic benefits in acute stroke patients.