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(Stroke. 1974;5:607.)
© 1974 American Heart Association, Inc.

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Cerebrovascular CO₂ Reactivity of the Fast and Slow Clearing Compartments

LINNETTE D. ILIFF PH.D.¹; E. ZILKHA M.Sc.¹; G. H. DU BOULAY M.B., M.R.C.P., F.F.R.¹; JOHN MARSHALL M.D., F.R.C.P.(ED), F.R.C.P.(LOND), D.P.M.¹; R. W. ROSS RUSSELL M.A., M.D., D.M., F.R.C.P.¹; LINDSAY SYMON F.R.C.S. (ED), F.R.C.S. (ENG)¹

¹ Institute of Neurology, National Hospital for Nervous Diseases, Queen Square, London WCIN 3BG, England

Regional cerebral blood flow measurements have been made at two levels of PaCO₂, using the clearance of ¹³³Xenon injected into the internal carotid artery. Specific and percent changes in blood flow per mm Hg change in PaCO₂. (CO₂ reactivity) have been calculated for the fast and slow clearing tissue (Ff and Fs) and F initial. Mean hemisphere CO₂ reactivity was marginally greater in the fast clearing tissue than in the slow clearing tissue (P = 0.05). On a regional basis the greater CO₂, reactivity of Ff over Fs was significant in five areas (P 0.05). A strong positive linear correlation between mean specific reactivity and conductance (the reciprocal of resistance) has been demonstrated for Ff and Fs and confirmed in the F initial.

Key Words: ¹³³Xenon • internal carotid artery • regional cerebral blood flow