Sequential Changes of Cerebral Blood Flow after Acetazolamide Acetazolamide Loading in Hemodynamic Cerebral Ischemia: Relationship to Cerebral Oxygen Metabolism

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The aim of this study was to clarify relationship between sequential changes of cerebral blood flow (CBF) after acetazolamide loading and cerebral oxygen metabolism (CMRO_2). The subjects consisted of 30 patients with severe stenosis or occlusion of the internal carotid or middle cerebral or vertebro-basilar artery. Regional CBF was measured at the resting state and at 6, 16 and 30 minutes after the intravenous administration of 1 g acetazolamide using the [^<15>O]H_2 O bolus-injection method and positron emission tomography. Prior to CBF study, regional cerebral oxygen extraction fraction (OEF) was measured using the [^<15>O]O_2 inhalation method. Regional CMRO_2 was calculated based on CBF and OEF. Good response type (CBF increase rate more than 20% at 6 minutes after acetazolamide loading), paradoxical response type (decrease of CBF at 6 minutes after acetazolamide loading) and poor response type (CBF increase rate less than 20% at 6 minutes after acetazolamide loading) were identified in 39, 11 and 10 areas, respectively. Areas with good response type showed normal OEF and normal CMRO_2. Areas with paradoxical response type showed increased OEF. Areas with poor response type showed normal GEF and decreased CMRO_2. In view of these findings, the author concludes that sequential measurement of cerebral blood flow (CBF) after acetazolamide loading enables to know regional cerebral oxygen metabolic state in patients with hemodynamic ischemia, and CBF should be measured early after the administration of acetazolamide to accurately detect misery perfusion.