Carbonic anhydrase inhibitors have been used in clinical medicine as diuretics,1-3 as anticonvulsants,4,5 to reduce intraocular tension,6,7 to lower intracranial pressure,8,9 and in the treatment of respiratory insufficiency.10,11 In the course of investigation of the effects of acetazolamide in hepatic encephalopathy, Posner and Plum 12 observed without comment a considerable increase in rate of cerebral blood flow after intravenous administration of 1 to 2 gm. of acetazolamide. Such a cerebral circulatory change had previously been considered to account for the brief elevation of cerebrospinal fluid pressure after intravenous acetazolamide.9,13In view of these findings, we felt that the usefulness of carbonic anhydrase inhibitors might be extended to the management of patients with intermittent cerebral vascular insufficiency. In this preliminary report, observations of the quantitative cerebral hemodynamic effects of intravenous acetazolamide are presented. In several subjects, the effects of inhalation of 5% CO2 were also noted for comparative purposes.
MethodThe subjects of this investigation were 10 pa¬ tients hospitalized for clinical study of cerebral vascular disease believed to be the cause of cir¬ culatory insufficiency of internal carotid or vertebral-basilar artery systems. In all cases, the disorder was manifested by recurrent, transitory neurological dysfunction, considered on clinical grounds to involve the cerebral areas primarily supplied by the arterial systems noted, and assumed to be due to intermittent ischemia of these areas.Cerebral hemodynamic studies were performed before and 30 to 60 minutes after the intravenous administration of 1 gm. of acetazolamide (2 gm. in one instance) over a 10-minute period. In 8 of these patients, the effects of inhalation of S'%
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