Intracranial Pressure Reduction By a Central Alpha-2 Adrenoreceptor Agonist After Subarachnoid Hemorrhage

Department

neurosurgery

Document Type

Article

Abstract

PHARMACOLOGICAL MANIPULATION OF cerebral venous blood volume is a theoretical approach to reduce elevated intracranial pressure (ICP). Microapplication of α-2 adrenoreceptor agonists has been shown to constrict pial veins selectively. This report explores the physiological effects of the intravenous α-2 agonist xylazine in a canine model of raised ICP after subarachnoid hemorrhage (mean arterial pressure, heart rate, and ICP were measured and compared in five groups: Normal saline [n = 4], xylazine [0.05–1.00 mg/kg] [n = 28], tolazoline [a semiselective α-2 antagonist, 5 mg/kg] [n = 6], tolazoline [5 mg/kg] plus xylazine [1.0 mg/kg] [n = 7], and phenylephrine [0.008 mg/kg], a selective α-1 agonist [n = 3]). Treatment with xylazine produced a significant (P < 0.01), transient, dose-dependent reduction in ICP that was blocked by pretreatment with tolazoline. Treatment with tolazoline alone produced significant (P < 0.01) increases in ICP and mean arterial pressure. Treatment with phenylephrine produced significant (P < 0.01) increases in mean arterial pressure but had no affect on ICP. These results raise the possibility of using an α-2 adrenoreceptor agonist for the treatment of elevated ICP after brain injury. © by the Congress of Neurological Surgeons.

Publication Date

1993

Publication Title

Neurosurgery

ISSN

0148-396X

Volume

32

Issue

6

First Page

974

Last Page

979

Digital Object Identifier (DOI)

10.1227/00006123-199306000-00016

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