Intracranial Pressure Reduction By a Central Alpha-2 Adrenoreceptor Agonist After Subarachnoid Hemorrhage
PHARMACOLOGICAL MANIPULATION OF cerebral venous blood volume is a theoretical approach to reduce elevated intracranial pressure (ICP). Microapplication of Î±-2 adrenoreceptor agonists has been shown to constrict pial veins selectively. This report explores the physiological effects of the intravenous Î±-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 [0.05â€“1.00 mg/kg] [n = 28], tolazoline [a semiselective Î±-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 Î±-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 Î±-2 adrenoreceptor agonist for the treatment of elevated ICP after brain injury. Â© by the Congress of Neurological Surgeons.
Digital Object Identifier (DOI)
McCormick, John M.; McCormick, Patrick W.; Zabramski, Joseph M.; and Spetzler, Robert F., "Intracranial Pressure Reduction By a Central Alpha-2 Adrenoreceptor Agonist After Subarachnoid Hemorrhage" (1993). Neurosurgery. 224.