Effect of intracisternal phentolamine on cerebral blood flow after subarachnoid injection of blood

Abstract

The H clearance method was used to measure total and focal cerebral blood flow (CBF) in the rhesus monkey before and for 5 h after a simulated subarachnoid hemorrhage (SAH). Some monkeys also received 0.2 to 1.0 mg/kg phentolamine intracisternally 3 h after SAH. SAH did not change cerebrovascular resistance, but as cerebral perfusion pressure decreased, CBF fell transiently. Phentolamine injected intracisternally 3 h after SAH produced a significant fall in arterial blood pressure; cerebrovascular resistance did not change but CBF decreased significantly. Intracisternal phentolamine cannot be considered potentially useful to treat ischemic encephalopathy after SAH.