Reversal of experimental cerebral vasospasm by intravenous nitroprusside therapy.

Cerebral vasospasm was induced in dogs by intracisternal injection of blood. After angiographic demonstration of spasm, sodium nitroprusside was infused intravenously and its effect on the diameter of the basilar artery was studied angiographically. Ten experiments were performed within 90 minutes of the induction of spasm and nine experiments were performed 24 or 48 hours later. Significant dilatation of the basilar artery was achieved in all cases and it persisted for as long as the infusion of nitroprusside continued. The drug produced a modest degree of systemic hypotension. In six experiments it was possible to avoid hypotension by a simultaneous infusion of dopamine.