RESUMO
The severe elevations in blood pressure that occur in hypertensive emergencies pose a serious threat to life or vital organ functions. However, use of antihypertensive agents to acutely reduce blood pressure during hypertensive emergencies may cause deficits in the perfusion of the central nervous system or the heart. Therefore, a knowledge of cerebral blood flow regulation during acute treatment of hypertensive emergencies is indispensable. Experience with the calcium channel blocker nifedipine in the acute treatment of patients with hypertensive emergencies has shown that this agent has a pronounced vasodilatory effect, especially in vessels with a high vasoconstrictor tone, and that it does not reduce cardiac output or cerebral blood flow. The drug is highly efficacious and safe, and reports of serious side effects are rare. However, nifedipine should be used with caution in patients with suspected or proved critical arteriosclerotic stenosis of the cerebral arteries, because a reduction in perfusion pressure with any drug places these patients at risk for development of ischemic symptoms. Nifedipine can be used as a first-line drug for acute reduction of blood pressure in patients with hypertensive emergencies.