Hypertensive emergency is a condition in which there is elevation of both systolic and diastolic blood pressure with the presence of acute target organ disease.
Hypertensive urgency is a condition where the blood pressure is elevated (diastolic > 120 mmHg) with the absence of acute target organ disease.
Hypertensive emergencies are best managed with parenteral drugs and careful intraarterial blood pressure monitoring.
Hydralazine has been widely used in treatment of
hypertension in
eclampsia and
preeclampsia, and its safety has been demonstrated in these patients.
Sodium nitroprusside (SNP) has the most reliable
antihypertensive activity, which begins immediately after its administration and ends when the infusion is stopped. As with
diazoxide, it should be used with caution in patients with impaired cerebral flow. SNP is the preferred
drug in obtaining
controlled hypotension in patients undergoing neurovascular surgery. Intravenous
nitroglycerin is useful in patients prone to
myocardial ischemia, but should be avoided in patients with increased intracranial pressure.
Esmolol is effective in controlling both supraventricular
tachyarrhythmias and severe
hypertension. Its short onset of duration of action make it useful in the emergent setting, but because of its negative inotropic effect its use should be avoided in patients with
low cardiac output.
Verapamil should not be used in patients with preexisting conduction abnormalities.
Nicardipine is a potent arteriolar
vasodilator without a significant direct depressant effect on myocardium. As with other afterload
reducing agents, it should not be used in patients with severe
aortic stenosis. Because
angiotensin-converting enzyme (
ACE) inhibitors generally cause cerebral vasodilatation,
enalaprilat may be particularly beneficial for patients who are at high risk of developing cerebral hypotensive episodes secondary to impaired cerebral circulation.
Fenoldopam, a selective post-synaptic dopaminergic receptor (DA1) has been shown to be effective in treating severe
hypertension with a lower incidence of side effects than SNP.
Hypertensive urgencies can usually be managed with oral agents. Oral
nifedipine,
captopril,
clonidine,
labetalol,
prazosin, and
nimodipine have all been shown to be effective in these situations.