Treatment of hypertensive emergencies of pregnancy.

The terminology, pathophysiology, and therapy of acute hypertensive emergencies of pregnancy are reviewed. A hypertensive emergency of pregnancy can be defined to include any of the following: (1) an acute increase in blood pressure to values greater than 160/110 mm Hg, (2) development of symptoms consistent with severe preeclampsia, or (3) symptoms consistent with known complications of uncontrolled blood pressure. A hypertensive emergency requires hospitalization, immediate antihypertensive treatment to reduce maternal blood pressure without substantially decreasing placental perfusion and compromising the fetus, and delivery of the infant as soon as possible. Hydralazine has been shown to decrease blood pressure effectively in hypertensive emergencies of pregnancy. Although many institutions consider hydralazine the antihypertensive agent of choice in pre-eclampsia/eclampsia, there have been no comparative studies to document that hydralazine is the safest or most efficacious agent and only one human study evaluated its effects on maternal blood pressure, fetal heart rate, growth retardation, and uterine activity. Based on available data, minibolus doses or infusion over 20-30 minutes of diazoxide may prove to be safe and effective alternatives to hydralazine, but more data are needed. Nitroprusside may have a role in the short-term treatment of patients unresponsive or intolerant to hydralazine, but human studies are needed before nitroprusside can be recommended routinely. Methyldopa cannot be considered a first-choice agent for the rapid reduction of blood pressure because of its slow onset of action. Further studies are needed before propranolol, i.v. nitroglycerin, captopril, clonidine, minoxidil, naldolol, atenolol, or metoprolol can be recommended. Until further studies are conducted, hydralazine will continue to be the treatment of choice for hypertensive emergencies of pregnancy.