Emergency Treatment of Severe Hypertension in Pregnant and Postpartum Women

Acute-onset hypertension lasting 15 minutes or longer in women with preeclampsia or eclampsia is a hypertensive emergency that requires antihypertensive treatment, according to a new Committee Opinion of The American College of Obstetricians and Gynecologists (The College).¹ Acute-onset, severe hypertension generally occurs in the second half of gestation in patients with no history of chronic hypertension but also can occur in patients with chronic hypertension who develop superimposed preeclampsia.

Severe hypertension is categorized by a systolic blood pressure of 160 mm Hg or greater or a diastolic blood pressure of 110 mm Hg or greater or both. Severe systolic hypertension is the most significant predictor of cerebral hemorrhage and infarction in pregnant and postpartum women with preeclampsia or eclampsia. If severe systolic hypertension is not immediately treated, maternal death can result.

Rather than normalizing blood pressure, the goal of treatment is to achieve a systolic blood pressure of 140 to 160 mm Hg and a diastolic pressure of 90 to 100 mm Hg. This blood pressure range prevents repeated, prolonged exposure of the patient to severe systolic hypertension, which can result in loss of cerebral vascular autoregulation. In all cases of acute persistent severe hypertension, maternal blood pressure should be stabilized before delivery, even if the fetus is in distress. The College also recommends close monitoring of both mother and fetus and judicious administration of fluid, even when oliguria is present or suspected.

First-line medications for managing acute-onset, severe hypertension in pregnant and postpartum women are intravenous labetalol and hydralazine. Tables 1 and 2 show the order sets for use of these medications for initial management of acute, persistent, severe hypertension. Each of these medications is associated with possible adverse effects. Parenteral labetalol may cause neonatal bradycardia and should be avoided in women with asthma or heart failure. Parenteral hydralazine may increase the risk of maternal hypotension.

Magnesium sulfate is not recommended as an antihypertensive agent but remains the medication of choice for seizure prophylaxis in severe preeclampsia and for controlling seizures in eclampsia.

The College suggests labetalol or nicardipine administered by infusion pump as second-line therapies for controlling acute-onset severe hypertension. Sodium nitroprusside should be a last-resort treatment in extreme emergencies and used for the shortest possible duration because of possible thiocyanate toxicity in the mother and fetus or newborn and increased cranial pressure with potential worsening of cerebral edema in the mother.

 
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References:

Reference
1. Committee opinion no. 514: emergent therapy for acute-onset, severe hypertension with preeclampsia or eclampsia. Obstet Gynecol. 2011;118:1465.