Pregnancy: Hypertensive Emergency Recommendations Updated

Diana Phillips

January 28, 2015

Updated best practice recommendations for the emergency treatment of acute-onset, severe hypertension during pregnancy and the postpartum period include the addition of nifedipine as a first-line therapy.

In an updated opinion published in the February issue of Obstetrics & Gynecology, the American College of Obstetricians and Gynecologists Committee on Obstetric Practice reports that studies of the oral dihydropyridine calcium channel blocker reduced women's blood pressure more quickly than either intravenous labetalol or hydralazine, which are the current first-line treatments, and produced a significant increase in urine output.

Although previous reports have suggested that simultaneous use of nifedipine and magnesium sulfate, the drug of choice for seizure prevention and treatment in severe preeclampsia and eclampsia, may cause neuromuscular blockade and severe hypotension, the association was not substantiated in a large retrospective study, the authors write. They note, however, that careful monitoring is advisable because both drugs are calcium antagonists.

The updated committee opinion includes order sets for the initial management of acute-onset severe hypertension in this patient population for each of the first-line treatment agents and points specifically to variations in the recommended dosage intervals, which reflect differences in the drugs' pharmacokinetics.

"Although all three medications are appropriately used for the treatment of hypertensive emergencies in pregnancy, each agent can be associated with adverse effects," the authors write. Possible adverse effects include increased risk for maternal hypotension with parenteral hydralazine, maternal heart rate increase and overshoot hypotension with oral nifedipine, and neonatal bradycardia with parenteral labetalol.

Parenteral labetalol, in particular, should be avoided in women with asthma, heart disease, or congestive heart failure, the authors stress.

When urgent treatment is needed before the establishment of intravenous access, the oral nifedipine algorithm can be initiated as intravenous access is being obtained, or a 200-mg dose of labetalol can be administered orally. The latter can be repeated in 30 minutes if appropriate improvement is not observed, the authors write.

Failure of the first-line therapies as outlined in the order sets is rare, but in situations in which severe hypertension persists, the committee recommends emergent consultation with an anesthesiologist, maternal-fetal medicine subspecialist, or critical care subspecialist to discuss second-line interventions. "Second-line alternatives to consider include labetalol or nicardipine by infusion pump," the authors write.

The committee opinion also calls for the adoption of standardized, evidence-based clinical guidelines for managing patients with preeclampsia. "With the advent of pregnancy hypertension guidelines in the United Kingdom, care of maternity patients with preeclampsia or eclampsia improved significantly and maternal mortality rates decreased because of a reduction in cerebral and respiratory complications," they write. "Individuals and institutions should have mechanisms in place to initiate the prompt administration of medication when a patient presents with a hypertensive emergency," the authors stress, noting that the use of checklists may help facilitate this process.

The authors have disclosed no relevant financial relationships.

Obstet Gynecol. 2015;125:521-525. Full text

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