What are the Society for Maternal-Fetal Medicine (SMFM) guidelines for managing severe maternal hypertension?

SMFM Guidelines for Severe Maternal Hypertension

According to the Society for Maternal-Fetal Medicine (SMFM) guidelines, severe maternal hypertension (BP ≥160/110 mmHg) requires immediate treatment with standard antihypertensive agents within 60 minutes of onset to reduce maternal morbidity and mortality. 1

Definition of Severe Hypertension

• Severe hypertension is defined as:

  • Systolic BP ≥160 mmHg, OR
  • Diastolic BP ≥110 mmHg, OR
  • Both 1

• A persistent severe hypertension episode is defined as:

  • BP not documented to have decreased to non-severe levels within 15 minutes, OR
  • One or more repeat severe hypertension observations documented at 15-60 minutes after episode onset, even if interspersed with non-severe BP readings 1

Recommended Treatment Protocol

First-Line Medications

SMFM recommends the following standard antihypertensive agents for severe maternal hypertension:

• Intravenous labetalol: 20,40, or 80 mg IV 1
• Intravenous hydralazine: 5 or 10 mg IV 1
• Oral nifedipine: 10 or 20 mg (immediate-release, not extended-release formulation) 1

Treatment Timeline

• Treatment should be initiated within 60 minutes of the onset of severe hypertension 1
• The goal is to reduce mean BP by 15-25% with target SBP 140-150 mmHg and DBP 90-100 mmHg 1
• BP should be monitored frequently after administration of antihypertensive medications

Quality Metric for Evaluating Treatment

SMFM has established a quality metric to evaluate timely treatment:

• Denominator: Number of obstetrical patients with one or more persistent severe hypertension episodes

• Numerator: Number of episodes in which EITHER:

  • A standard antihypertensive agent was administered within 60 minutes of episode onset, OR
  • A BP that is not severe hypertension is recorded and subsequent BPs are not in the severe range within 60 minutes of episode onset 1

• Ideal performance: 100% 1

Important Clinical Considerations

Medication Selection

• Labetalol is considered safe and effective for IV treatment of severe preeclampsia 1
• Hydralazine is widely used but may be associated with maternal hypotension, placental abruption, maternal oliguria, and fetal tachycardia 1
• Nifedipine should not be given concomitantly with magnesium sulfate due to risk of synergistic hypotension 1
• Methyldopa should not be used primarily for urgent BP reduction 1, 2

Monitoring

• Continuous maternal and fetal monitoring is essential during treatment 1
• Monitor for potential adverse effects:
  • Maternal hypotension (especially with hydralazine)
  • Fetal heart rate abnormalities
  • Signs of end-organ damage 1

Special Considerations

• Magnesium sulfate is recommended for seizure prophylaxis in preeclampsia but is not an antihypertensive agent 1
• Pain and other possible contributors to severe hypertension should be treated, but such treatment should not delay antihypertensive therapy 1

Pitfalls to Avoid

1. Delayed treatment: Failure to treat severe hypertension within 60 minutes increases risk of maternal stroke and death 1

2. Excessive BP reduction: Overly aggressive treatment may cause maternal hypotension and compromise uteroplacental perfusion 1

3. Inadequate monitoring: Lack of follow-up BP measurements may lead to unrecognized persistent severe hypertension 1

4. Using inappropriate medications: Using non-standard agents or incorrect dosing can lead to suboptimal outcomes 1

5. Failure to recognize persistent severe hypertension: Even a single severe BP reading without documented improvement within 15 minutes should be considered persistent severe hypertension 1

By following these SMFM guidelines for severe maternal hypertension, healthcare providers can significantly reduce maternal morbidity and mortality associated with hypertensive disorders in pregnancy.