What is the treatment for a pregnant patient with severe hypertension?

Treatment of Severe Hypertension in Pregnancy

For pregnant patients with severe hypertension, immediate treatment with intravenous labetalol is the first-line therapy, with intravenous hydralazine or oral nifedipine as acceptable alternatives, requiring immediate hospitalization to reduce maternal and fetal morbidity and mortality. 1

Definition and Classification of Hypertension in Pregnancy

Hypertension in pregnancy is defined as:

• Systolic blood pressure (SBP) ≥140 mmHg and/or diastolic blood pressure (DBP) ≥90 mmHg
• Severe hypertension: SBP ≥160 mmHg or DBP ≥110 mmHg

Hypertensive disorders in pregnancy include:

1. Pre-existing (chronic) hypertension
2. Gestational hypertension (developing after 20 weeks)
3. Pre-existing hypertension with superimposed gestational hypertension with proteinuria
4. Pre-eclampsia (hypertension with proteinuria ≥0.3 g/day)

Management of Severe Hypertension

Immediate Management

• Hospitalization is mandatory for severe hypertension (SBP ≥160 mmHg or DBP ≥110 mmHg)
• Parenteral therapy options 2, 1:
  1. IV Labetalol (first-line): Initial dose 20 mg (0.25 mg/kg), followed by additional doses of 40-80 mg every 10 minutes as needed, up to 300 mg cumulative dose
  2. IV Hydralazine: Alternative agent
  3. Oral Nifedipine: Alternative agent (immediate release)

Medication Selection Considerations

1. Labetalol (IV/Oral):

   • Alpha and beta-blocker with vasodilatory effects
   • Oral dosing: 100-400 mg twice daily (maximum 2400 mg/day)
   • IV dosing: 20 mg initial dose, followed by 40-80 mg every 10 minutes
   • Advantages: Does not cause reflex tachycardia, minimal effect on cardiac output 3
   • Caution: May worsen AV block, can cause bronchospasm in asthmatics 3

2. Nifedipine (Oral):

   • Extended-release formulation: 30-60 mg once daily
   • Caution: Avoid sublingual or IV administration due to risk of rapid BP reduction causing myocardial infarction or fetal distress 2
   • Warning: Do not combine with IV magnesium sulfate due to risk of synergistic hypotension 1

3. Methyldopa (Oral):

   • Dosing: 250-500 mg 2-4 times daily (maximum 3g/day)
   • Advantages: Longest safety record in pregnancy with long-term infant follow-up 1, 4
   • Disadvantages: Sedation, depression; should be switched postpartum 1

4. Hydralazine (IV/Oral):

   • Used for severe pre-eclampsia but found to be inferior to other agents 2

Contraindicated Medications

• ACE inhibitors, ARBs, direct renin inhibitors: Contraindicated due to renal dysgenesis and fetotoxicity 2, 1
• Atenolol: Contraindicated due to risk of intrauterine growth restriction 1
• Diuretics: Controversial and generally avoided in pre-eclampsia due to reduced plasma volume 2

Management of Pre-eclampsia

• Magnesium sulfate: Well-established for severe pre-eclampsia and eclampsia 2
• Steroids: Should be given for 48 hours to accelerate lung maturation if gestation is <34 weeks 2
• Delivery: The only definitive treatment for pre-eclampsia 2, 1
• Close monitoring: Maternal and fetal surveillance is essential 2

Treatment Thresholds

• Severe hypertension (≥160/110 mmHg): Immediate treatment required 1, 5
• Moderate hypertension (150-159/100-109 mmHg): Treatment recommended 2, 6
• Mild hypertension (140-149/90-99 mmHg): Treatment decisions based on:
  • Presence of gestational hypertension with/without proteinuria
  • Pre-existing hypertension with superimposed gestational hypertension
  • Presence of organ damage or symptoms 2

Postpartum Management

• Hypertension may worsen 3-6 days postpartum 1
• Continue BP monitoring for at least 6 weeks postpartum 1
• Switch from methyldopa to alternative agents in the postpartum period 1
• Target BP for breastfeeding patients: 120-150/70-100 mmHg 1

Long-term Considerations

• Women with hypertension during pregnancy have increased lifetime cardiovascular risk 1, 7
• Annual cardiovascular risk assessments are recommended 1
• Lifestyle modifications including weight management and regular exercise are advised 1

Key Pitfalls to Avoid

1. Delayed treatment of severe hypertension: Can lead to maternal stroke, organ damage, and death
2. Overly aggressive BP reduction: Can impair uteroplacental perfusion and harm the fetus
3. Using contraindicated medications: ACE inhibitors, ARBs, and direct renin inhibitors can cause severe fetal harm
4. Combining calcium channel blockers with IV magnesium: Can cause dangerous hypotension
5. Failing to recognize progression to pre-eclampsia: Requires close monitoring for proteinuria and other signs
6. Inadequate postpartum monitoring: Hypertension can worsen in the days after delivery

Remember that treatment of severe hypertension in pregnancy is an emergency requiring prompt intervention to prevent serious maternal and fetal complications.