How to manage hypertensive crisis in a pregnant woman?

Management of Hypertensive Crisis in Pregnancy

Hypertensive crisis in pregnancy (BP >160/110 mmHg) requires immediate treatment with intravenous labetalol or oral nifedipine in a monitored setting to prevent maternal complications such as stroke and eclampsia. 1

Initial Assessment and Classification

• Definition of hypertensive crisis: BP ≥160/110 mmHg lasting >15 minutes in a pregnant woman 1
• Immediate concerns: Risk of maternal stroke, pulmonary edema, and eclampsia
• Maternal assessment: Check for:
  • Proteinuria (urine protein/creatinine ratio ≥30 mg/mmol is abnormal) 1
  • Neurological symptoms (headache, visual disturbances)
  • Signs of organ dysfunction (oliguria, epigastric pain)
  • Clonus and hyperreflexia

Emergency Treatment Algorithm

Step 1: Immediate BP Reduction

• Target: Reduce BP to 140-150/90-100 mmHg (not lower to avoid compromising placental perfusion) 1
• Timing: Treatment should be initiated within 30-60 minutes of confirmed severe hypertension 2
• First-line medications (in order of preference):
  1. IV Labetalol: 20 mg IV bolus initially, then 40 mg if not effective within 20 min, followed by 80 mg every 20 min up to maximum 300 mg 1, 3
  2. Oral Nifedipine: Immediate-release 10-20 mg, can repeat every 20-30 minutes (maximum 60 mg in first hour) 1, 4
  3. IV Hydralazine: 5 mg slow IV bolus, repeated every 20 minutes (maximum 5 doses) 1

Step 2: Seizure Prophylaxis

• Magnesium sulfate: Administer to women with preeclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs/symptoms 1
• Caution: Do not give magnesium sulfate concomitantly with calcium channel blockers due to risk of hypotension 1

Step 3: Refractory Hypertension

• If BP remains >160/110 mmHg after maximum doses of first-line agents:
  • Second-line agents: IV nicardipine (5-15 mg/hr) 5
  • Last resort: Sodium nitroprusside (0.25-5.0 μg/kg/min) - use with caution due to risk of fetal cyanide poisoning with prolonged use 1, 6
  • Consult anesthesiology, maternal-fetal medicine, or critical care specialists 2

Monitoring During Treatment

Maternal Monitoring

• Continuous BP monitoring every 10-15 minutes until stable
• Assess for signs of magnesium toxicity if administered (respiratory depression, loss of reflexes)
• Laboratory tests: CBC, platelets, liver enzymes, renal function, uric acid (twice weekly) 1
• Clinical assessment including clonus and neurological status 1

Fetal Monitoring

• Continuous fetal heart rate monitoring
• Ultrasound assessment of fetal growth and amniotic fluid volume
• Doppler studies if fetal growth restriction is suspected 1

Delivery Considerations

Delivery is indicated if any of the following occur:

• Gestational age ≥37 weeks 1
• Refractory severe hypertension despite three antihypertensive agents
• Progressive thrombocytopenia
• Worsening liver or renal function
• Pulmonary edema
• Neurological complications (severe headache, visual changes, seizures)
• Non-reassuring fetal status 1

Postpartum Management

• BP typically rises in the first 5 days after delivery 1
• Continue monitoring BP for at least 72 hours in hospital and 7-10 days postpartum 4
• Avoid methyldopa postpartum due to risk of depression 4
• Preferred agents: Nifedipine, labetalol, enalapril 4

Common Pitfalls and Caveats

• Do not reduce BP too rapidly or too low - can compromise placental perfusion
• Never use ACE inhibitors, ARBs, or direct renin inhibitors during pregnancy 4
• Avoid diuretics as they may reduce plasma volume and worsen placental perfusion 4
• Avoid atenolol due to risk of fetal growth restriction 4
• Do not delay treatment - maternal stroke can occur with untreated severe hypertension
• Remember long-term follow-up - women with hypertensive disorders of pregnancy have increased lifetime cardiovascular risk 4

The most recent evidence from the International Society for the Study of Hypertension in Pregnancy (2018) provides clear guidance on managing hypertensive crisis in pregnancy, emphasizing the importance of prompt treatment in a monitored setting to reduce maternal and fetal morbidity and mortality.