Intrapartum and Emergency Management & Prevention

Emergency Parenteral Therapy for Severe Hypertension During Pregnancy

TABLE 14-3

Agent	Action	Dose	Side Effects	Comments
Hydralazine	Direct vasodilator	5 mg IV over 1–2 min, then 5–10 mg IV every 20–40 min until blood pressure is 130–150/80–100 mm Hg. If no response after 20–25 mg, switch to another drug. Alternatively, give continuous IV infusion of 0.5–10 mg/hr.	Headache, tachycardia, flushing, vomiting	Increases cardiac output and probably uterine renal blood flow; has historically been drug of choice for short-term control.
Labetalol hydrochloride	Nonselective α1-blocker β1-blocker	Start with 10–20 mg IV bolus. If response is inadequate after 10 min, give 20–80 mg IV every 20–30 min if needed to lower blood pressure to 130–150/80–100 mm Hg. Total dose not to exceed 300 mg. Alternatively, give a continuous IV infusion of 1–2 mg/min.	Nausea, vomiting, heart block, bronchoconstriction, dizziness	Current drug of choice in many centers. Avoid if evidence of asthma or acute heart failure.
Nifedipine	Calcium channel blocker	10–20 mg orally; repeat in 30 min if inadequate response, then 10–20 mg every 2–6 hours if needed to lower blood pressure to 130–150/80–100 mm Hg.	Reflex tachycardia and headaches

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Intrapartum Management of Preeclampsia

Seizure ProphylaxisZ

Magnesium sulfate: 4-6 g IV loading dose over 20-30 minutes, followed by continuous infusion of 1-2 g/hour. Serial assessments of urine output, deep tendon reflexes, and respirations are important for detecting signs of magnesium toxicity.

Clinical Correlates of Serum Magnesium Sulfate Levels

TABLE 14-2

Clinical Response	Serum Levels* (mg/dL)
Loss of patellar reflex	8-12
Warmth and flushing	9-12
Somnolence	10-12
Slurred speech	10-12
Paralysis and respiratory difficulty	15-17
Cardiac arrest	30-35

*Therapeutic range: 4.8-9.6 mg/dL.

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Management of Magnesium Toxicity

Magnesium toxicity is treated by stopping the infusion and administering IV calcium gluconate along with resuscitative measures if necessary.

Antihypertensive Therapy

Caution not to lower the arterial pressure too much or too rapidly, for either may result in a decreased uteroplacental blood flow and fetal distress, which may necessitate an emergency cesarean delivery in an unstable mother.

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Management of Eclampsia

1. (ABC) Protect airway and administer oxygen.
2. Roll to left side and provide suction to minimize aspiration.
3. Prevent injury by padding side rails.
4. Administer MgSO4 to prevent further seizures.
5. When stable, plan for mode of delivery.

Fetal ConsiderationsZ

Eclamptic seizures often induce a fetal bradycardia that usually resolves after maternal stabilization and correction of hypoxia, unless there is a placental abruption.

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Prevention of Preeclampsia

Aspirin

81 mg/day for 12-28 weeks starting at 12 weeks.