What is the most appropriate treatment for a pregnant patient at 35 weeks gestation presenting with a generalized seizure and hypertension?

Treatment of Eclamptic Seizure at 35 Weeks Gestation

The most appropriate treatment is magnesium sulfate (Option C), which is the definitive therapy for preventing and treating eclamptic seizures in this pregnant patient presenting with a generalized seizure and severe hypertension.

Immediate Management Priorities

Seizure Control and Prevention

• Magnesium sulfate is the first-line agent for eclamptic seizures, with proven superiority over other anticonvulsants including phenytoin in preventing seizures in hypertensive pregnant women 1.
• The standard loading dose is 4-6 g IV over 10-15 minutes, followed immediately by 5 g IM into each buttock, with maintenance dosing of 5 g IM every 4 hours or continuous IV infusion 2, 3.
• Magnesium sulfate should be continued for 24 hours postpartum in most cases 2.
• Magnesium sulfate approximately halves the seizure rate in patients with preeclampsia and is recommended for all women with severe hypertension (≥160/110 mmHg) with proteinuria or neurological symptoms 2, 4.

Blood Pressure Management

• This patient's BP of 166/92 mmHg requires urgent antihypertensive treatment since BP >160/110 mmHg lasting >15 minutes warrants immediate drug therapy 4.
• First-line agents for acute severe hypertension include:
  • Oral nifedipine: 10 mg PO, repeat every 20 minutes to maximum 30 mg 4
  • IV labetalol: 20 mg bolus, then 40 mg after 10 minutes, then 80 mg every 10 minutes to maximum 220 mg 4
  • IV hydralazine: 5 mg bolus, then 10 mg every 20-30 minutes to maximum 25 mg 4

Why Other Options Are Incorrect

Carbamazepine (Option A)

• Carbamazepine is not indicated for eclamptic seizures and has no role in the acute management of eclampsia 1.
• Magnesium sulfate has been proven superior to traditional anticonvulsants for eclampsia prevention 1.

Enalapril (Option B)

• ACE inhibitors are absolutely contraindicated in the second and third trimesters due to risk of fetal renal dysgenesis 5.
• While this patient requires antihypertensive therapy, enalapril is never appropriate in pregnancy beyond the first trimester 5.

Terbutaline (Option D)

• Terbutaline is a tocolytic agent used to suppress preterm labor, which is completely inappropriate for this clinical scenario 5.
• At 35 weeks with eclampsia, delivery is indicated, not tocolysis 4, 5.

Critical Safety Considerations

Magnesium Sulfate Monitoring

• Monitor for magnesium toxicity by checking patellar reflexes before each dose, maintaining urine output >100 mL/4 hours, and ensuring respiratory rate >16 breaths/minute 6.
• Therapeutic magnesium levels range from 4-8 mEq/L (3-6 mg/100 mL); reflexes diminish at >4 mEq/L and may be absent at 10 mEq/L with risk of respiratory paralysis 6.
• Have IV calcium gluconate immediately available to counteract magnesium toxicity 6.

Drug Interaction Warning

• Do not combine magnesium sulfate with calcium channel blockers (like nifedipine) without careful monitoring, as this can cause precipitous blood pressure drops and myocardial depression 2, 5.
• If using nifedipine for blood pressure control, administer it separately from magnesium sulfate boluses and monitor closely 4.

Fluid Management

• Limit total fluid intake to 60-80 mL/hour to prevent pulmonary edema, as preeclamptic patients are at high risk for this complication 2, 5.
• Aim for euvolemia while avoiding dehydration, which increases acute kidney injury risk 5.

Delivery Planning

• At 35 weeks with eclampsia, delivery should be planned once maternal condition is stabilized 4, 5.
• The presence of a seizure with severe hypertension constitutes an indication for delivery regardless of gestational age 4, 5.
• Continue magnesium sulfate through delivery and for 24 hours postpartum 2.