What is the immediate treatment for a pregnant woman with eclampsia?

Immediate Treatment for Eclampsia

Administer magnesium sulfate immediately as the first-line agent to stop active seizures and prevent recurrence, followed by urgent blood pressure control if BP ≥160/110 mmHg. 1, 2, 3

Magnesium Sulfate Administration Protocol

Loading Dose

• Give 4-6 grams IV over 20-30 minutes as the initial loading dose 4, 3
• Simultaneously, you may administer 5 grams IM in each buttock (total 10 grams IM) for a combined loading approach, particularly useful in settings with limited IV access (Pritchard protocol) 4, 3
• Alternatively, give the 4 gram IV loading dose alone, followed immediately by maintenance infusion 3

Maintenance Dose

• Continue with 1-2 grams/hour by continuous IV infusion using a controlled infusion pump 1, 4, 3
• For patients with BMI ≥25 kg/m², start at 2 grams/hour rather than 1 gram/hour to achieve therapeutic levels more reliably 4
• If using the Pritchard IM protocol, give 5 grams IM every 4 hours in alternating buttocks 4, 3

Duration of Therapy

• Continue magnesium sulfate for 24 hours postpartum in most cases 1, 4, 5
• Some evidence suggests women who received ≥8 grams before delivery may not require the full 24-hour postpartum course, but the 24-hour protocol remains the safer standard 1, 4
• Never exceed 5-7 days of continuous administration as this can cause fetal abnormalities 5, 3

Blood Pressure Management

Urgent Antihypertensive Therapy

• Treat immediately if BP ≥160/110 mmHg with one of the following agents 1:
  • Oral nifedipine (immediate-release) 1
  • IV labetalol 1
  • IV hydralazine 1
• Target diastolic BP of 85 mmHg (systolic 110-140 mmHg) 1

Critical Drug Interaction Warning

• NEVER combine magnesium sulfate with IV or sublingual nifedipine as this can cause severe myocardial depression and precipitous hypotension 2, 4, 5
• If using nifedipine for BP control, use oral immediate-release formulation with careful monitoring 2

Fluid Management

Strict Fluid Restriction

• Limit total fluid intake to 60-80 mL/hour to prevent pulmonary edema 1, 4, 5
• Preeclamptic/eclamptic women have capillary leak and are at high risk for pulmonary edema with excessive fluids 1, 5
• Replace insensible losses (30 mL/h) plus anticipated urinary losses (0.5-1 mL/kg/hour) 1
• Do NOT "run dry" as these patients are already at risk for acute kidney injury 5

Clinical Monitoring During Treatment

Essential Safety Monitoring

• Check deep tendon reflexes (patellar reflex) frequently - loss of reflexes occurs at magnesium levels of 3.5-5 mmol/L and is the first sign of toxicity 6
• Monitor respiratory rate continuously - maintain ≥12 breaths/minute; respiratory paralysis occurs at 5-6.5 mmol/L 2, 6
• Measure urine output hourly - maintain ≥30 mL/hour as magnesium is renally excreted 2, 4
• Monitor oxygen saturation - maintain >90% 2

Laboratory Monitoring

• Do NOT routinely check serum magnesium levels - clinical monitoring is sufficient in most cases 2
• Check serum magnesium only in specific high-risk situations: 2
  • Renal impairment (elevated creatinine)
  • Oliguria developing during treatment
  • Signs of toxicity despite normal clinical parameters
• Therapeutic magnesium level is 1.8-3.0 mmol/L (4.8-7.2 mg/dL) for seizure control 3, 6

Delivery Planning

Timing of Delivery

• Deliver as soon as the woman regains consciousness and is stabilized 7
• Eclampsia is an indication for delivery regardless of gestational age 1
• Vaginal delivery is preferred when feasible 7

Magnesium Sulfate Superiority Over Other Anticonvulsants

Evidence Base

• Magnesium sulfate is superior to phenytoin - in a randomized trial of 2,138 women, 10/1,089 (0.9%) assigned to phenytoin had eclamptic convulsions versus 0/1,049 (0%) assigned to magnesium sulfate (P=0.004) 8
• Magnesium sulfate is superior to diazepam for both preventing and controlling eclamptic seizures 2
• Benzodiazepines carry significant risks of respiratory depression in both mother and neonate 2

Common Pitfalls to Avoid

Medication Errors

• Avoid NSAIDs for postpartum pain in eclamptic patients as they worsen hypertension and increase acute kidney injury risk 1, 4
• Do not give oral antihypertensives during active labor - reduced GI motility decreases absorption; use IV agents instead 1, 4
• Never exceed 30-40 grams total magnesium sulfate in 24 hours 3
• In severe renal insufficiency, maximum dose is 20 grams/48 hours 5, 3

Monitoring Failures

• Do not rely solely on blood pressure - eclampsia can occur with only moderately elevated BP 9
• Remember that eclampsia can occur postpartum - 11-44% of cases occur after delivery, with increasing proportion beyond 48 hours postpartum 9
• Continue vigilant monitoring for at least 3 days postpartum with BP checks every 4-6 hours 1

Magnesium Toxicity Management

Signs of Toxicity (in order of severity)

• Loss of patellar reflexes: 3.5-5 mmol/L 6
• Respiratory depression: 5-6.5 mmol/L 6
• Altered cardiac conduction: >7.5 mmol/L 6
• Cardiac arrest: >12.5 mmol/L 6

Antidote

• Calcium gluconate 1 gram IV (10 mL of 10% solution) given slowly over 3 minutes reverses magnesium toxicity 6