RSI in Eclampsia: Induction & Paralytic Agents

Key Background Consideration

Induction Agent

Ketamine — Preferred in most emergency/unstable scenarios

• Maintains hemodynamic stability (sympathomimetic)
• Dose: 1–1.5 mg/kg IV
• Provides analgesia + amnesia
• Caution: At doses >2 mg/kg, can raise blood pressure — use with care if severe hypertension is uncontrolled
• Preferred for hemodynamically unstable or actively seizing patients

Thiopental — Historically preferred in obstetric anesthesia

• Dose: 4–5 mg/kg IV (reduced if hemodynamically compromised)
• Anticonvulsant properties — beneficial in eclampsia
• Rapid onset, rapid redistribution
• Still used widely where available; crosses placenta but neonatal depression at standard doses is manageable

Propofol

• Dose: 1.5–2 mg/kg IV
• Anticonvulsant, reduces ICP and CMRO₂
• Risk of hypotension — use cautiously in eclampsia patients with already compromised uteroplacental perfusion
• More suitable if blood pressure is very high and controlled

Etomidate

• Dose: 0.3 mg/kg IV
• Excellent hemodynamic stability
• Avoids BP drop — suitable when hypertension is a concern and thiopental/ketamine are unavailable
• Single dose for RSI is acceptable (adrenal suppression less relevant for one-time use)

Paralytic Agent

Succinylcholine — Standard first choice

• Dose: 1.5 mg/kg IV (some sources suggest up to 2 mg/kg if MgSO₄ is on board)
• Fastest onset (~45–60 sec), ultra-short duration
• Critical interaction: MgSO₄ potentiates and prolongs succinylcholine block — monitor closely, consider dose reduction or use with caution
  • Morgan and Mikhail's Clinical Anesthesiology, 7e — explicitly notes that magnesium sulfate at doses used to treat preeclampsia/eclampsia prolongs onset and duration of succinylcholine
• Provides ideal intubating conditions rapidly

Rocuronium — Alternative (especially if succinylcholine is contraindicated)

• Dose: 1.2 mg/kg IV (high dose for RSI conditions)
• Onset: ~60 seconds at this dose
• Duration significantly prolonged by MgSO₄ — neuromuscular block may last much longer than expected
• Reversible with sugammadex (16 mg/kg) — important safety advantage in a "can't intubate, can't oxygenate" scenario

Summary Table

Critical Pearls for Eclampsia RSI

1. MgSO₄ potentiates ALL neuromuscular blockers — both depolarizing and non-depolarizing. Expect prolonged block; have neuromuscular monitoring.
2. Avoid ketamine if BP is uncontrolled (>160/110 refractory to antihypertensives) — it can further raise BP.
3. Aspiration risk is high (full stomach, pregnancy) — RSI with cricoid pressure is standard.
4. Pre-treat hypertensive response to laryngoscopy with labetalol, esmolol, or lidocaine before intubation.
5. Difficult airway is more common in obstetric patients — have backup plan (video laryngoscope, surgical airway).

Management of Urticaria in Antenatal Women

General Principle

Step-by-Step Management

Step 1 — Identify and Remove Triggers

• Eliminate causative agents: foods (nuts, shellfish, eggs), drugs (NSAIDs, penicillin), infections
• Avoid physical triggers (cold, pressure, heat) if inducible urticaria
• Note: pregnancy-specific urticarial eruptions (see below) require a separate approach

Step 2 — First-Line: H1 Antihistamines

Key point: Cetirizine and loratadine are the preferred second-generation antihistamines — desirably used after the first trimester when benefits outweigh individual risks. Chlorphenamine is often chosen for its extensive safety record.

Step 3 — Second-Line Therapies (if antihistamines fail)

• H2 antagonists (ranitidine/famotidine): may be added as adjunct to H1 antihistamines for refractory cases
• Omalizumab (anti-IgE): data in pregnancy is limited; case reports show use in severe refractory chronic urticaria — decision should be individualised with specialist input

Can Steroids Be Given?

Short-term/rescue use: ✅ Acceptable

• Oral prednisolone/prednisone is effective for nearly all presentations of urticaria
• Indicated for:
  • "Crisis" urticaria — severe acute flares not responding to antihistamines
  • Serious angioedema of the throat (airway risk)
  • PUPPP/PEP — topical corticosteroids are the standard first-line treatment in most cases; systemic prednisolone is used in severe cases
• A single dose or short course (several days) is sufficient to re-establish control alongside regular antihistamines

Long-term use: ❌ Should be avoided

• Regular/prolonged oral corticosteroids in chronic urticaria are discouraged even in non-pregnant patients because of:
  • Predictable long-term side effects: hypertension, gestational diabetes, weight gain, osteoporosis
  • Rebound flares on discontinuation
  • Prolonged duration of chronic urticaria makes this approach unsustainable
• Prednisolone is preferred over prednisone in pregnancy — prednisolone is inactivated by placental 11β-hydroxysteroid dehydrogenase, resulting in lower fetal exposure (~10% of maternal levels)
• Avoid dexamethasone and betamethasone for urticaria (they cross the placenta readily; reserved for fetal lung maturity)

Special Case: Pregnancy-Specific Urticarial Eruptions

Anaphylaxis / Life-Threatening Urticaria

Summary Algorithm

Urticaria in Pregnancy
│
├─ Mild → Trigger removal + Chlorphenamine or Cetirizine/Loratadine (after T1)
│
├─ Moderate-Severe → Up-titrate antihistamine ± H2 blocker
│
├─ Refractory/"Crisis" → Short course prednisolone (30–50 mg/day, few days)
│                         Taper with antihistamines
│
└─ Anaphylaxis → Epinephrine IM immediately