Difficult Airway in Obstetrics

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Physiological Changes & Risks - Obstetric Airway Quirks

  • Airway Mucosa: Hormonal effects → capillary engorgement, edema (pharynx, larynx, trachea) → narrowed, friable airway. ↑Mallampati score.
  • Respiratory: ↓FRC by ~20%, ↑O2 consumption by ~20% → rapid O2 desaturation during apnea. Reduced safe apnea time.
  • Aspiration Risk: ↓LES tone, delayed gastric emptying (progesterone) → "full stomach"; ↑Mendelson's syndrome risk.
  • Anatomical Factors: Weight gain (↑neck circumference, pharyngeal tissue), enlarged breasts → difficult laryngoscopy & mask ventilation.
  • Hemodynamics: Supine hypotension (aortocaval compression) can compromise maternal/fetal perfusion.

⭐ Failed intubation: ~8x higher risk in obstetrics (~1:250) vs. general surgery.

Prediction & Assessment - Spotting Trouble Early

  • Standard Tools:
    • 📌 LEMON: Look, Evaluate (3-3-2 rule: IIG >3FB, HMD >3FB, Thyrohyoid >2FB), Mallampati (≥III), Obstruction, Neck mobility.
    • Key cut-offs: TMD < 6 cm; IIG < 3 cm (<2FB); Neck circumference > 40 cm; Sternomental < 12.5 cm.
  • Obstetric Considerations:
    • Physiological changes: Airway edema (↑ labor, preeclampsia, tocolytics), breast engorgement, ↓FRC (rapid desat), ↑O₂ demand.
    • ↑ Aspiration risk (↓LES tone).

⭐ Difficult intubation is 8 times more common in obstetric patients than in the general surgical population.

Management Algorithm - Obstetric Airway Crisis Drill

  • Immediate Actions:
    • Call experienced help (Anesthesia, OB, Neonatal).
    • Difficult airway cart.
  • Pre-oxygenation & Positioning:
    • 100% O2 (3-5 min / 4 VC breaths).
    • RAMP position. Left Uterine Displacement (LUD).
  • Intubation (Plan A):
    • Max 2-3 attempts. Short handle. Video Laryngoscope (VL) preferred.
    • Consider cricoid pressure.
  • Rescue (Plan B/C):
    • Supraglottic Airway Device (SGA) (LMA/i-gel) if intubation fails.
    • Effective Face Mask Ventilation (FMV) with adjuncts.
  • CICO (Plan D):
    • Declare Cannot Intubate, Cannot Oxygenate (CICO) early if O2 fails.
    • Front of Neck Access (FONA) - surgical cricothyroidotomy.
  • Key Principles:
    • Prioritize maternal oxygenation.
    • Minimize trauma.
    • Consider Awake Fiberoptic Intubation (AFOI) for anticipated Difficult Airway (DA).

⭐ Physiological changes in pregnancy (↓ Functional Residual Capacity (FRC), ↑O2 consumption, airway edema) cause rapid desaturation during apnea.

Advanced Management & Pharmacology - Special Tools & Drugs

  • Specialized Airway Devices:
    • Video Laryngoscopes (VL): Glidescope, C-MAC; better view.
    • Supraglottic Airways (SGA): 2nd gen (LMA Supreme, i-gel); better seal, gastric access.
    • Flexible Intubation Scope (FOB) for AFI/difficult cases.
    • Surgical airway: Cricothyroidotomy kits (e.g., Melker).
  • Key Pharmacological Agents:
    • Induction: Ketamine (stable hemodynamics), Propofol, Etomidate.
    • Muscle Relaxants: Succinylcholine (rapid); Rocuronium (Sugammadex reversal).
    • AFI: Local anesthetics, sedation (Remifentanil), Glycopyrrolate (↓secretions).

⭐ Sugammadex dose for immediate rocuronium reversal: 16 mg/kg.

High‑Yield Points - ⚡ Biggest Takeaways

  • Physiological changes in pregnancy (airway edema, ↓FRC, ↑O2 consumption) significantly increase difficult airway risk.
  • Mallampati score often worsens during labor; meticulous airway assessment is vital.
  • Obstetric patients have a higher incidence of failed intubation (approx. 1:250).
  • Aspiration prophylaxis and Rapid Sequence Intubation (RSI) are critical for general anesthesia.
  • Ensure immediate availability of a Difficult Airway Cart and skilled assistance.
  • Prioritize regional anesthesia; consider awake intubation for anticipated difficult airways.

Practice Questions: Difficult Airway in Obstetrics

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Which of the following lung volumes remains unchanged during pregnancy?

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Flashcards: Difficult Airway in Obstetrics

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_____ anesthesia is the first choice for most patients with preeclampsia during labor, vaginal delivery, and cesarean section

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_____ anesthesia is the first choice for most patients with preeclampsia during labor, vaginal delivery, and cesarean section

Epidural

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