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Obstetric anaesthesia · Core17 / 17

Failed epidural extension, then high block at caesarean31-year-old woman, 112 kg (BMI 41), at 39 weeks in labour

Neuraxial caesarean: failed block options and managing a high block

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Know this first

  • Obese parturients need more top-ups and resites, and epidurals fail more often.
  • Spinal after a failed epidural is a risk factor for high block.
  • Surgery needs a T4 block.
  • Ketamine 0.2–0.4 mg/kg supplements inadequate regional block.
  • High block: vasopressor, fluids, uterine displacement, leg elevation; intubate if needed.

The patient

31-year-old woman, 112 kg (BMI 41), at 39 weeks in labour; her epidural needed three top-ups for one-sided pain over 6 hours. Failure to progress; semi-urgent caesarean (category 2). Otherwise well. Drugs: oxytocin infusion. Vitals: BP 124/78, HR 92, SpO2 98% on air, RR 18.

The examiner asks

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  1. Consider

    What are your concerns?

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    • A 31-year-old with BMI 41 for category 2 caesarean, with an unreliable labour epidural. Patient
    • Term and obesity: harder airway, faster desaturation, aspiration risk and caval compression.
    • Repeated top-ups for one-sided pain predict failed extension; obesity makes failure likelier. Disease
    • Category 2 gives time to choose between resite, spinal or general. Surgery

  2. Plan

    How will you anaesthetise her?

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    • This catheter failed in labour, so I'd resite it rather than trust it for surgery. Disease
    • Or a CSE: a spinal after top-ups risks a high block, so a smaller spinal dose.
    • The epidural part lets me extend if the block falls short.
    • Block tested to T4 before incision; she consents to general if she feels pain.
    • General ready: ramped, videolaryngoscope, nasal oxygen. Airway

  3. Crisis

    A resited epidural is extended; at skin incision she cries out. The block reaches T8 on the left, T6 on the right. BP 128/80, HR 104. What do you do?

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    • Stop surgery; operating through a patchy block is never acceptable. (Crisis)
    • A quick fix: epidural fentanyl 50–100 mcg, or more 2% lidocaine with adrenaline.
    • Short bridge: nitrous oxide 50%, or ketamine 0.2–0.4 mg/kg IV.
    • If pain persists despite top-ups, general anaesthesia; she must not suffer to avoid her airway.
    • Ramped rapid sequence: propofol 2 mg/kg, rocuronium 1.0 mg/kg.

  4. Crisis

    The top-ups don't fix it, so a colleague gives a full-dose spinal. Within 4 minutes she can't breathe properly, her hands are weak and she whispers; BP 70/40, HR 48. What do you do?

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    • High block: call for help, left uterine displacement kept, legs raised. Crisis
    • Ephedrine IV boluses with fluid running fast; no phenylephrine while she's bradycardic.
    • Atropine 1 mg IV every 3–5 minutes to 3 mg; adrenaline 2–10 mcg/min if no response.
    • Bag-mask with 100% oxygen; she is a full stomach, so I intubate early.
    • Rapid sequence with a reduced hypnotic dose; she may still be conscious though paralysed.
    • Kept ventilated and sedated until the block recedes; surgery proceeds. After surgery

Fatal mistakes

  • Operating through a patchy block.
  • A full spinal dose straight after epidural top-ups.
  • Delaying airway support in a high block.

Checked against: Miller 10e · Barash 9e

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