Caudal block for hypospadias repair: collapse after injection2-year-old boy, 12 kg, healthy, born at term, for elective hypospadias repair
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Know this first
- Caudal 0.25% bupivacaine: 0.5 mL/kg reaches the sacral segments.
- Test dose: 0.1 mL/kg, maximum 3 mL, with adrenaline 0.5–1 mcg/kg; watch the ECG 30–60 s.
- Intravascular signs under GA: peaked T waves or ST change, then rising BP, sometimes tachycardia.
- In small children a total spinal shows as apnoea, not hypotension.
- PALS: start CPR if HR stays below 60 and perfusion is poor although ventilation is good.
The patient
The examiner asks
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Consider
What are your considerations?
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- A healthy 2-year-old, 12 kg, for elective hypospadias repair under GA with a caudal. Patient
- As a child he's dosed per kilogram; under GA he can't report early toxicity symptoms.
- Caudals work well under 2–3 years; his sacral hiatus is usually open at this age. Surgery
Plan
How do you perform the caudal safely?
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- I feel the hiatus between his two sacral cornua, the tip of a triangle with both PSIS. Surgery
- Ultrasound can confirm epidural spread and improves my success.
- 0.25% bupivacaine 0.5 mL/kg reaches the sacral segments his surgery needs. Patient
- Gentle aspiration first: blood or CSF means I don't inject. Surgery
- Test dose 0.1 mL/kg with adrenaline 0.5–1 mcg/kg, watching his ECG 30–60 seconds. Crisis
- Peaked T waves, ST change, or rising HR or BP mean intravascular: I stop.
- Then I inject slowly in 0.1–0.2 mL/kg steps, eyes on the ECG. Surgery
Crisis
Two minutes after the injection he stops breathing. SpO2 falls to 88%, BP 50/25, HR 70, and the QRS is widening. What do you do?
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- LAST in a child, run with PALS: apnoea and collapse right after his caudal. (Crisis)
- Stop injecting, call for help and the LAST kit; ventilate with 100% oxygen, then intubate.
- Ventilation comes first: hypoxia and acidosis make bupivacaine toxicity worse.
- Lipid 20%: 1.5 mL/kg over 2–3 minutes, then 0.25 mL/kg/min by pump.
- If his HR drops below 60 and perfusion stays poor despite good ventilation, CPR starts.
- Adrenaline under 1 mcg/kg in LAST, smaller than the usual 0.01 mg/kg arrest dose.
- Fluid in 10–20 mL/kg boluses, reassessing after each.
Crisis
Suppose instead he becomes apnoeic, but BP stays 86/48 and HR 115. What do you think, and what do you do?
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- Apnoea with a steady pressure suggests intrathecal spread: a total spinal in a child shows as apnoea. Crisis
- His circulation usually holds at this age, so ventilation is the treatment.
- Intubate, ventilate and keep him asleep until it wears off; spinals in small children are short.
- Afterwards I explain to his parents and check his leg movement before discharge. After surgery
Fatal mistakes
- A volume not worked out from his weight and the segments needed.
- Injecting despite blood or CSF on aspiration.
- Delaying ventilation while treating the blood pressure.
- No ECG watch during the test dose under general anaesthesia.
Checked against: Barash 9e · Miller 10e · AHA and AAP guidelines: pediatric advanced life support (2025) · ASRA Pain Medicine Local Anesthetic Systemic Toxicity checklist: 2020 version
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