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AS5.5 | Caudal Epidural Technique in Adults and Children — SDL Guide (Part 3)
Self-Assessment: Caudal Epidural Knowledge and Observation Readiness
This self-assessment step is designed to be completed after you have both studied this SDL and observed at least one caudal block procedure in a supervised clinical setting. The two activities are complementary — reading without observation leaves anatomical concepts abstract, and observation without prior reading means the procedure passes by as a series of unfamiliar gestures.
Test yourself: Can you identify the equilateral triangle landmark for the sacral hiatus on a pelvic skeleton model, or on a diagram, without labels? Can you explain why the dural sac terminus location differs between a neonate (S3–S4) and an adult (S2), and what the practical implication is for needle depth? Can you recall the Armitage formula volumes for sacral, lumbo-sacral, and lower thoracic block levels, and calculate the bupivacaine dose in mg/kg for a 12 kg child using 1.0 mL/kg of 0.25% bupivacaine — and recognise that this exceeds the maximum, requiring a concentration reduction?
On the clinical side: If the caudal block you observed appeared to work — the child was calm postoperatively — can you describe at least two intraoperative signs that the anaesthetist used to confirm adequacy? If there was a complication or block failure, do you understand what went wrong anatomically? If you observed a sacral swelling develop, could you explain to a nursing colleague what it means and why re-injection was delayed?
Review any gaps using Morgan & Mikhail (Chapter 45 — Paediatric Anaesthesia; Chapter 46 — Regional Anaesthesia) and Ajay Yadav's Essentials of Regional Anaesthesia. The NMC 2024 competency requires that you can observe and describe — your self-assessment target is not independent performance, but complete, accurate, anatomically-grounded description of everything that happens in a caudal block from positioning to postoperative assessment.
CLINICAL PEARL
The two most dangerous caudal errors and how to prevent them: (1) Advancing the needle too deep in an infant — the dural sac ends at S3–S4 in neonates, meaning a needle advanced 1.5 cm past the sacrococcygeal membrane can pierce the dura and inject the full epidural dose into the subarachnoid space, producing a total spinal with cardiovascular collapse. Prevention: never advance more than 1–2 mm past the membrane in infants; use ultrasound confirmation of tip position in neonates. (2) Exceeding the maximum bupivacaine dose in children — the volume formula (Armitage) does not include a dose check. A 10 kg child given 1.25 mL/kg of 0.25% bupivacaine for a "higher block" receives 3.1 mg/kg — exceeding the 2 mg/kg limit. LAST in a child is life-threatening and 20% intralipid dosing in paediatrics requires care. Prevention: always calculate mg/kg first; reduce concentration before increasing volume.