AS5.1-2 | Principles, Indications and Anatomy for Regional Anaesthesia — Summary & Reflection

KEY TAKEAWAYS

Regional anaesthesia is the selective interruption of nerve conduction using local anaesthetics, preserving airway reflexes and consciousness. Differential block follows an autonomic > sensory > motor sequence. Indications include primary surgical anaesthesia, high-risk patients, postoperative analgesia, and labour. Key anatomy: the lumbar layers (skin → supraspinous ligament → interspinous ligament → ligamentum flavum → epidural space → dura → subarachnoid space/CSF) and the brachial plexus (Roots C5–T1 → Trunks → Divisions → Cords → Terminals). Spinal block uses a small dose directly into CSF — fast, dense, single-shot; epidural uses a catheter into the epidural space — larger volume, slower, titratable. Never swap them. Bupivacaine is the most cardiotoxic LA (maximum 2 mg/kg, no IV use); LAST is treated with 20% intralipid. Hypotension from sympathectomy is the most common complication — treat with position, fluids, phenylephrine/ephedrine.

REFLECT

Think about a patient in your institution who was listed for major surgery under GA but who, on reflection, was a better candidate for regional anaesthesia. What factors would you weigh? Now consider the anatomy you studied — if you were to palpate the lumbar spine of a patient in the foetal position, could you reliably identify the L3/L4 interspace? What would make that identification difficult, and how might ultrasound or fluoroscopy help? Finally, recall the maximum dose of bupivacaine (2 mg/kg) — commit this number to memory, because dose errors with bupivacaine have caused deaths in patients who could not be resuscitated.