AS5.{3,6} | Peripheral Nerve Blocks and Common Surgical Blocks — Summary & Reflection

KEY TAKEAWAYS

Peripheral nerve blocks achieve targeted anaesthesia by depositing LA adjacent to specific nerves or plexuses, sparing haemodynamic stability and airway reflexes. The brachial plexus is blocked at four levels — interscalene (roots/trunks, shoulder), supraclavicular (trunks, whole arm but pneumothorax risk), infraclavicular/axillary (cords/terminals, elbow/forearm/hand). Lower limb blocks include femoral nerve block (anterior thigh/knee) and sciatic block — popliteal approach covers the leg below knee. The musculocutaneous nerve always needs a separate injection in an axillary block. TAP block covers the anterior abdominal wall only — not visceral pain. Ultrasound guidance is standard: identify the nerve, place the needle in-plane, confirm circumferential LA spread. Assess block at 10–20 minutes (temperature, pinprick, motor). LAST — CNS excitation then cardiovascular collapse — is the major systemic complication; treat with 20% intralipid 1.5 mL/kg bolus. Phrenic nerve block is universal with interscalene technique and contraindicated if contralateral phrenic is compromised.

REFLECT

When you next observe a peripheral nerve block in theatre or the emergency department, challenge yourself to predict — before the anaesthetist confirms — what the patient will and will not be able to feel after the block. Map it on your hand or leg: if this is an axillary block, which finger territory will be most reliably blocked? Which will need the supplementary musculocutaneous injection? If this is a femoral nerve block for a knee replacement, why is the patient still likely to need postoperative opioids for the first 24 hours (hint: the posterior knee joint capsule and the sciatic nerve territory)? Observation becomes education when you predict, watch the outcome, and reflect on where your mental model was correct or incomplete.