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Single-Shot Block Duration — FRCA Final MCQ

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EasyRegional AnaesthesiaSingle-Shot Block DurationFRCA Final

A 30-year-old man (ASA I, 72 kg) undergoes arthroscopic shoulder surgery in the beach-chair position with an interscalene nerve block and general anaesthesia. Two hours post-operatively he has no motor function in the blocked arm and cannot abduct his shoulder, flex his elbow, or extend his wrist. Sensation is absent from C5 to T1 distribution. How long after the block should recovery be expected?

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Correct answer: B — 12-24 hours

A single-shot interscalene brachial plexus block with a long-acting local anaesthetic (e.g., 20 mL 0.5% ropivacaine or 0.5% levobupivacaine) typically provides 12-24 hours of dense sensory and motor block. Block duration depends on: drug choice (ropivacaine/levobupivacaine > bupivacaine > lidocaine), concentration, volume, addition of adjuncts (dexamethasone or clonidine can extend to 24-36 hours), and individual patient factors. If block has not resolved by 48 hours, nerve injury should be suspected and investigated.

Reference: RCOA – 2023 – Regional anaesthesia: block duration; Hadzic A – 2017 – Textbook of Regional Anaesthesia