Spinal Block Recovery Duration — FRCA Final MCQ

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EasyRegional AnaesthesiaSpinal Block Recovery DurationFRCA Final

A 40-year-old man (ASA II, 80 kg) has a spinal anaesthetic with 3.5 mL 0.5% heavy bupivacaine (17.5 mg) for a knee arthroscopy. Two hours post-operatively he cannot move his legs and reports no sensation below the umbilicus. What is the expected motor recovery time for this dose?

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Correct answer: E — 4-6 hours

Heavy bupivacaine 0.5% at 17.5 mg (a relatively high dose for knee arthroscopy – typical dose 10-15 mg) produces a dense motor and sensory block lasting 3-6 hours depending on dose and individual factors. At 2 hours post-injection, persistent dense block is expected and not concerning. Motor block recovers before sensory block. If block has not regressed at all by 6 hours, or if there are progressive neurological symptoms (worsening weakness, severe back pain, bladder dysfunction), urgent investigation for spinal cord/cauda equina compression (MRI) is required.

Reference: RCOA – 2023 – Regional anaesthesia: spinal block recovery; Bupivacaine pharmacology