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AV Fistula Regional Anaesthesia — FRCA Final MCQ

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ModerateRegional AnaesthesiaAV Fistula Regional AnaesthesiaFRCA Final

A 50-year-old man with end-stage kidney disease on haemodialysis three times weekly presents for formation of a radiocephalic arteriovenous fistula in the left forearm. He has severe chronic obstructive pulmonary disease with limited respiratory reserve, so the risk of hemidiaphragmatic paralysis should be minimised. A single-injection brachial plexus technique is required that provides rapid, reliable anaesthesia of the lateral forearm, including the musculocutaneous nerve territory, without separate terminal-nerve injections. Which nerve block is most appropriate?

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Correct answer: A — Infraclavicular brachial plexus block

The infraclavicular coracoid block is the best fit. It blocks the cords before they divide into terminal nerves, so a single-injection technique is more likely to cover the musculocutaneous nerve and lateral forearm promptly. In a randomised trial in uraemic patients undergoing forearm fistula creation, musculocutaneous sensory block developed faster and more completely with infraclavicular than single-injection axillary block. It also causes substantially less hemidiaphragmatic paralysis than supraclavicular block, although the risk is not zero. Interscalene block commonly affects the phrenic nerve and may spare the inferior trunk. Axillary block is phrenic-sparing, but reliable modern performance generally requires separate terminal-nerve injections, often including the musculocutaneous nerve. A wrist block does not cover the lateral forearm incision or provide proximal brachial plexus sympathetic blockade.

Reference: Niemi TT et al. Single-injection brachial plexus anesthesia for arteriovenous fistula surgery of the forearm: a comparison of infraclavicular coracoid and axillary approach. Regional Anesthesia and Pain Medicine. 2007;32(1):55-59. https://pubmed.ncbi.nlm.nih.gov/17196493/