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Renal Failure and Suxamethonium — FRCA Final MCQ

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ModeratePreoperative AssessmentRenal Failure and SuxamethoniumFRCA Final

A 62-year-old man (ASA III) with end-stage kidney disease receiving haemodialysis presents for creation of a left-arm arteriovenous fistula. A non-haemolysed blood sample taken immediately before theatre shows a serum potassium concentration of 5.8 mmol/L. His ECG is normal. If general anaesthesia with neuromuscular blockade is required, which statement is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Avoid suxamethonium because he has pre-existing hyperkalaemia

Explanation lettering: D = shown as A · A = shown as B · B = shown as C · E = shown as D · C = shown as E

A is correct. The current, non-haemolysed potassium of 5.8 mmol/L establishes pre-existing hyperkalaemia despite the normal ECG. Suxamethonium ordinarily raises serum potassium by about 0.5 mmol/L, and its UK SmPC lists hyperkalaemia from any cause as a contraindication. Renal failure by itself does not prohibit one normal dose, making B true only for a dialysis patient without hyperkalaemia. Propofol should be titrated to clinical effect; an ASA III patient may need a reduced dose, not an empirically increased dose. End-stage kidney disease is not an absolute contraindication to brachial plexus blockade, although coagulation status and anticoagulant use must be assessed. Volatile anaesthetics are not collectively contraindicated. Sugammadex should not be presented as routine backup here because its SmPC does not recommend use in dialysis-dependent severe renal impairment.

Reference: Martindale Pharma. Suxamethonium Chloride 50 mg/ml Solution for Injection/Infusion, Summary of Product Characteristics, sections 4.2–4.4; text revised 2025. https://www.medicines.org.uk/emc/product/3401/smpc