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Lisfranc injury — MRCEM SBA MCQ

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HardAnkle and FootLisfranc injuryMRCEM SBA

A patient with metformin accumulation from acute kidney injury has shock despite resuscitation, lactate 23 mmol/L and pH 6.88. Which intervention most directly addresses both toxin burden and the refractory acid–base disturbance?

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Correct answer: D — Start urgent intermittent haemodialysis with critical-care support

The best answer is “Start urgent intermittent haemodialysis with critical-care support”. This is severe metformin-associated lactic acidosis meeting strong EXTRIP criteria for extracorporeal treatment. Intermittent haemodialysis efficiently removes metformin and lactate while correcting profound acidaemia; continuous renal replacement is an alternative when haemodynamic instability prevents intermittent treatment. Bicarbonate may be a temporary bridge but cannot provide adequate toxin removal and carries sodium and carbon-dioxide burdens. High-dose insulin treats calcium-channel-blocker shock, methylene blue treats methaemoglobinaemia, and peritoneal dialysis is too inefficient for this immediately life-threatening presentation.

Reference: EXTRIP Workgroup: metformin: https://www.extrip-workgroup.org/metformin