A patient with end-stage renal disease on haemodialysis requires elective surgery. Dialysis was performed the previous day. Which electrolyte abnormality is of greatest immediate anaesthetic concern and why?
- A Hypernatraemia causing osmotic demyelination
- B Hypocalcaemia causing neuromuscular irritability
- C Hyperphosphataemia causing metastatic calcification
- D Hyperkalaemia causing cardiac arrhythmias, aggravated by succinylcholine-induced serum potassium rise ✓
Explanation
Hyperkalaemia is the most immediately life-threatening electrolyte abnormality in ESRD patients. Succinylcholine causes an average serum K+ rise of 0.5–1.0 mEq/L due to ACh receptor-mediated membrane depolarisation; in chronic denervation, immobilisation, burns, or ESRD patients with elevated baseline K+, this can trigger fatal ventricular arrhythmias. If K+ is >5.5 mEq/L pre-operatively, elective surgery should be postponed and dialysis performed. Non-depolarising agents are safe. Serum K+ should ideally be <5.0 mEq/L before anaesthesia in ESRD. Succinylcholine is contraindicated if K+ >5.5 mEq/L.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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