A trauma patient receives 12 units of whole blood over 90 minutes. He develops perioral tingling, carpopedal spasm, a prolonged QT interval, and worsening hypotension. Ionised calcium is 0.85 mmol/L. What is the mechanism and treatment?
- A Hyperkalaemia from the storage lesion; give insulin-dextrose
- B Citrate chelation of calcium; give intravenous calcium gluconate ✓
- C Hypomagnesaemia; give intravenous magnesium sulphate
- D Transfusion-related circulatory overload; give furosemide
Correct answer: B. Citrate chelation of calcium; give intravenous calcium gluconate
Explanation
The anticoagulant citrate in banked blood chelates ionised calcium. With rapid large-volume transfusion, hepatic citrate metabolism is overwhelmed, producing hypocalcaemic tetany, QT prolongation, and hypotension. Treatment is IV calcium gluconate or chloride. Hyperkalaemia is also part of the storage lesion but produces peaked T waves and widened QRS rather than tetany and QT prolongation, which identifies calcium chelation here.
Reference: Sabiston Textbook of Surgery, 21st ed.
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