Citrate toxicity in massive transfusion — FRCA Primary MCQ

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HardPhysiologyCitrate toxicity in massive transfusionFRCA Primary

During massive transfusion, a shocked patient develops hypotension, prolonged QT interval and ionised calcium 0.72 mmol/L. Which mechanism best explains this?

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Correct answer: E — Citrate binding of ionised calcium

Stored blood products contain citrate, which binds ionised calcium; rapid transfusion can cause hypocalcaemia, hypotension and QT prolongation. Potassium may rise during massive transfusion, but potassium chelation by lactate is not the mechanism. Albumin release from red cells and vitamin K excess do not explain the findings. Ionised calcium should be monitored and replaced during major haemorrhage.

Reference: Ganong Review of Medical Physiology; Association of Anaesthetists major haemorrhage guidance