Massive transfusion calcium — FRCA Primary MCQ

Correct answer: C — Citrate binds ionised calcium

Citrate in blood products can chelate ionised calcium. Hypocapnia causes cerebral vasoconstriction is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Perfusion of non-ventilated alveoli creates shunt is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Increased preload increases stroke volume through fibre stretch is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Chronic hypertension shifts cerebral autoregulation right is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA physiology, the correct answer is usually the variable that best explains the observed change in the anaesthetised patient.

Reference: West's Respiratory Physiology; Ganong Review of Medical Physiology; Primary FRCA textbooks