Hypothermia oxygen unloading — FRCA Primary MCQ

Correct answer: D — Hypothermia shifts the oxyhaemoglobin curve left

Hypothermia increases haemoglobin oxygen affinity. Reduced haemoglobin lowers arterial oxygen content is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Reduced baroreceptor firing increases sympathetic outflow is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Hypocapnia causes cerebral vasoconstriction 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. 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