Haldane effect — FRCA Primary MCQ

Correct answer: D — Raised PaCO2 lowers alveolar oxygen tension

Oxygenated haemoglobin carries less CO2, contributing to the Haldane effect. Left ventricular coronary perfusion occurs mainly in diastole is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Hypoxic pulmonary vasoconstriction diverts blood flow is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. High oxygen consumption and low FRC shorten safe apnoea time is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. ADH inserts aquaporin-2 channels in collecting ducts 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