Warfarin factor half-life — FRCA Primary MCQ

Correct answer: B — Aldosterone increases sodium reabsorption and potassium secretion

Factor VII falls early because it has a short half-life among vitamin K-dependent factors. Citrate binds ionised calcium is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Right ventricular afterload rises with pulmonary vascular resistance 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. Renin rises with reduced afferent arteriolar pressure 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