A patient with Child-Pugh class C cirrhosis requires emergency bowel resection. Which of the following physiological derangements most directly prolongs the action of induction agents such as propofol and thiopentone?
- A Increased cardiac output from hyperdynamic circulation
- B Reduced first-pass metabolism due to portosystemic shunting
- C Reduced hepatic synthesis of plasma proteins decreasing drug binding ✓
- D Metabolic acidosis increasing ionised drug fraction
Correct answer: C. Reduced hepatic synthesis of plasma proteins decreasing drug binding
Explanation
Severe hepatic disease reduces albumin and alpha-1 acid glycoprotein synthesis; drugs that are highly protein-bound (e.g., thiopentone ~80%) have a greater free fraction, producing enhanced and prolonged effect at standard doses. Portosystemic shunting mainly affects orally administered drugs via first-pass; IV drugs are less affected by shunting. A hyperdynamic circulation can increase volume of distribution but the free-fraction effect from hypoalbuminaemia is the primary pharmacokinetic concern with IV agents.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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