A patient with Child-Pugh class C cirrhosis requires emergency laparotomy. Which opioid is MOST appropriate for intraoperative analgesia given the altered pharmacokinetics?

• A Morphine, as it undergoes renal elimination unchanged
• B Codeine, as it is a prodrug requiring minimal hepatic activation
• C Remifentanil, as it is metabolised by plasma esterases independent of liver function ✓
• D Meperidine, as its active metabolite normeperidine accumulates only in renal failure

Explanation

Remifentanil is uniquely appropriate in hepatic failure because it is hydrolysed by non-specific plasma and tissue esterases (not hepatic CYP450), giving a predictable context-sensitive half-time of 3–4 minutes regardless of liver function. Morphine accumulates due to reduced first-pass and impaired glucuronidation, with its active metabolite morphine-6-glucuronide also accumulating. Meperidine's metabolite normeperidine causes seizures, and codeine requires CYP2D6-mediated hepatic O-demethylation to active morphine.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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