During low-flow anaesthesia with sevoflurane at fresh gas flow of 1 L/min using soda lime, Compound B accumulates in the circuit. Which clinical feature directly results from prolonged inhalation of high concentrations of Compound B?

• A Hepatocellular necrosis
• B Bronchospasm
• C Methemoglobinaemia
• D Renal proximal tubular injury ✓

Explanation

Compound B (fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether) is nephrotoxic; it generates inorganic fluoride and reactive olefins in renal tubular cells causing proximal tubular necrosis in animal models. Clinical significance in humans remains debated, but guidelines recommend avoiding ultra-low flows (<1 L/min) with sevoflurane when using desiccated absorbents. Hepatotoxicity and methemoglobinaemia are not associated with Compound B. Carbon monoxide from desiccated absorbent reacts with desflurane/isoflurane more than sevoflurane.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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