Soda lime (carbon dioxide absorbent) reacts with certain volatile anaesthetics to produce toxic compounds. Specifically, sevoflurane reacts with desiccated soda lime to produce which toxic compound?

• A Carbon monoxide (CO)
• B Hydrogen fluoride
• C Formaldehyde
• D Compound A (fluoromethyl-2,2-difluoro-1-(trifluoromethyl)vinyl ether) ✓

Explanation

Sevoflurane undergoes degradation by soda lime (particularly when desiccated) to produce Compound A, a nephrotoxic vinyl ether. Normal (hydrated) soda lime generates Compound A in amounts generally below toxicity thresholds in humans. Desiccated baralyme produces higher concentrations. The FDA recommends minimum FGF of 2 L/min for sevoflurane with soda lime. Desflurane and isoflurane react with desiccated strong base absorbents to produce carbon monoxide (CO); sevoflurane does not produce CO but does produce Compound A.

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

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