Factors Affecting Production of Compound A from the Interaction of Sevoflurane with Baralyme@ and Soda Lime

alkali (e.g., soda lime) convert sevoflurane to CF,==C(CF,)OCH,F, a vinyl ether called “Compound A,” whose toxicity raises concerns regarding the safe administration of sevoflurane via rebreathing circuits. In the present investigation, we measured the sevoflurane degradation and output of Compound A caused by standard (13% water) BaralymeQ brand absorbent and standard (15% water) soda lime, and Baralymea and soda lime having various water contents (including no water). We used a flow-through system, applying a gas flow rate relative to absorbent volume that roughly equaled the rate/volume found in clinical practice. Both absorbents, at similar water contents, temperatures, and sevoflurane concentrations, produced roughly equal concentrations of Compound A. Dry and nearly dry absorbents produced less Compound A early in exposure to sevoflurane, and more later, than standard absorbents.