SEVOFLURANE DEGRADATION TO COMPOUND-A IN ANESTHESIA BREATHING SYSTEMS

Determination of an effective rate constant and activation energy allo wed the application of steady-state theory to predict concentrations o f compound A from sevoflurane concentrations, fresh gas flow rate, abs orbent temperature and amount of absorbent. Studies by eight research groups were compared. Lower concentrations of compound A than predicte d were observed at low flow rates, suggesting that its degradation by the absorbent is important in limiting the maximum observed concentrat ions in closed and low-flow breathing systems. Trial-to-trial and batc h-to-batch variations in compound A concentrations were observed in mo del system tests of commercial and pilot-plant absorbents. Chemical mo dification of the absorbent with glycerol lowered concentrations of co mpound A, possibly by formation of a nucleophilic addition product. An ideal chemical scavenger would remain stable and non-volatile in the absorbent before irreversibly reacting with compound A to form a stabl e non-volatile product.