Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of compound A from sevoflurane in clinical practice

We investigated the concentrations of degraded sevoflurane Compound A durin g low-flow anesthesia with four carbon dioxide (CO2) absorbents. The concen trations of Compound A, obtained from the inspiratory limb of the circle sy stem, were measured by using a gas chromatograph. In the groups administere d 2 L/min fresh gas flow with 1% sevoflurane, when the conventional CO2 abs orbents, Wakolime(TM) (Wako, Tokyo, Japan) and Dragersorb(TM) (Drager, Lube ck, Germany), were used, the concentrations of Compound A increased steadil y from a baseline to 14.3 ppm (mean) and 13.2 ppm, respectively, at 2 h aft er exposure to sevoflurane. In contrast, when the other novel types of abso rbents containing decreased or no potassium hydroxide/sodium hydroxide, Med isorb(TM) (Datex-Ohmeda, Louisville, CO) and Amsorb(TM) (Armstrong, Colerai ne, Northern Ireland), were used, Compound A remained at baseline (<2 ppm) throughout the study. In the groups administered 1 L/min fresh gas now with 2% sevoflurane, Wakolime(TM) and Dragersorb(TM) produced much larger conce ntrations of Compound A (35.4 ppm and 34.2 ppm, respectively) at 2 h after exposure to sevoflurane. Medisorb(TM) showed measurable concentrations of C ompound A (8.6 ppm at 2 h), but they were significantly smaller than those produced by the two conventional absorbents. In contrast, when Amsorb(TM) w as used, Compound A concentrations remained at baseline throughout the stud y period.