title: Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of compound A from sevoflurane in clinical practice.
abstract: We investigated the concentrations of degraded sevoflurane Compound A during low-flow anesthesia with four carbon dioxide (CO(2)) absorbents. The concentrations of Compound A, obtained from the inspiratory limb of the circle system, were measured by using a gas chromatograph. In the groups administered 2 L/min fresh gas flow with 1% sevoflurane, when the conventional CO(2) absorbents, Wakolime(TM) (Wako, Tokyo, Japan) and Drägersorb(TM) (Dräger, Lübeck, Germany), were used, the concentrations of Compound A increased steadily from a baseline to 14.3 ppm (mean) and 13.2 ppm, respectively, at 2 h after exposure to sevoflurane. In contrast, when the other novel types of absorbents containing decreased or no potassium hydroxide/sodium hydroxide, Medisorb(TM) (Datex-Ohmeda, Louisville, CO) and Amsorb(TM) (Armstrong, Coleraine, Northern Ireland), were used, Compound A remained at baseline (<2 ppm) throughout the study. In the groups administered 1 L/min fresh gas flow with 2% sevoflurane, Wakolime(TM) and Drägersorb(TM) produced much larger concentrations of Compound A (35.4 ppm and 34.2 ppm, respectively) at 2 h after exposure to sevoflurane. Medisorb(TM) showed measurable concentrations of Compound 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) was used, Compound A concentrations remained at baseline throughout the study period.
  
  
  CONCLUSIONS
  Carbon dioxide absorbents containing potassium hydroxide/sodium hydroxide produce much larger concentrations of Compound A from sevoflurane in clinical practice. An absorbent containing neither potassium hydroxide nor sodium hydroxide produces the smallest concentrations of Compound A.
authors.affiliation: Department of Anesthesiology, Sapporo Medical University School of Medicine, Japan. yamakage@sapmed.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Yamakage
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Iwasaki
authors.forename: N
authors.initials: N
authors.lastname: Tsujiguchi
authors.forename: A
authors.initials: A
authors.lastname: Namiki
mesh_terms: D000042:Absorption; D000768:Anesthesia, General / Q000295:instrumentation; D018685:Anesthetics, Inhalation / Q000737:chemistry; D002245:Carbon Dioxide; D002849:Chromatography, Gas; D004987:Ethers / Q000032:analysis*; D005260:Female; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000032:analysis*; D006878:Hydroxides / Q000737:chemistry; D008297:Male; D008738:Methyl Ethers / Q000737:chemistry; D008875:Middle Aged; D017680:Potassium Compounds / Q000737:chemistry; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D004987:Ethers; D006845:Hydrocarbons, Fluorinated; D006878:Hydroxides; D008738:Methyl Ethers; D017680:Potassium Compounds; D002245:Carbon Dioxide; D000077149:Sevoflurane; C078742:fluoromethyl 2,2-difluoro-1-(trifluoromethyl)vinyl ether; C029943:potassium hydroxide