Carbon monoxide production from desflurane and six types of carbon dioxide absorbents in a patient model

BACKGROUND: Desflurane is known to produce high concentrations of carbon monoxide (CO) in desiccated sodalime or Baralyme (Allied Healthcare Products, St. Louis, MO). Desiccated absorbents without strong bases like potassium hydroxide or sodium hydroxide are reported to produce less or no CO at all. The purpose of this study is to compare the concentration of CO in an anesthesia circuit for desflurane with six different types of completely desiccated CO(2) absorbents with less strong bases than sodalime. METHODS: A patient model was simulated using a circle anesthesia system connected to an artificial lung. Completely desiccated CO(2) absorbent (950 g) was used in this system. A low flow anesthesia (500 ml min(-1)) was maintained using desflurane. For immediate quantification of CO production a portable gas chromatograph was used. RESULTS: Peak concentrations of CO were very high in Medisorb (Datex-Ohmeda, Hoevelaken, The Netherlands) and Spherasorb (Intersurgical, Uden, The Netherlands) (13317 and 9045 p.p.m., respectively). It was lower with Loflosorb (Intersurgical, Uden, The Netherlands) and Superia (Datex-Ohmeda, Hoevelaken, The Netherlands) (524 and 31 p.p.m., respectively). Amsorb (Armstrong, Coleraine, N. Ireland) and lithium hydroxide produced no CO at all. CONCLUSION: Medisorb and Spherasorb are capable of producing large concentrations of CO when desiccated. Loflosorb and Superia produce far less CO under the same conditions. Amsorb and lithium hydroxide should be considered safe when desiccated.