Background: The degradation of sevoflurane can lead to the production of compound A (CA) and carbon monoxide (CO) and an increase in temperature of the absorbent. CA is known to be nephrotoxic in rats. These reactions depend on the strong base and water contents of the carbon dioxide absorbent used. The purpose of this study was to measure the maximum amounts of CA and CO produced, and the temperature increase, for seven different carbon dioxide absorbents for sevoflurane containing different contents of strong bases. Methods: Seven absorbents [some free of strong bases (f)] were employed in hydrated (h) and completely desiccated (d) conditions in a patient model, using a circle anesthesia system connected to an artificial lung. Low-flow anesthesia with an oxygen-nitrous oxide mixture was maintained using 0.8% sevoflurane. For the quantification of CA and CO, a portable gas chromatograph was used. The temperature was measured inside the absorbent. Results: In consecutive order of CA-producing potency, Amsorb®(f)(d), Drägersorb(h), Medisorb®(h), lithium hydroxide(f)(d), Drägersorb(d), Medisorb®(d), Spherasorb®(h) and Spherasorb®(d) produced small amounts of CA. Loflosorb® and Superia®, which are free of strong bases, did not produce any CA or CO in hydrated or desiccated conditions. Only desiccated Drägersorb®, Medisorb® and Spherasorb® demonstrated small amounts of CO accompanied by a significant temperature increase. Conclusion: In this patient model, we demonstrated that different types of absorbent produced small amounts of CA and CO or none at all. No relationship could be established between temperature and CA concentration.