[Differential reactivities of three kinds of carbon dioxide absorbents with high concentration of sevoflurane].

The differential reactivities of three kinds of carbon dioxide absorbents, sodalime, Sodalime A and Baralyme with 5% sevoflurane were investigated in a closed system under administration of 5% carbon dioxide. The degradation products in the closed system were determined by gas chromatography and the temperature of the glass container which was filled with each carbon dioxide absorbent was monitored. The degradation products, P1, P3 and P5 were produced by every carbon dioxide absorbents even after one-hour circulation. Especially P3 and P5 were produced by Baralyme more than the others after two or four-hour circulation. The significant differences of the temperature among glass containers were not recognized. Previously we found that the reactivity of Sodalime A is the highest among the three kinds of carbon dioxide absorbents when low concentration of sevoflurane (2 or 3%) is used. Possible explanation for this result is that the increasing temperature of glass container filled with each carbon dioxide absorbent is different from each other, and Sodalime A is the highest. The reactivity was thought to depend on the temperature of glass container. However, with this high concentration of sevoflurane (5%), Baralyme has the highest reactivity. Baralyme contains higher proportion of KOH which has the highest reactivity with sevoflurane than the other constituents of carbon dioxide absorbents. The reactivity of sodalime, Sodalime A and Baralyme with 5% sevoflurane was thought to depend not on their temperature but on their chemical constitutions. These results suggested that the using high concentration sevoflurane with Baralyme should be reconsidered.