[Reactivity of sevoflurane with carbon dioxide absorbents--comparison of soda lime and Baralyme].

The reactivity of sevoflurane with carbon dioxide absorbents, soda lime and Baralyme which are commercially available carbon dioxide absorbents, was studied. A closed circuit system which was made only for this investigation was set up without rubber. Sevoflurane 5% was circulated for 17 hours. The circulated gas was analyzed by gas chromatography (GC) and degradation products were identified by a gas chromatography-mass spectroscopy (GC-MS) as fluoromethyl 2-methoxy-2, 2-difluoro-1-(trifluoromethyl) ethyl ether, fluoromethyl 2-methoxy-2-fluoro-1-(trifluoromethyl) vinyl ether, and its isomer. These degradation products of sevoflurane from soda lime and Baralyme were the same substances. The rate of degradation by soda lime was 0.88% +/- 0.306, while that by Baralyme was 3.40% +/- 0.501. Baralyme decomposed sevoflurane about four times more than soda lime. There are two possible explanations for these results. One is the Baralyme contains more potassium hydroxide than soda lime. The other is that soda lime absorbs sevoflurane more because it contains more silica.