Important role of calcium chloride in preventing carbon monoxide generation during desflurane degradation with alkali hydroxide-free carbon dioxide absorbents.

We investigated whether calcium chloride (CaCl2), a supplementary additive in carbon dioxide (CO2) absorbents, could affect carbon monoxide (CO) production caused by desflurane degradation, using a Japanese alkali-free CO2 absorbent Yabashi Lime®-f (YL-f), its CaCl2-free and 1% CaCl2-added derivatives, and other commercially available alkali-free absorbents with or without CaCl2. The reaction between 1 L of desflurane gas (3-10%) and 20 g of desiccated specimen was performed in an artificial closed-circuit anesthesia system for 3 min at 20 or 40 °C. The CO concentration was measured using a gas chromatograph equipped with a semiconductor sensor detector. The systems were validated by detecting dose-dependent CO production with an alkali hydroxide-containing CO2 absorbent, Sodasorb®. Compared with YL-f, the CaCl2-free derivative caused the production of significantly more CO, while the 1% CaCl2-added derivative caused the production of a comparable amount of CO. These phenomena were confirmed using commercially available absorbents AMSORB® PLUS, an alkali-free absorbent with CaCl2, and LoFloSorb™, an alkali-free absorbent without CaCl2. These results suggest that CaCl2 plays an important role in preventing CO generation caused by desflurane degradation with alkali hydroxide-free CO2 absorbents like YL-f.