US Patent 7476641 Chemical absorbent

A chemical absorbent comprises a hydrated mixture of a major proportion of a pharmaceutically acceptable hydroxide of a Group II metal and a minor proportion of silica, the chemical absorbent being substantially free of Group I metal ions. The chemical absorbent is particularly useful in low flow or closed circuit anaesthesia, and is advantageous in that it does not react with volatile anaesthetic agents in such a way as to cause the build up of toxic substances within an anaesthetic breathing circuit.