Objectives: To analyse the various methods for carbon dioxide absorption in anaesthesia, the available absorbents and their modes of use.
Data sources: We searched the Medline and Internet databases for papers using the key words: carbon dioxide absorption, soda-lime, zeolite. We also had correspondence and contacts with soda lime manufacturers.
Study selection: All types of articles containing data on CO2 absorption.
Data extraction: The articles were analysed for the benefits and adverse effects of the various absorbents.
Data synthesis: Carbon dioxide absorption enables the use of low flow anaesthesia, and a decreased consumption of medical gases and halogenated anaesthetics, as well as reduced pollution. Chemical absorbents (soda-lime and barium hydroxide lime (Baralyme) may produce toxic compounds: carbon monoxide with all halogenated anaesthetics and compound A with sevoflurane. Simple measures against desiccation of the lime prevent carbon monoxide production. The toxicity of compound A, shown in the rat, has not been proven in clinical anaesthesia. Recent improvements in manufacture processes have decreased the powdering of lime. Moreover, filters inserted between the anaesthesia circuit and the patient abolish the risk for powder inhalation.