1. CO2 combines with water to form carbonic acid. CO2 absorbents are hydroxide salts which neutralise the carbonic acid.
2. Colour conversion of a pH indicator dye (e.g., ethyl violet from white to purple) by increasing hydrogen ion concentration signals absorbent exhaustion. Absorbent should be replaced when 50% to 70% has changed colour
3. CO2 absorbants absorb (this may contribute towards delayed induction and emergence) and degrade volatile agents
4. Soda Lime and Amsorb are the commonly used CO2 absorbents
5. Soda lime consists of Ca(OH)2 [80%], NaOH, water and KOH. It is capable of absorbing up to 23 L of CO2 per 100 g of absorbent. Addition of silica decreases the danger of inhalation of NaOH dust and reduces the resistance to gas flow. The drier the soda lime, the more likely it will absorb and degrade volatile anesthetics.
6. Amsorb consists of Ca(OH)2, CaCl2, CaSO4 and polyvinylpyrrolidone to increase hardness. It is more inert towards volatile agents, so their degradation is less with Amsorb
7. The dry absorbents may break down the volatile anesthetics to carbon monoxide (CO) (e.g., sodium or potassium hydroxide). The formation of CO is highest with desflurane. Compound A is a byproduct of degradation of sevoflurane by absorbent.
Ⓜ️NEMO> CO-Des 'CODES' CoA-Sevo 'CAuSE'
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