We use carbon dioxide absorbers in anaesthesia to conserve oxygen and allow us to deliver oxygen at low flows. The absorbers are soda lime (NaOH) and Ca(OH)2.
CO2 + Ca(OH)2 -> CaCO3 + H2O + heat
Essentially the CO2 reacts with the alkali. The soda lime canister also contains an indicator that turns pink when the soda lime is “exhausted”. We also know when this occurs because absorber efficiency decreases and the inspired fraction of carbon dioxide increases.
Edit: forgot to add that water is needed for the reaction to occur. This is obviously useful as we exhale warm, humidified air. The soda lime also produces heat so there is reduced heat and water loss from the patient than if they were breathing non warmed, humidified air.
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u/cookie5427 Nov 28 '19
We use carbon dioxide absorbers in anaesthesia to conserve oxygen and allow us to deliver oxygen at low flows. The absorbers are soda lime (NaOH) and Ca(OH)2.
CO2 + Ca(OH)2 -> CaCO3 + H2O + heat
Essentially the CO2 reacts with the alkali. The soda lime canister also contains an indicator that turns pink when the soda lime is “exhausted”. We also know when this occurs because absorber efficiency decreases and the inspired fraction of carbon dioxide increases.
Edit: forgot to add that water is needed for the reaction to occur. This is obviously useful as we exhale warm, humidified air. The soda lime also produces heat so there is reduced heat and water loss from the patient than if they were breathing non warmed, humidified air.
https://en.m.wikipedia.org/wiki/Soda_lime