CO2 Absorber Flashcards
Carbon dioxide absorber
- chemically neutralizes CO2
- contains a base that neutralizes acid
- acid = carbonic acid
- base = hydroxide of alkali or alkaline earth metal (NaOH, KOH, CaOH)
- end product = water + carbonate + heat
What are some advantages and disadvantages to CO2 absorbers
- conserve heat/humidity
- conserve anesthestic gases
- can get exhausted and need to be changed frequently
- become dessicated and you dont know it
Name 4 types of CO2 absorbants
- Potassium hydroxide Lyme (soda lime)
- Calcium hydroxide Lyme (amsorb plus)
- Baralyme
- Litholyme
What are the components that make up Soda Lyme?
- 4% sodium hydroxide
- 1% potassium hydroxide
- 0.2% silica (prevents dust)
- 15% water
- 80% calcium hydroxide
How much CO2 can Soda Lime absorb
-26L of CO2 / 100g of absorbent granules
-How much CO2 does CaOH2 absorb?
1lb of CaOH2 can absorb 0.59lbs of CO2
Soda Lime Reaction
- CO2 —> H2O = H2CO3
- H2CO3 —> NaOH = NaCO3 + H2O + heat
- H2CO3 —> KOH = KCO3 + H2O + heat
- NaCO3 —> CaOH = Ca3(CO3)2 NaOH
What are the components that make up Amsorb?
- 80% calcium hydroxide
- 16% water
- 1-4% calcium chloride (moisturizer)
- calcium sulfate and polyvinylpyrrolidine added harshness
How much CO2 can Amsorb absorb?
- capable of absorbing 10L of CO2 / 100g of granules
Calcium hydroxide reaction
- CO2 —> H2O = H2CO3
2. H2CO3 —> CaOH2 = CaCO3 + 2H20 + heat
What are the advantages and disadvantages of Amsorb?
- Advantages: doesn’t create carbon monoxide or compound A and there is low fire risk
- Disadvantages: must be changed out more frequently, less CO2 absorbed than soda lime, more expensive
What are the components of BaraLyme
20% BaOH 80% CaOH *small amounts of KOH and NaOH may be added* -mesh size 4-8 -no hardening agent added -no water
How much CO2 can Soda Lime absorb
-26 L CO2 / 100g of granules
What are the components of Litholyme
-75% lithium hydroxide
-12-19% H2O
<3% lithium chloride
How much CO2 does Litholyme absorb?
-1lb of LiOH absorbs 0.9 lbs of CO2
CO2 absorber exhaustion
- when the pH level falls below 10.3 the absorber turns ethyl violet
- when not in use it will go back to white
- these should be replaced at 50-70% exhaustion
- *increasing MV does not help if you are rebreathing
- *increase FGF while you change CO2 absorber
Mesh size
- size 4-8; determines which granules can go through
- irregular granules have larger surface area
- small granules have increased surface area and resistance
- larger granules have smaller surface area and resistance
Granule hardness
—
Channeling
- the preferential flow of gas exhaled into the CO2 absorber through channels that result of loosely packed particles
- these channels can become exhausted and might not be visible from the outside
- this may affect CO2 monitoring but not show visual indications of exhaustion
- air space = 48-55% of the volume of the canister
- some manufacturers now use polymers to bind granules in pre-formed channels to prevent channeling
Describe Compound A formation in CO2 absorbers
- created when sevoflurane is degraded by a strong base in carbon dioxide absorbents containing KOH and to a lesser extent NaOH
- has been found to be nephrotoxic in rats
MAC hour recommendation and compound A
-
Describe Carbon Monoxide formation in CO2 absorbers
- CO has been known to develop from the volatile anesthetic in desiccated NaOH and KOH containing aborbers when:
- high flow is used through a system for a prolonged period of time
- when the system is not in use for 24-48 hours (Monday)
- this results in critical levels of carboxyhemoglobin
Which anesthetic has been known to produce the highest amount of CO2
-Desflurane
Which absorber is associated with fires?
-Baralyme
