Week 8 CO2 absorption Flashcards
Why is granule hardness important? How is it tested? What should the hardness number be?
- excessive powder → channeling, resistance, caking
- tested with steel ball bearings & screen pan
- % of original remaining = hardness number
- hardness number should be >75
Describe the gas flow through the CO2 absorber during the inhalation phase of respiration.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/316/980/964/a_image_thumb.jpeg?1595821579)
What is the absorptive capacity of baralyme?
26 liters of CO2 per 100 grams absorbent granules
In CO2 absorbers, color conversion signals….
absorber exhaustion
Describe how Compound A can be a problem with CO2 absorbents. What do you manufacturers recommend related to this issue? How do practitioners avoid this problem?
- CO2 granules degrade volatile anesthetic agents to some extent, especially sevoflurane
- when degraded by a strong base in CO2 absorbents (containing KOH and to a lesser extent, NaOH), sevoflurane forms Compound A at concentrations which have been demonstrated to be nephrotoxic in rats
- does not appear to be an issue with absorbents with no KOH/NaOH
- Manufacturer recommens no more than 2 MAC hours at flow rates of 1 to <2 L/min
- MAC hours = MAC x hours of inhalation agent given
- 1 MAC x 2 hours = 2 MAC hours
- 1/2 MAC x 4 hours = 2 MAC hours
- MAC hours = MAC x hours of inhalation agent given
- Most practitioners use at least 2 liters of FGF with sevo
- although this practice is not evidenced based necessarily no connection between renal damage and sevoflurane use has been determined after extensie clinical use
- ALSO, new absorbents do not appear to form Compound A
- although this practice is not evidenced based necessarily no connection between renal damage and sevoflurane use has been determined after extensie clinical use
Describe the calcium hydroxide reaction.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/316/974/823/a_image_thumb.jpeg?1595814344)
Describe the soda lime reaction.
- carbon dioxide combines with water to form carbonic acid
- carbonic acid reacts with hydroxides to form sodium (or potassium) carbonate and water and heat
![](https://s3.amazonaws.com/brainscape-prod/system/cm/316/974/347/a_image_thumb.jpeg?1595813855)
Which volatile anesthetic is associated with the highest accumulation of carbon monoxide?
desflurane
How many liters of CO2 are 100g soda lime capable of absorbing?
26 liters of CO2/100 g of absorbent granules
What is channeling? Why is it a problem? How do some manufacturers try to prevent?
-
preferential passage of exhaled gas flow through absorber via pathways of low resistance
- results from loosely packed granules
- air space occupies 48-55% of the volume of the canister
- absorbent along channels may exhaust
- CO2 may filter though channels not visible
- CO2 monitoring may be affected
- some manufacturers now use a polymer to bind the granules in pre - formed channels to prevent channeling
What is the composition of Baralyme?
- 80% calcium hydroxide
- 20% barium hydroxide
- small amounts of sodium hydroxide and potassium hydroxide may be added
- (no hardening agent)
- (no water)
- granules are 4-8 mesh
What is the makeup of calcium hydroxide lime (aka amsorb plus)?
- 80% calcium hydroxide
- 16% water
- 1-4% calcium chloride
- calcium sulfate and polyvinylpyrrolidine
- added hardness
T or F: Color of the absorbent can revert back with rest.
True;
**especially in NaOH containing formulations**
1 pound of lithium hydroxide absorbs how many pounds of carbon dioxide?
.91 pounds of carbon dioxide
Desribe the litholyme reaction.
end product: lithium carbonate, water, heat
![](https://s3.amazonaws.com/brainscape-prod/system/cm/316/976/015/a_image_thumb.jpeg?1595815302)