1. PART 3: Breathing System Parts
A&A pgs
PART 3: Breathing System Parts
The system that brings the fresh gas from the vaporizer to the patient AND takes the expired gases from the away from the patient.
Parts: unidirectional valves, pop off valve, CO2 canister, negative pressure relief valve, pressure manometer.
Starts with the fresh gas inlet

2. Unidirectional Valves
One-way valves that allow the flow of fresh gas to only travel in one direction.
Valve is either a rigid disk or a flap that flutters as gas flows past it.
1. ____________ unidirectional valve: opens as
the patient inhales
2. ____________ unidirectional valve: opens as the patient exhales
Prevents the exhaled gases from traveling back towards the patient.

3. Unidirectional Valves
*These valves can be used to monitor respiratory rate of the patient

4. Large animal system

5. Carbon Dioxide Canister
Exhaled gases flow past the expiratory unidirectional valve and
into the CO2 canister
CO2 canisters usually contain _________ __________
granules that selectively absorb CO2 from other gases
breathed out by the patient
Examples: Soda Lime; CarbOLime

6. Carbon Dioxide Canister
If CO2 absorption is occurring:
The canister should feel warm and have moisture in it
Capnometer measurements should be WNL
The inspiratory carbon dioxide should read 0 mm Hg
Recommended to change out granules q 6-10 hours of use
VTI note: change _____________ of use
PPE is required

7. Carbon Dioxide Canister
Granules may become ___________ before ten hours!
1. Color change to violet or pink (depending on the brand).
*Most brands change _________________.
Replace granules mid-anesthesia if you have ___________ color change.
Once color changes, it is possible to change back to white-ish within hours!
2. CO2 saturated granules are hard and brittle
New ones can be chipped and crumbled with your fingers

8. Using fully exhausted granules can lead to hypercapnia in the patient
Using fully exhausted granules can lead to hypercapnia in the patient. Note: can also cause carbon monoxide poisoning when using isoflurane.

9. Pressure Manometer Unit is: ____________
Measures pressure of gas within the breathing system
This includes the patient’s lungs!
Unit is: ____________
Should read between ________________ during normal respirations
When patient is connected, gauge should never exceed:
20 cm H20 in dogs and 15 cm H20 in cats

10. Pop-off Valve - aka pressure relief valve, exhaust valve
Allows exhaled gas to leave the breathing system
This allows for a steady pressure within the system since new gas is always being added in
Always kept open
Prevents the build-up of excess gas or pressure within the circuit.
If pressure were allowed to build up (left the pop-off valve closed), the alveoli in the lungs could rupture!

11. Occlusion Valve These are safety regulated

12. Negative Pressure Release Valve aka Air Intake Valve
Special feature activated in emergencies
Indicated by no gas flow or completely empty reservoir bag
If _____________ pressure is detected in the circuit, this valve opens and allows room air in
When would this happen?
1. Instances when there is excessive __________
Ex: When an active scavenging system is utilized
2. O2 flow rate is too low or tank runs out of O2
ALWAYS keep an eye on your tank pressure gauge

13. Part 4: Scavenging System SAFTEY A&A Pg. 356
To reduce exposure to WAG
Three major types of scavenging systems:
1. Active Scavenging System
Connected to a vacuum that sucks the waste gases out of the machine…concerns?
Runs through a drop down line, through pipes in the ceiling, and outside –must be turned on!
Expensive, maintenance required

14. Scavenging System: Active

15. Scavenging System 2. Passive Scavenging System
Uses pressure in circuit to expel gases from the machine, out through a hole in the wall
Must be room adjacent to the outside

16. Scavenging System 3. Absorption Devices
Canister that contains ___________ ____________
Cheaper than installing a scavenger
Portable
Easy to use with little maintenance
Example: F/air canister

17. F/air Canister Must be discarded after 12 hours of use OR
a gain of ___________ in weight
Must weigh and label F/air canister before use!
Never occlude the bottom
Filter on the bottom must always have air flow
Down side?: do not absorb _______ ________