Anesthesia Machine Flashcards
The high pressure system begins at ______ and ends at _______
the cylinder
the cylinder regulator
The intermediate pressure system begins at ______ and ends at ________
pipeline
flowmeter VALVES
The low pressure system begins at ______ and ends at ________
Flowmeter TUBES
Common gas outlet
What does the low pressure leak test assess?
Integrity of the circuit from the flowmeters to the CGO. Requires the bulb.
What does the high pressure leak test assess?
The low pressure system AND the breathing circuit
The vaporizers are in the _______ system
low pressure
What are the five tasks of oxygen?
- O2 pressure alarm
- O2 failure device
- O2 flowmeter
- O2 flush
- Ventilator Drive Gas
What is the PISS configuration for air?
1,5
What is the PISS configuration for O2?
2, 5
What is the PISS configuration for N2O?
3,5
What is the service pressure in a nitrous tank?
745 psi
What is the service pressure in an air tank?
1900 psi
What is the service pressure in an O2 tank?
1900 psi
What is the max volume of O2 in a tank?
660 L
What is the max volume of air in a tank?
625 L
What is the max volume of nitrous in a tank?
1590 L
How do you calculate the amount of nitrous left in a tank from the PSI?
You can’t. You have to weigh it.
What are O2 tank safety relief valves?
Allow the cylinder to slowly empty its contents if it’s exposed to extreme temperatures
What are some examples of O2 safety relief valves?
Wood’s metal:
Bismuth
Lead
Tin
Cadmium
(BLT with Cheese)
The oxygen pressure failure device activates when:
Supply line pressure is less than 20 psi
The oxygen fail safe device resides in the _______ system
intermediate
The oxygen failsafe device does two things:
- Alarms when O2 pressure falls below 20 psi
- Shuts off Nitrous flow when O2 pressure falls below 20 psi
There are two times when an O2 failsafe device will allow a hypoxic mixture:
- Oxygen pipeline crossover
- Flowmeter Leak (it’s upstream from the flowmeter, so it won’t detect if oxygen is leaking out there)
What is the hypoxia prevention safety device?
This is the one that automatically reduces nitrous when O2 is reduced.
Keeps a 3:1 ratio of nitrous to oxygen
When will the hypoxia prevention safety device fail to alarm?
- Pipeline crossover
- Leak DISTAL to the flowmeter VALVES
- Administration of a third gas (helium)
- Defective pneumatic parts
What’s the difference between the oxygen pressure failure device and the hypoxia prevention safety device?
Which type of flowmeter float is read in the middle?
The ball
All the others are read at the top
A traditional flowmeter is also known as:
a Thorpe tube
The internal diameter of a thorpe tube is:
Narrowest at the base, and widens along its ascent
What is the annular space in a flowmeter?
The area between the float and side wall of the tube
How does low vs. high flow through a flowmeter impact flow dynamics?
The O2 flowmeter should be positioned:
Closest to the manifold outlet. In the US, this is on the far right
What’s the calculation for FiO2 using air and O2?
How do you calculate FiO2 with a nasal cannula?
The first liter is 3%
What is “fresh gas coupling”
When fresh gas flow is added to the set tidal volume administered, so the actual Vt i
What is the calculation for Vt with fresh gas coupling?
In machines that couple fresh gas flow, what vent changes will INCREASE Vt?
In machines that couple fresh gas flow, what vent changes will DECREASE Vt?
How do you calculate the volume lost to circuit compliance?
The compliance of the circuit x the peak pressure, then subtract that amount from the Vt
How does elevation effect desflurane vaporizer settings?
Where does the oxygen analyzer reside?
The inspiratory limb of the breathing circuit
How do galvanic fuel cell oxygen analyzers work?
How do paramagnetic oxygen analyzers work?
What should you do when the oxygen analyzer alarm goes off?
ASSUME THERE IS A PIPELINE CROSSOVER
Disconnect the pipeline and open the O2 tank
Pressing the O2 flush valve exposes the circuit to a flow of _________
35-75 L/min
Pressing the O2 flush valves exposes the circuit to a pressure of __________
Pipeline pressure…
~ 50 psi
What two functions does the drive gas perform in a pneumatic ventilator?
- Compresses the bellows
- Opens and closes the ventilator spill valve
What is the position of the ventilator spill valve during inspiration?
Closed
Ensures the tidal volume goes to the patient and not the scavenging system
What are two complications caused by overuse of the O2 flush valve?
Barotrauma
Awakening
Why are ascending bellows considered safer?
Because descending bellows continue to rise and fall even if there is a circuit disconnect
A leak in the bellows can cause:
Barotrauma
A decrease in inspired anesthetic concentration
What are the benefits of using calcium hydroxide rather than soda lime?
No CO production
No Compound A production
Lower fire risk
What are the drawbacks to using calcium hydroxide?
Lower absorption capacity
More frequent replacement
Higher cost
According to OSHA, nitrous oxide levels in the air should be less than:
25 ppm when administered alone
According to OSHA, halogenated anesthetic levels should be less than:
2ppm if administered alone
0.5ppm if administered with nitrous oxide
