Anesthesia machine 2 Flashcards
Identify the BEST practices for handling gas cylinders. (select 2).
a. laying the cylinder on its side when changing the cylinder on the anesthesia machine
b. oiling cylinder valves every six months
c. placing two washers between the cylinder and the hanger yoke assembly
d. removing the plastic cover on the port when installing the cylinder
a. laying the cylinder on its side when changing the cylinder on the anesthesia machine
d. removing the plastic cover on the port when installing the cylinder
____________ is the most delicate part of the cylinder.
The cylinder valve
Gas cylinders should be stored
in the upright position & secured. If you’re changing the cylinder on the anesthesia machine, it’s ok to lay the cylinder on its side temporarily
If you remove a cylinder from the anesthesia machine but you don’t have a replacement
then you’ll need to insert a yoke plug
If you open the cylinder and hear a “hissing” sound, there’s
a leak. Your first step is to tighten the connection
DO NOT _________between the cylinder and the hanger yoke assembly as this can defeat the PISS
place more than one washer
Never take a cylinder into the _______________ unless it’s made of a non-magnetic material, such as ___________
MRI scanner; aluminum
These are oxidizers:
oxygen and nitrous oxide
The fire triangle includes
an oxidizer, fuel, and igniter
Gas cylinder should never be exposed to temperatures
above 130 F or 57 C
This will increase the risk of fire and should never be done.
Do not oil the cylinder valve
You should remove ____________ from the port before installing the cylinder. Failure to do so may ____
the plastic cover; may obstruct gas flow when the cylinder is turned on
The fire triad consists of
an oxidizer, fuel, and an igniter
If there’s a fire, a _____________ built into the cylinder opens, allowing the cylinder to empty its contents in a slow and controlled way.
safety relief device
Examples of safety relief devices include
a fusible plug that melts at elevated temps- made from Wood’s metal: bismuth, lead, tin, & cadmium (BLT w/ cheese)
valve that opens at elevated pressures
frangible disk that ruptures under pressure
Who sets the standards for the required components of the anesthesia machine?
American Society for Testing and Materials (ASTM)
Who created the 1993 Anesthesia Machine Pre-Use Checkout procedures?
Food and Drug Administration (FDA)
Who sets the standards for acceptable occupational exposure to volatile anesthetics?
Occupational Safety and Health Administration (OSHA)
Who sets the standards for compressed gas cylinders?
US Department of Transportation (DOT)
A cylinder must be tested
every 5 years
The cylinder is tested for leaks and the ability to maintain structural integrity, this is done by subjecting the cylinder to
1.66 times its service pressure
What 7 items does the US DOT require on the cylinder label?
- Government agency (DOT)
- Type of metal used to construct the cylinder
- Maximum filling pressure (psi)
- Serial number
- Manufacturer
- Owner
- Date of the last inspection
The oxygen pressure failure device activates when the (Select 2):
a. oxygen pressure in the supply line is less than 20 psi
b. the oxygen pipeline contains nitrous oxide
c. FiO2 in the inspiratory limb is less than 21%
d. Oxygen tank is exhausted
a. oxygen pressure in the supply line is less than 20 psi
d. oxygen tank is exhausted
The ________ monitors for low oxygen pressure in the anesthesia machine.
oxygen pressure failure device (failsafe device)
The failsafe device will alarm in the setting of
a depleted oxygen tank
drop in pipeline pressure
disconnected oxygen hose
The failsafe device will not alarm in the setting of
an oxygen pipeline crossover (it measures oxygen pipeline pressure, not oxygen concentration)
The failsafe device resides in
the intermediate-pressure system
The failsafe device consists of:
a threshold alarm that sounds when the oxygen pipeline pressure falls below 28-30 psi
a pneumatic device that reduces or stops the flow of nitrous oxide when the pressure in the oxygen pipeline fails below 20 psi
What are the two types of oxygen pressure failure devices?
oxygen failsafe device (GE Datex-Ohmeda)
Oxygen Failure protection device (Drager)
Describe the oxygen failsafe device on the GE machine.
“all or nothing” response, if oxygen pressure >20 psi then N2O flow is allowed, if <20 psi then N2O is stopped
Describe the oxygen failure protection device on the Drager machine.
as pipeline oxygen pressure decreases, there’s a proportionate reduction of nitrous oxide flow
flow of nitrous oxide is stopped only when oxygen pressure is extremely low
Is the Failsafe system truly Failsafe?
NO!- pipeline crossover can still produce a hypoxic mixture
flowmeter leaks can also allow for a hypoxic mixture
Describe how flowmeter leaks can bypass the Failsafe system?
it’s upstream of the flowmeters, so it won’t detect a flowmeter crack where gas can escape
What is responsible for maintaining the fail-safe valve in the open position?
PRESSURE (not oxygen concentration)- which is why a pipeline crossover can get past the failsafe
How can you tell if the O2 pressure failure device is working?
- turn ON oxygen and nitrous oxide flow
- make sure oxygen cylinder is closed and then remove the source of oxygen pressure by disconnecting the pipeline
- as you remove the O2 source, observe the flowmeters, N2O flow should stop just before O2 flow stops
- Reintroducing the O2 supply to the AGM should result in both gases restored to their previous flow rates
The hypoxia prevention safety device on the anesthesia machine will:
a. shut off the flow of nitrous oxide if the oxygen supply pressure is less than 30 psi
b. limit the nitrous oxide flow to three times oxygen flow
c. alarm if the FiO2 is less than 21%
d. will prevent a hypoxic mixture if a third gas is used
b. limit the nitrous oxide flow
The ________ prevents you from setting a hypoxic mixture with the flow control valves.
hypoxia prevention safety device
When you’re administering nitrous oxide, the proportioning device ensures that the
FiO2 never drops below 25% (it maintains a max 3:1 ratio of nitrous oxide to oxygen)
What situations will the proportioning system not alarm in?
oxygen pipeline crossover
leaks distal to the flowmeter valves
administration of a third gas (e.g. helium)
defective mechanic or pneumatic components
What is another name for the hypoxia prevention safety device?
proportioning device
What are the type types of proportioning devices?
- Link 25 system (GE)
- Oxygen Ratio Monitor Controller (Drager)
How does the Link 25 system work?
the oxygen and nitrous oxide flowmeter valves are mechanically linked by a chain (mechanical component)
it incorporates a second-stage regulator for oxygen and nitrous oxide (pneumatic component)
if you try to create a hypoxic mixture, a gear engages that increases the oxygen flow automatically
How does the oxygen ratio monitor controller work?
oxygen and nitrous oxide flows are connected pneumatically
if you try to create a hypoxic mixture, the supply pressure ratio of nitrous oxide going to the flowmeter will be reduced to maintain the 3:1 ratio
Which type of flowmeter float is read at the middle?
a. skirted
b. ball
c. plumb bob
d. nonrotating
b. ball
What is another name for the traditional flowmeter?
Thorpe tube
The traditional flowmeter is the beginning of
the low-pressure system
The flowmeter controls
and measures the fresh gas flow that travels towards the vaporizers and common gas outlet
A ________ provides a constant gas pressure throughout a wide range of flow rates.
“variable orifice” architecture
Describe the internal diameter of a flowmeter.
narrowed at the base and widens along its ascent
The four types of floats include
skirted, plumb bob, nonrotating and the ball
Flow measurement is taken at the top of the float for these types of floats:
skirted, plumb bob, nonrotating
A flowmeter leak can
create a hypoxic mixture- problematic because the flowmeters are distal to all the safety devices
To minimize the risk of a hypoxic mixture in the setting of a cracked flowmeter, the O2 flowmeter should
be positioned closest to the common gas outlet (on the far right on U.S. machines)
Reynols’ number tells us
what type of flow we have
laminar, turbulent, and transitional
Laminar flow is
<2000
Turbulent flow is
> 4000
Transitional flow is
2000-4000
The position of the indicator float is determined by these two opposing forces:
FGF pushes the indicator float up
gravity pulls the indicator float down
What is the annular space of the flowmeter design?
area between the float and sidewall of the flowmeter
How is Reynolds’ number calculated?
Density x diameter x velocity/ viscosity
