Anesthesia machine Flashcards
You are administering air 1 L/min and oxygen 3 L/min. Calculate the fraction of inspired oxygen.
80%
Describe the fiO2 calculation.
When using a flowmeter: FIO2= [Air flow rate x 21] + (Oxygen flow rate x 100)]/total flow rate
Describe how to calculate fiO2 with nasal cannula.
add 4% fIo2 for every liter of O2 administered up to a maximum of 44% FiO2 at 6 L/min.
Identify the components of the low-pressure system in the anesthesia machine. (Select 2).
a. flowmeter tubes
b. oxygen flush valve
c. common gas outlet
d. Cylinder pressure regulator
a flowmeter tubes
c. common gas outlet
The anesthesia machine can be divided into the
high-, intermediate, and low-pressure systems
The high-pressure system begins at ____________ and ends at _____________
the cylinder and ends at the cylinder regulators
The intermediate pressure system begins at _______________ and ends at ______________
the pipeline and ends at the flowmeter vavles
The low pressure system begins at _______ and ends at ____________
the flowmeter tubes and ends at the common gas outlet
The low pressure leak test assesses the
integrity of the low-pressure circuit from the flowmeter valves to the common gas outlet
Describe how to perform a low pressure leak test.
The test is performed by attaching a bulb to the common gas outlet and creating negative pressure. It must be performed with the vaporizers off, and then again with each vaporizer turned on one at a time
if the bulb inflates there’s a leak in the system
Describe how to perform a low pressure leak test.
The test is performed by attaching a bulb to the common gas outlet and creating negative pressure. It must be performed with the vaporizers off, and then again with each vaporizer turned on one at a time
if the bulb inflates there’s a leak in the system
The high-pressure leak test assesses the integrity
of the low-pressure system and the breathing circuit
Describe how to perform the high-pressure leak test.
this test is performed by closing the APL valve, pressurizing the circuit to 30 cm H2O and observing the airway pressure gauge
Describe how to perform the high-pressure leak test.
this test is performed by closing the APL valve, pressurizing the circuit to 30 cm H2O and observing the airway pressure gauge
if the pressure doesn’t stay ~30 cm H2O, there’s a leak in the system
Describe the components of the high-pressure system.
hanger yoke
yoke bloke with check valves
cylinder pressure gauge
cylinder pressure regulators
Describe the components of the intermediate-pressure system.
pipeline inlets
pressure gauges
oxygen pressure failure device
oxygen second stage regulator
oxygen flush valve
ventilator power inlet
flowmeter valves
Describe the components of the low-pressure system.
flowmeter tubes (Thorpe tubes)
vaporizers
check valve (if present)
common gas outlet
What is the SPDD model?
it is an alternative way to describe the architecture of the anesthesia machine
comprised of supply, processing, delivery, and disposal
The five tasks of oxygen in the SPDD model include:
O2 pressure alarm
O2 pressure failure device
O2 flowmeter
O2 flush valve
Ventilator drive gas
Describe the supply phase of the SPDD model.
How the gases enter the anesthesia machine
The location of the supply phase of the SPDD model is
the pipeline to the back of an anesthesia machine
Describe the processing phase of the SPDD model.
how the anesthesia machine prepares the gases before they are delivered to the patient
What is the location of the processing phase of the SPDD model?
inside the machine up to the common gas outlet
Describe the delivery phase of the SPDD model.
how the prepared gases are brought to the patient
What is the location of the delivery phase of the SPDD model?
breathing circuit
Describe the disposal phase of the SPDD model.
how the gases are removed from the breathing circuit
What is the location of the disposal phase of the SPDD model?
scavenging system
The PISS system is used to:
a. prevent the use of the wrong gas hose
b. prevent the use of the wrong gas cylinder
c. diagram the pathway of gas through the anesthesia machine
d. filter and exchange air in the operating room
B. prevent the use of the wrong gas cylinder
The PISS stands for
Pin index safety system
The PISS is used to
prevent inadvertent misconnections of gas cylinders
What is the PISS configuration for air?
1, 5
What is the PISS configuration for oxygen?
2, 5
What is the PISS configuration for nitrous oxide?
3, 5
The DISS stands for
diameter index safety system
The DISS prevents
inadvertent misconnections of gas hoses (each gas hose and connector are sized and threaded for each gas)
The presence of more than one washer between the hanger yoke assembly and the stem of the tank
may allow the PISS to be bypassed
The pressure change that occurs at the gas hoses is
50 psi
The bourdon pressure gauge on an oxygen cylinder reads 500 psi. If the flow rate is 2 L/min, how long will this cylinder provide oxygen to the patient?
75 minutes
The oxygen cylinder on the back of the anesthesia machine must be
turned OFF when not in use; if not, you may use the cylinder oxygen without knowing it
What is the service pressure and maximum volume for air?
1900 psi
625 L
What is the pressure and maximum volume for oxygen?
1900 psi
660 L
What is the pressure and maximum volume for nitrous oxide?
745 psi
1590 L
Nitrous oxide exists as
a liquid inside the cylinder (unless it’s almost empty), because its critical temperature is above room temperature (36.5 C)
Describe how to calculate how much O2 is left in a cylinder.
660 / 1900 Psi X contents remaining (L)/ 500 psi (or whatever # they supply you with)
then you will take contents remaining/ L/min to get how many minutes left before the tank expires
When should you change the nitrous oxide tank?
whenever it falls below 745 psi b/c the pressure will only decrease when all the liquid is consumed and at this point it would be 3/4 empty
The only reliable method to determine the volume of nitrous oxide that remains in the tank is
to weigh it
What is the maximum volume and pressure of carbon dioxide?
volume: 1590 L
pressure: 838 psi
