Anesthesia Machine Flashcards
These are part of the (low/int/high system)?
Common gas outlet
Thorpe tubes
Vaporizers
Low pressure system
These are part of the (low/int/high system)?
Flowmeter valves
Oxygen flush valve
Oxygen pressure failure device
Pipeline inlets
Intermediate Pressure System
These are part of the (low/int/high system)?
Hanger yoke
Cylinder pressure regulator
Cylinder pressure gauge
High Pressure System
How is a low-pressure leak test performed?
This test is performed by attaching a bulb to the common gas outlet and creating negative pressure. Failure occurs if the bulb reinflates within 10 seconds.
How much negative pressure should be created for a proper negative-pressure test?
– 65 cm H2O
Should the vaporizer be on or off during a low-pressure leak test?
Both on and off. The vaporizers should be off at first, but then the test should be repeated with vaporizer turned on.
List the 4 components of the SPDD model.
Supply
Processing
Delivery
Disposal
The PISS system is used to:
prevents the wrong cylinder from being attached to the anesthesia machine.
The DISS system is used to:
prevents the wrong gas hose from being attached to the anesthesia machine.
What is the pin configuration for oxygen
2, 5
What is the pin configuration for air
1, 5
What is the pin configuration for N2O
3, 5
What is the maximum volume of an O2 cylinder?
660 L
What is the maximum volume of an air cylinder?
625 L
What is the maximum volume of an N2O cylinder?
1, 590 L
What is the maximum pressure inside an O2 cylinder?
1,900 psi
What is the maximum pressure inside an air cylinder?
1,900 psi
What is the maximum pressure inside an N2O cylinder?
745 psi
Can an cylinder be laid on its side while being changed?
Yes, only when empty and being changed out
What agency sets the standards for the required components of the anesthesia machine.
American Society for Testing and Materials (ASTM)
What agency developed the Anesthesia Machine Pre-Use Checkout procedures.
Food and Drug Administration (FDA)
What agency sets the standards for acceptable occupational exposure to volatile anesthetics.
Occupational Safety and Health Administration (OSHA)
What agency sets the requirements for compressed gas cylinders.
United States Department of Transportation (DOT)
The oxygen pressure failure device activates when the (2)
oxygen pressure in the supply line < 20 psi and O2 tank exhaustion
What is the purpose of the oxygen failsafe device?
To monitor for (and protect against) low oxygen pressure in the anesthesia machine.
The oxygen failsafe device will alert you to what 3 problems?
Depleted O2 tank
A drop in pipeline pressure
Disconnected O2 supply hose
In what pressure system does the oxygen failsafe device reside?
Intermediate pressure system
When does the oxygen failsafe device fail to detect a hypoxic mixture?
(2)
Oxygen-Pipeline Crossover
Flowmeter Leak
What is another name for the oxygen failsafe device?
Oxygen pressure failure device
The hypoxia prevention safety device on the anesthesia machine will:
limit the nitrous oxide flow to three times oxygen flow.
What is another name for the proportion device?
Hypoxia prevention safety device
What is the minimum FiO2 permitted by the proportioning device?
25%
How does the proportioning device work?
It limits N2O flow to 3 times O2 flow (N2O max ~ 75%)
Which type of flowmeter float is read at the middle?
Ball
How are the skirted, plumb bob, and nonrotating floats read?
at the top of the float.
What is the annular space?
The area between the float and sidewall of the flowmeter.
(ball float)
Describe the internal geometry of the flowmeter.
The flowmeter is narrowest at the base and widens along its ascent. This creates a “variable orifice” architecture.
What is the safest position for the oxygen flowmeter as it relates to other gas flowmeters?
Positioned on the far right (closest to the manifold outlet)
These things (increase/decrease tidal volume)
Increased I:E ratio
Increased bellows height
Decreased respiratory rate
Increased gas flow
Increases Tidal Volume
These things (increase/decrease tidal volume)
Decreased gas flow
Decreased bellows height
Increased respiratory rate
Change the I:E ratio from 1:2 to 1:3
Decreases Tidal Volume
How does circuit compliance affect the tidal volume delivered to the patient?
If it is not compensated for, the tidal volume will decrease. Some machines automatically compensate.
What should you do if the vaporizer is tipped over? (2)
Drain the vaporizer to remove all the liquid anesthetic.
Turn the dial to the highest setting and run a high FGF for 20–30 minutes.
What is the “T” setting on the vaporizer?
Setting the vaporizer to transport mode (T) eliminates the worry of tipping the vaporizer during transport or removal.
What is the most common cause of a vaporizer leak?
Loose filler cap
Does a variable bypass vaporizer need to be calibrated for elevation?
No
How many atmospheres is the Tec 6 desflurane vaporizer pressurized to?
2 atmospheres
What temperature is the Tec 6 desflurane vaporizer heated to?
39 degrees C
What vaporizer type varies inversely with elevation?
Tec 6
This matches (variable bypass vaporizer/tec 6)?
Compensates for elevation
Has temperature compensation valve
Variable bypass
Flow over design
Variable Bypass Vaporizer
This matches (variable bypass vaporizer/tec 6)?
Pressurized to 2 ATM
Requires electrical power
Dual circuit design
Does not compensate for elevation
Heated to 39 C
Datex-Ohmeda Tec 6
Which device will be the FIRST to detect an oxygen pipeline crossover?
Oxygen analyzer
Why will a pyrexic 70-kg patient become hypoxic with an oxygen flow rate at 250 mL/min in a closed-circuit system?
The VO2 for the average adult is 250 mL/min. Conditions such as fever, sepsis, and thyrotoxicosis will increase O2 consumption.
Normal oxygen consumption, VO2 for an adult
250 mL/min of O2
The oxygen analyzer resides in what limb of the breathing circuit?
Inspiratory limb
What are the MOST critical actions to perform during an oxygen pipeline crossover? (2)
Disconnect the pipeline supply.
Turn on the oxygen tank.
What 2 immediate actions must you take if the oxygen pipeline supply fails?
Turn ON the oxygen cylinder
Disconnect the pipeline oxygen supply.
What should be at the top of your differential when the O2 analyzer alarms?
O2 pipeline crossover until other causes can be ruled out.
Is the risk of barotrauma minimized by ventilators with fresh gas decoupling
Yes
Can excessive use of the O2 flush lead to awareness?
Yes due to dilution of anesthetic gasses
What 2 functions does the drive gas on an a pneumatic ventilator serve?
It compresses the bellows
It opens and closes the ventilator spill valve
What is the position of the ventilator spill valve during inspiration?
It’s closed. This ensures that the tidal volume goes to the patient and not to the scavenger.
What is the minimum expiratory pressure needed to open the ventilator spill valve?
3 cm H2O
Pressing the O2 flush exposes to breathing circuit what pressure?
50 psi (pipeline pressure)
Pressing the O2 flush exposes to breathing circuit what flow rate?
35–75 L/min
List 2 complications caused by overuse of the oxygen flush valve.
Barotrauma
Awareness
A leak/hole in the bellows may cause what 2 things
Increased oxygen analyzer reading and barotrauma
How does a leak in the bellows lead to barotrauma?
The ventilator drive gas compresses the pneumatic bellows. A leak in the bellows creates a direct line of communication between the ventilator drive gas and the breathing circuit.
How does a leak in the bellows increase O2 analyzer readings?
If there is a bellows leak and oxygen is used as the ventilator drive gas, the FiO2 in the breathing circuit may increase.
What is the problem with descending bellows during circuit disconnects?
A descending bellows may continue to rise and fall
How does an ascending bellows move during inspiration?
It falls.
Will a descending bellows fill during a circuit disconnect?
Yes—it can fill with entrained room air.
How will a bellows leak affect the inspired concentration of anesthetic agent?
It will dilute the anesthetic concentration (it goes down).
2 distinct advantages of a piston ventilator
preserves oxygen tank in the event of oxygen pipeline failure.
allows for more precise delivery of tidal volumes.
Are these things (true/false) of a piston ventilator?
Contains a positive pressure relief valve
Contains a negative pressure relief valve
Decouples FGF from Vt
Reservoir bag inflates during inspiration
True
Are these things (true/false) of a piston ventilator?
Requires a drive gas
Supplies 3 cm H2O of intrinsic PEEP
Reservoir bag inflates during expiration
False
Gas flow (accelerates/decelerates) during inspiration with pressure control ventilation
Decelerates
What ventilator mode decreases the risk of ventilator-associated lung injury
Pressure control
What parameters are fixed and what is variable in pressure control
Fixed: peak pressure
Variable: tidal volume
This is (volume control/pressure control)?
Vt is fixed
Inspiratory flow rate is fixed
PIP is variable
Volume Controlled Ventilation
This is (volume control/pressure control)?
Inspiratory flow rate is variable
PIP is fixed
Vt is variable
Pressure Controlled Ventilation
Which 2 modes of mechanical ventilation are BEST suited for a laryngeal mask airway?
Synchronized intermittent mandatory ventilation.
Pressure support ventilation.
Is this (true/false) of mechanical ventilation?
A risk of assist control is respiratory alkalosis
IRV requires a paralyzed and sedated patient
CMV is best suited for apneic patients
PSV-Pro is useful for a patient with an LMA
True
Is this (true/false) of mechanical ventilation?
Pressure support provides backup for apnea
BiPAP requires you to set the Vt
SIMV increases the risk of patient ventilator asynchrony
False
At what pH does the ethyl violet change to purple?
10.3
What are 2 major problems that can occur with carbon dioxide absorbent?
The absorbent is exhausted.
The absorbent is desiccated.
Why is silica added to soda lime?
It provides hardness and minimizes dust production.
What is the ideal mesh size for CO2 absorbent?
4–8 mesh
Does indicator dye alert you to CO2 absorbent desiccation?
No. It only tells you if the absorbent is exhausted.
When compared to soda lime, what factor is increased with the use of calcium hydroxide lime?
Frequency of replacement
3 benefits of calcium hydroxide lime (Amsorb Plus):
No carbon monoxide production.
Very little or no compound A production.
Lower risk of fire when compared to soda lime.
3 Drawbacks of calcium hydroxide lime:
Lower CO2 absorption capacity.
Requires more frequent replacement.
Higher cost.
Which component scavenger system determines if it’s an open or closed system?
The scavenging interface
What type of scavenging system communicates to the atmosphere with pressure valves?
Closed system
What 2 valves must be present on a closed interface - active scavenger?
Negative pressure relief valve
Positive pressure relief valve
What scavenger valve is malfunctioned when a patient requires FGF to fill the breathing bag?
Negative pressure relief valve
What is the MOST common cause of low circuit pressure?
Circuit disconnect
What part of the circuit is the most common cause of low circuit pressure?
Y-piece
Second most common cause of low circuit pressure
leak around the carbon dioxide absorbent.
What is the most common source of preventable equipment related complications?
Circuit disconnect
Recite 4 way to detect a circuit disconnect.
Pressure
Volume
EtCO2
Your vigilance
What should you do if the breathing circuit doesn’t hold pressure in the middle of a procedure?
Ventilate the patient with a bag-valve-mask and oxygen tank. Provide TIVA if necessary.
High peak pressure alarm sounds. After changing the bag selector switch from ventilator mode to bag mode, PIP returns to baseline. What causes the rise in pressure?
The ventilator spill valve malfunctioned.
What are 4 CV consequences caused by excessive pressure in the breathing circuit?
Decreased venous return
Decreased cardiac output
Hypotension
Cardiovascular collapse
Volatile anesthetics OSHA recommended exposure in ppm
less than 2 ppm.
Nitrous oxide OSHA recommended exposure in ppm
less than 25 ppm
VA with N2O, OSHA recommended exposure in ppm
less than 0.5 ppm
Which 2 components of the anesthesia machine could be affected if the low-pressure leak test fails?
Flowmeter.
Vaporizer.
The low-pressure leak test (negative pressure test) assesses
the low-pressure circuit’s integrity from the flowmeter valves to the common gas outlet
Which 2 situations would produce negative pressure inside the breathing circuit?
An orogastric tube placed in the trachea
Malfunction of a closed-system scavenger
A negative deflection is observed on the airway pressure waveform when the mechanical ventilator is activated. Which 2 mode of ventilation is the patient MOST likely receiving?
Pressure-support ventilation protect.
Biphasic positive airway pressure.
A negative deflection just before the breath indicates
a patient triggered breath
Inverse ratio ventilation and controlled mandatory ventilation require
an apneic patient
What is the MOST likely cause of a lower than expected concentration of sevoflurane inside the breathing circuit?
Bellows leak
Which agency regulates health care worker exposure to anesthetic gases in the operating room?
Occupational Safety and Health Administration
According to the US Department of Transportation, the gas cylinder label must include (2)
date of last inspection.
serial number.
The transfer tubing joins which components of the scavenger? (2)
APL valve.
Scavenger interface.
The gas disposal assembly tubing connects
scavenging interface to the gas disposal assembly.
The pressure in which type of cylinder will remain constant regardless of how much liquid is present inside the tank?
Carbon dioxide
The oxygen analyzer measures
O2 concentration inside the breathing circuit, making it the only safety device on the anesthesia machine that will alert you to an oxygen-pipeline crossover.
The failsafe device and hypoxia prevention safety devices help to prevent
a hypoxic mixture
What is the MINIMUM recommended pressure when performing a high-pressure leak test on the anesthesia machine? (Enter your answer in cm H2O)
30 cm H2O
What is the MAXIMUM flow rate delivered by the oxygen flush valve?
75 L/min
Soda lime that has changed color from purple to white occurs during
periods of nonuse
Does the soda lime color change from white to purple indicate desiccation?
No
What is the indicator dye used in soda lime?
Ethylene violet
Identify the final step in the soda lime reaction.
Na2CO3 + Ca(OH)2 —> CaCO3 + 2NaOH
What is the water content of soda lime?
15%
Which components creates the GREATEST resistance to airflow?
Endotracheal tube
The combination of sevoflurane and Baralyme increases the risk of:
breathing circuit fire.
flow tubes are tapered at
the base
flow tubes are wide at
the top
According to the World Health Organization, what color should an oxygen tank be painted?
White
Which 2 actions in the formulation of calcium hydroxide lime reduce compound A production?
Removal of NaOH.
Addition of Ca(OH)2.
DISS stands for
diameter index safety system
PISS stands for
pin index safety system
The SPDD model is used to understand
the pathway of gas through the anesthesia machine.
When replacing an oxygen tank on the anesthesia machine, using more than one washer between the cylinder and the yoke can lead to a/an:
inadvertent attachment of a nitrous oxide cylinder.
Which vaporizers are approved for the use of desflurane? (2)
GE-Datex-Ohmeda Tec 6. Drager D Vapor
best method to detect a vaporizer leak.
The low pressure circuit leak test
When the ambient temperature is increased, the bi-metallic strip in a variable bypass vaporizer directs (more/less) fresh gas to (bypass/vaporizing) chamber (2)
More fresh gas to the bypass chamber.
Less fresh gas to the vaporizing chamber.
