Anesthesia Machine

Question 1

What is the role of AAN Standard VIII?

Answer 1

To adhere to proper safety regulations for anesthesia equipment and the anesthesia machine.
This is to check for machine malfunction and ensure the equipment is running effectively.

This to ensure document compliance. Machines will record the last time they are checked.

Question 2

What is needed for anesthesia machine monitoring?

Answer 2

There are specific safety features, including a device that detects disconnection that emits an audible alarm.

monitor inspired O2 concentration continuously with a low concentration alarm.
-This is to prevent the deliverance of a hypoxic mixture to the patient.

Question 3

What are the machine subsystems for the anesthesia machine?

Answer 3

Supply
Processing
Delivery
Disposal/Scavenging

Question 4

What are the four subsystems of the anesthesia machine?

Answer 4

High pressure system: Where there is a high-pressure system (pipeline or the e-cylinder)
-pipeline is the most common form that we will see in the hospital system.

Low pressure system: blending of gases and volatile agent based on control settings

Breathing system: fresh gas mixture passes from machine to patient

Scavenging system: collects and. disposes of excess gases.

Question 5

What are the standards for the pipeline gas inlet?

Answer 5

Filters and check valves

This helps to ensure that the gas is only going in one direction.

Question 6

Describe the pressure gauges

Answer 6

O2 is green, air is yellow, nitrous is blue.
-These are the carrier gases.
-Pipeline is on the top, cylinder is on the bottom foe the gauges.

Question 7

What is the expected pressure for the pipeline?

Answer 7

50 to 55 psig (psi)

-this is important to remember.

Question 8

What is the safety system for the pipeline?

Answer 8

DISS- Diameter Indexed Safety System
-The diameters are different on the connections to prevent the connection of wrong hoses to inlets. ex- cannot connect O2 to nitrous, only to O2. Different connections prevent this. Gas specific.
-Some machines have different connections, a screw in system, but the diameters should still be different and gas specific.

Question 9

What is a hanger yoke?

Answer 9

orients cylinder, provided seal, directs flow.

-Forces the cylinder to go on correctly.
-There is a washer that goes on the cylinder on the hanger yoke. This is to provide the seal and is needed to prevents leaks.

Question 10

What is a check valve?

Answer 10

It prevents retrograde flow and transfilling to second cylinder of the same gas.
-This prevents transfilling (equalizing of cylinders as one empties and the other is full)

Question 11

What is a pressure regulator?

Answer 11

It reduces the pressure to 45 psig -this is pressure of the cylinder.
-this helps the prevention of pneumos.

-machine will pull from wall first if it is plugged up due to the higher pressure coming from the pipeline than the cylinder. If the pressure decreased, then it would pull from the cylinder instead.

-You should check that the cylinder is at least half/full and then turn it back off. This is the backup source of O2.

Question 12

What are the pressure gauges?

Answer 12

Bourdon-type gauges - start at 0
-Make sure you flush out the air between the cylinder and the gauge between checks to have the correct pressure. To do this, you have to disconnect from the wall because this forces the machine to use what is between the cylinder and the gauge.

Question 13

What is the Pin Index Safety System?

Answer 13

This is also a gas specific system to help only certain cylinders go onto certain yokes.

Remember the positions.
O2 2-5
Nitrous oxide 3-5
Air 1-5

Question 14

What is Bourdon-type gauge?

Answer 14

This is the flexible

Question 15

What is the O2 power outlet?

Answer 15

This is connected to the mechanical ventilator and O2 flush valve.

Question 16

Discuss the O2 flush valve

Answer 16

This bypasses flowmeters, vaporizers- delivers directly to breathing system (50 psig)
-delivers 35 to 75 L

Question 17

When do you have an alarm for low O2 supply?

Answer 17

Will sound if O2 drops below 30 psig for longer than 5 seconds.
-This is important because it is how you would know if your pipeline has been disconnected.

Question 18

What is the O2 pressure failure safety mechanism?

Answer 18

This causes the cessation of flow of non-oxygen gases if the O2 pressure drops to or below 25 psig.
-This is to prevent a hypoxic mixture.

Question 19

Discuss flowmeters components

Answer 19

Flow control valves- controls gas flow through the flowmeter.
knob-
needle valves- controls the gas flow
flow tubes-calibrated to the density/viscosity to whatever specific gas they are designed for. They are coated with a conductive surface to help prevent static. They are tapered
-referred to as thorpe tubes.
Indicator float

Question 20

What is the touch-index safety feature for control knobs?

Answer 20

They are fluted, have a size difference, protrudes further, and most right.
-This is all true for the O2 concentration.

Question 21

What does the proportioning system provide in safety?

Answer 21

It prevents the deliverance of a hypoxic mixture. It will not allow a ratio of N2O to O2 not more than 3:1. The knob for O2 will turn along with the nitrous if they nitrous is turned too high. (This is the link 25 system)

-One of the portions of a machine check is to try to make an incorrect ratio to ensure the machine corrects it or doesnt allow it.

Question 22

What is the minimal O2 flow?

Answer 22

150 mL/min of oxygen to help meet their basal metabolic needs even if the operator forgets to turn the flow on. Another safety feature.

Question 23

Why does the positioning of the flowmeters matter?

Answer 23

The O2 flowmeter is always nearest to the vaporizers (downstream on right)

This minimizes the risk of hypoxic mixture being delivered if a leak occurs in the flowmeters (there would be a higher risk of hypoxia if leak occurs within the ox flowmeter or downstream)

Question 24

What is the manifold?

Answer 24

This is where gases from different flowmeters mix together and have the opportunity to enter into a vaporizer which is attached here.

Question 25

What is a calibrated vaporizer?

Answer 25

This adds a vaporized anesthetic agent to the gas flow.

Question 26

What does an interlock exclusion system do?

Answer 26

This prevents using more than one vaporizer at a time.

Question 27

What is the common gas outlet?

Answer 27

This supplied the gas mixture to the breathing system. Where the supply comes out of the machine at the appropriate pressure and mixture. Ready to be delivered to patients.

“fresh gas outlet”

This is where you perform low-pressure circuit leak tests.

Safety feature is an antidisconnect device.

Question 28

What are the portions of the breathing system?

Answer 28

Fresh gas hose, inspiratory and expiratory unidirectional valves, breathing hoses of circuit, Y-piece, and adjustable pressure limiting valve. (APL or pop-off valve)

CO2 absorber housing, CO2 absorbent canister, breathing system pressure gauge, reservoir bag, bag/ventilator selector switch.
-absorbent granules will turn purple when saturated. This is also another potential site for a leak.

ventilator

Question 29

What are the components of the ventilator?

Answer 29

Ventilator drive gas tube
hose
bellows
pressure relief valve (spill valve)

Question 30

What are the safety features for the breathing system?

Answer 30

Antidisconnect fresh gas hose connector
Antidisconnect pressure sampling line connection -leak potential
Vent low airway pressure alarm
Vent pressure-limiting adjustment knob
Vent pressure relief valve

Question 31

What does the hospital use for scavenging system?

Answer 31

The active system- this is a vacuum (negative pressure) from hospital disposal system withdraws gas from the scavenging system.
-white or purple tube usually.

Question 32

Passive scavenging system

Answer 32

Slight positive pressure of excess gases in the machine moves it into the evacuation hose and into the disposal system
-this is seen more in medical mission trips.

Question 33

What are the types of scavenging systems?

Answer 33

Active and passive

-These systems are an environmental safety concern. This system is passive, so the tube needs to be plugged into the disposal system, not on the floor.

Question 34

Things to check for scavenging system

Answer 34

That the valves are working, it is hooked up to suction, and the pressure is not too great or too little.

The indicator on the scavenging system pressure needs to be between 2 white lines. This is the appropriate amount.
-If it is the bag scavenger system set up, then it needs to be checked during the machine ventilator check to ensure that the bag is not too full and is not staying minimally compressed.

Question 35

What are the components of the scavenging system?

Answer 35

Collecting hoses
Intake ports
reservoir
manifold
vacuum control
exhaust port and evacuation hose

Question 36

What are the safety features for the scavenger system?

Answer 36

different size hoses
closed interfaces
-positive pressure relief mechanism: if vacuum is not high enough, pressure will not back up in the breathing system
-negative pressure relief mechanism: if the vacuum is too strong, the gases to be delivered to the pt will not be affected.
open interfaces
-needs appropriate suction or exhalation pollutes the OR.

Question 37

When does the gas go to scavenging?

Answer 37

-manual vent: gas enters the scavenging system when the peak pressure exceeds the opening pressure of the APL valve
-mech vent: during late exhalation and the expiratory pause after the vent bellows have returned to full position.
-spont vent: during late exhalation.

Question 38

What are the five functions of oxygen in the anesthesia machine?

Answer 38

Go to the O2 flowmeter
Go to O2 flush
Activate O2 pressure failure safety mechanism (fail-safe)
Activate O2 low-pressure alarm
Powers the mechanical ventilator bellows

Question 39

What are the primary purposes of the machine?

Answer 39

Provide O2
Blend the anesthetic gas mixture
To allow ventilation of patient’s lungs, whether spontaneous, assisted, or controlled.