Anesthesia Delivery Systems (Mod 4) Flashcards

1
Q

Function of Anesthesia machine

A
  1. Delivery of medical gas, and volatile anesthetic (known conc)
  2. Removal of CO2 (via CO2 absorber and scavenging system)
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2
Q

How does the CO2 Absorber in an Anesthesia work?

A

The soda lime canister contains materials that absorb the CO2, they change color to blue when the soda lime is depleted, indicating another CO2 absorber needs to be swapped

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3
Q

What is a scavenging system

A

Collects and removes vented gases from operating room into the atmosphere

  • Active or passive
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4
Q

Electric and Pneumatic power source

A
  1. Electric powers the ventilator and associated monitors
  2. Pneumoatic power sources control gas flow and control medical gasses
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5
Q

Purpose of pressure regulators

A

Reduce pipeline and cylinders pressures

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6
Q

How does an Oxygen fail-safe device work?

A

Prevents delivery of hypoxic gas mixtures in the event of low or failed O2 supply

  • Requires Oxygen analyzer and supply failure alarm
  • Proportionately decreases (or shuts off) flow of all gases
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7
Q

How do O2 flush controls work

A

Emergency O2 flush valve

  • Bypasses the flowmeters and vaporizers
  • O2+, 35-75 L/min through circuit to flush out anesthetic gases
  • Activated by demand, designed to prevent accidental activation
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8
Q

How much O2 is used to flush out anesthetic gases?

A

35-75 mLs

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9
Q

Flowmeter sequence and Oxygen placement?

  • add slide 6
A

Oxygen is always downstream from the gases

  • Oxygen delivery is preserved in the event of a leak upstream
  • oxygen analyzer still needed to confirm correct delivery
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10
Q

What is the safest configuration of flowmeter tube arrangement?

A

Placement of O2, Air, and N2O are important.

  • safest = O2 nearest to the manifold outlet (to the right)
  • a leak upstream from the oxygen result in loss of nitrous oxide rather than oxygen
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11
Q

Why is arrangement of oxygen to the left dangerous and not to the right (closest to the manifold)

A

O2 flow can pass through the leak, while all nitrous oxide is directed to the common gas outlet

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12
Q

Function of the common gas line in an Anesthesia Machine?

A

Fresh gas outlet (Fresh gas flow)

  • mixture of medical gases and volatile anesthetics
  • Common gas outlet directs anesthetic mixtures to be delivered to patient
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13
Q

Breathing limb Function in an Anesthesia Machine?

A

Slide 7

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14
Q

Breathing circuit components

A

Insert slide 8

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15
Q

What is the purpose of vaporizers in Anesthesia machines?

A

Converts anesthetic from liquid to gas

  • Use is precise and accurate; measured amount of volatile gas is dispensed into the fresh gas mixture (done it 2 ways; flow over method and variable bypass)
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16
Q

What is the flow over method of vaporization for delivery of volatile gasses to fresh gas mixtures?

A

Gas flows over the liquid agent, becomes saturated

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17
Q

What does variable bypass mean in relation to vaporizer delivery of volatile gasses to fresh gas mixtures?

A

The gas flowing through the vaporizer is split, it either goes into 2 direction

  1. The amount passing into the vaporizing chamber is variable (based on operator adjusting settings)
  2. The rest bypasses the vaporizing chamber
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18
Q

Core characteristics of Vaporizers?

A
  • Agent specific
  • Variable bypass (concentration calibrated)
  • Flow over
  • Temperature compensated
  • Out of circuit
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19
Q

Colour for Sevoflurane

A

Yellow

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20
Q

Colour of Desflurane

A

Blue

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21
Q

Colour for Isoflurane

A

Purple

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22
Q

maybe add slide 13 and 14?

A
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23
Q

Vaporizer safety features

A
  • Agent specific, colour coded
  • Each bottle can only fill 1 vaporizer
  • Only one vaporizer can be on at a time
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24
Q

Ratio of O2 and N2O in a Controller?

A

Ratio must always be at least 1:3 (O2:N2O)

  • prevents <25% O2 delivery
  • Flowmeter for O2 and N2O are linked
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25
Q

4 circuit classifications for anesthesia machines?
- edit add image/more info on slide 15

A

Open, semi open, semi closed, or closed

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26
Q

3 common systems for Anesthesia circuits?

A
  1. Mapleson (6 system designs; Semiopen)
  2. Bain (modified vers of Mapleson D system, Semiopen)
  3. Circle (closed or semi closed) circuit…most common in Canada
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27
Q

Arrangements for Mapleson circuit

  • insert slide 18
A

6 arrangements, the components are:

  • FGF
  • Reservoir tubing
  • Facemask
  • Reservoir bag
  • Expiratory valve
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28
Q

Details on the Mapleson circuit system (a-f)?

  • circuit type (open/closed)
  • caveats?
A

Semi open circuit (no valves to direct gas flow)

  • no CO2 neutralization
  • Difficult to determine optimal FGF bc amount of rebreathing depends on FGF
  • Caveat: If the pt requires more FGF then the pt will be rebreathing…but no CO2 absorption system….meaning they rebreathe CO2
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29
Q

Best way to determine optimal FGF on a Mapleson system?

A

Monitor EtCO2

30
Q

Configuration of the Mapleson F (Jackson-Rees) circuit?

A

Pressure limiting overflow valve on reservoir bag

  • pediatric anesthesia (or tranpsort), Minimum dead space and resistance
  • Semiopen system?
  • No APL valve
31
Q

Disadvantages of Mapleson F circuit?

A
  • Requires high FGF to prevent rebreating…usually requiring 2-3x the patients MV
  • Potential for high airway pressure, barotrauma (if valve is occluded)
  • No humification system
  • Pollution of atmosphere with anesthetic gas ( can be hooked to scavenging system)
  • Semi open system (rebreathing issue?)
32
Q

Bain circuit system characteristics

A

Mod of Mapleson D; but the coaxial version…no CO2 neutralization or valves to direct flow tho. But some pros are:

  • FGF is warmed by exhaled gases
  • Moisture (from partial rebreathing)
  • Easy scavenging of waste gases from overflow valve
  • Semi open
33
Q

Disadvantages of Bain system?

A
  • Disconnect or kinking of inner FGF tubing
  • Requires high FGF
  • Circuit still has no valves to direct flow (semi open system)
34
Q

What kind of circuit type is a circle circuit?

A

Can be Semiopen, Semiclosed, or closed, it Depends on amount of FGF.

The following would apply to: Semi-closed and closed systems

  • Rebreathing of exhaled gasses = conservation of moisture/heat
  • Rebreathing = decreased pollution of exhaled anesthetic gas (bc its rebreathed) literally talking about the environment
35
Q

Decreased disadvantages of Circle Circuits

A

Increased airway resistance in system

  • Bulky, not portable
  • Higher risk of problems/malfunction
36
Q

Components of Circle Circuits

A
  • Insp/Exp unidirectional valves
  • Insp/Exp correugated tubing
  • APL Valve, reservoir bag
  • CO2 Absorbent
  • Bag/vent selector switch , ventilator
37
Q

Function closed circle circuits?

  • Advantages and disadvantages
A

Total rebreathing of exhaled gases

  • (A) Max warming and humidification of inhaled gases
  • (A) less pollution of atm exhaled gases and its economical
  • (D) can’t make rapid changes to delivered concentration of anesthetics or O2
  • (D) Unpredictable concentrations of anesthetics and O2
38
Q

Bispectral Index (BIS monitor)

A

Level of consciousness (EEG activity)

  • Usually aim for 40-60 for healthy patient and routine anesthesia
  • Non invasive monitoring
39
Q

Review EtCO2 monitoring

  • Slide 28 forward for EtCO2 waveforms
A
40
Q

When is MAC measured?

A

As the end tidal concentration of anesthetic gas

41
Q

Purpose of a APL valve?

A

Pressurizes the circuit; known as the pop off valve/pressure relief valve

  • Regulates the pressure within the breathing circuit and protects the pt from escessive pressures during mech ventilation
42
Q

Should the APL valve be left opened or closed if the patient is spontaneously breathing?

A

Open..the patient would be able to exhale if the valve is closed.

  • The patient provides back pressure when spontaneously breathing, the valve won’t let anything through
43
Q

2 ways in which measured volatile gas is dispensed into fresh gas mixtures (via vaporizers)

A
  1. Flow over method of vaporization
  2. Variable bypass
44
Q

Why are Vaporizers out of circuit

A

Its so that exhaled gasses don’t recirculate

45
Q

Anesthesia machine safety features (not the same as the vaporizers) 8

A
  • Cylinders are specific, color coded with PISS connectors and safety pressure relief
  • O2 flowmeter (control is diff form other gasses and is downstream in case of leaks)
  • O2 fail safe valve (prevents hypoxic gas delivery, occurs when O2 is less than 30psi)
  • Alarms
  • Min O2/N2O controller
  • Vaporizer safety features
  • Back pressure check valve (prevents back pressure from PPV going into the machine)
  • Machine checks and alarms (person does it)
46
Q

How does the minimum O2/N2O controller work (saftey feature)

A

Flowmeter controls O2 and N2O are linked, it ensures that a 1:3 concentration is met

  • Prevents < 25% O2 delivery
47
Q

Anesthesia machine circuits are defined as open, semiopen, semiclosed, or closed, What does the classification of the systems depend on?

A

Whether there are the following elements present (some may not be in the circuit):

  1. Gas reservoir bag in circuit
  2. Rebreathing of exhaled gases
  3. Chemical neutralization of CO2
  4. Unidirectional valves
48
Q

Since the Mapleson configuration is difficult to monitor optimtal FGF, what is the best way to manage gasses so that rebreathing is not dangerous?

A

Monitor EtCO2 and the amount of anesthetic gas at end exhalation…but its still not perfect

49
Q

How does the Mapleson F (Jackson rees) differ from other Mapleson setups?

A

Modified Mapleson D configuration that has a pressure limiting overflow valve on reservoir bag (meaning minimum dead space and resistance)

50
Q

What population would likely use the Mapleson F setup?

A

Pediatric anesthesia (or in transport)

  • due to min dead space and resistance so less risk of vili
51
Q

How does the Bain circuit warm and moistures the FGF?

A

The FGF tubing runs inside the corrugated expiratory tube

52
Q

Why is the Bain Circuit better than the Mapleson circuit?

A

Less mixing of gases; where its separate tubing

  • In controlled ventilation: you can control the inspiration, minimizing rebreathing of gasses
  • FGF is warmed and moisturized
  • Less rebreathing of CO2 at lower FGF flow
53
Q

How do closed circuits work in a circle circuit?

A

The inflow of fresh gas flow exactly matches the gas being used by the patient

  • You need to know the exact inspiratory need of the patient, and that’s what you’ll get
54
Q

Where does the scavenging of system vent collected gas from the OR?

A

Out of the roof of the building, with the rest of the medical gasses that are collected and vented

55
Q

When is the Closed Circle Circuit considered for use?

A

Once CO2 is removed, than it implies anything you give is given.

  • removing the CO2 from the tissue is difficult though
56
Q

Which systems include a CO2 Neutrilzer?

A

Semi closed and closed circles systems

57
Q

Do semi open systems allow for rebreathing of exhaled gasses

A

Generally no, if there is its because of insufficient FGF (so its bad…)

  • only semi closed or closed circle systems allow purposely allow rebreathing
58
Q

What level of FGF flow rate required for open breathing systems

A

Unknown amount due to variable nature

59
Q

What level of FGF flow rate required for Mapleson breathing systems (semi open)

A

High FGF rate

60
Q

What level of FGF flow rate required for semi closed breathing systems?

A

Moderate low FGF rate

61
Q

What level of FGF flow rate required for closed breathing systems

A

Low FGF rate

62
Q

Open drop system?

A

Open system

63
Q

Does the Mapleson (semi open) system direct flow?

A

Only has 1 unidirectional valve (APL valve) to direct flow.

  • no valves to direct gas to and from patient
  • Needs high FGF
64
Q

Why is rebreathing okay in semi closed systems?

A

The delivery of FGF is above the patient requirement, so its not dangerous…monitoring of CO2 analyzer

65
Q

What does the following EtCo2 waveform indicate

A

Rebreathing

66
Q

What does the following EtCo2 waveform indicate

A

Airway Obstruction

67
Q

What does the following EtCo2 waveform indicate

A

Muscle Relaxants

68
Q

What does the following EtCo2 waveform indicate

A

Esophageal ETT

69
Q

What does the following EtCo2 waveform indicate

A

Poor seal or leaky ETT or uncuffed Trach

70
Q

What does the following EtCo2 waveform indicate

A

Increasing EtCo2 levels

  • could point to a potential malignant hyperthermia if temperature also rises
71
Q

What does the following EtCo2 waveform indicate

A

Decreasing EtCO2 levels

  • hyperventilation
  • decrease in metabolic rate
  • decrease in body temp
72
Q
A