2 - Anesthesia Machine Flashcards

1
Q

Most important item in the preuse checklist

A

Functioning self-inflating resuscitation bag (SIRB) and full auxiliary tank of oxygen

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2
Q

What is the “vulnerable” area of the workstation?

Why?

A

Low pressure circuit (LPC)

Most subject to breakage and leaks, and also downstream from most detectors

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3
Q

What is the only sensor monitoring LPC integrity in an ongoing fashion?

A

Oxygen Analyzer

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4
Q

Which test checks the integrity of the anesthesia machine from the flow control valves to the common gas outlet?

A

LPC leak test

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5
Q

Why are flowmeter leaks a significant hazard?

A

They are downstream from any safety sensor except the oxygen analyzer

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6
Q

What is the calculation for pressure?

A

P = Force/Area

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7
Q

What is PSI?

A

Pounds per square inch

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8
Q

What is a boiling point?

A

The point at which liquid becomes gas

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9
Q

What four actions should you immediately take if pipeline pressure is lost or crossover is suspected?

A
  1. Turn on the backup oxygen cylinder
  2. Disconnect completely the wall/pipeline supply
  3. Turn off the ventilator and use the circle system
  4. Convert to total IV anesthesia
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10
Q

Leaks in the LPC can lead to:

A

delivery of hypoxic injury

awareness during anesthesia

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11
Q

Which gas requires specialized vaporizers?

Why?

A

Desflurane

Has a low boiling point and high vapor pressure

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12
Q

The APL valve prevents what kind of injury?

A

barotrauma

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13
Q

The LPC leak test checks the integrity of the machine from _____ to _____

A

flow control valves

common gas outlet

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14
Q

What is present at the pipeline inlet?

A

filter

check valve

pressure gauge

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15
Q

What does a check valve prevent?

A

Leakage when the supply is disconnected

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16
Q

What is a common factor related to patient injury during cross-connection?

A

Failure to use an oxygen analyzer

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17
Q

What would you see in the event of a crossover?

A

declining inspired O2 concentration

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18
Q

When should cylinders be open?

A

Only when they are checked or when pipeline supply is unavailable

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19
Q

What system uses PISS?

DISS?

A

Cylinder

Pipeline

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20
Q

PISS for O2?

N2O?

Air?

A

2-5

3-5

1-5

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21
Q

Psi in an O2 tank?

Nitrous?

Air?

A

1900

745

1900

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22
Q

Capacity of an O2 tank?

Nitrous?

Air?

A

660

1590

625

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23
Q

What is the most fragile part of the cylinder?

A

Cylinder valve

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24
Q

Why is transfilling a potential fire hazard?

A

filling a cylinder produces heat! Gas laws!

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25
Q

The cylinder pressure gauge is what kind of gauge?

A

Bourdon

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26
Q

Cylinder pressure is ______ than pipeline pressure

A

slightly lower (45 vs 50)

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27
Q

If a cylinder is open and the gas pipeline shuts off, will you get an alarm?

A

Not until the cylinder is empty

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28
Q

Using the ventilator, how long will a full tank of O2 usually last?

A

1 hour

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29
Q

When does the low oxygen supply failure alarm go off?

A

At the end of the emergency supply, instead of its beginning

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30
Q

Why is hospital compressed air drier than atmospheric air?

A

Dehumidified to prevent damage to equipment

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31
Q

New anesthesia machines are equipped with at least ______ backup power

A

30 min

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32
Q

Which items do not rely on electrical supply?

A

spontaneous/assisted ventilation

manual blood pressure cuff

mechanical flowmeters

variable bypass vaporizers

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33
Q

What is fail safe valve?

A

Held open by O2 flow

Closes when O2 flow stops

prevents flow of hypoxic mixture to patient

Not present on O2 or air

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34
Q

What are the five tasks of oxygen?

A
  1. proceeds to fresh gas flowmeter
  2. Powers the oxygen flush
  3. Activates fail safe mechanisms
  4. Activates oxygen low pressure alarms
  5. Compresses the bellows of mech vent
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35
Q

All gases except oxygen have ______ pathway.

A

One: to patient via flowmeter

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36
Q

Which valve controls gas flow through the flowmeter?

A

Needle valve

37
Q

What are the components of a flowmeter?

A

knob

needle valve

valve stops

flowtube

indicator float

38
Q

Why is the flowtube referred to as a variable orifice flowmeter?

A

the annular opening around the float is larger at higher flows

39
Q

Never adjust a flowmeter without _________

A

looking at it

40
Q

Failure to turn the flowmeters off at the end of the case can result in damage to what?

A

CO2 absorber
Generates CO in canisters

can cause canister fires

41
Q

When should the auxiliary oxygen source not be used?

A

During pipeline failure/crossover

42
Q

Common gas outlet flowmeters

A

Shows pipeline flow as a backup on machines with electric flow displays

43
Q

How much gas is a flush valve required to provide?

A

35-75 L/min

44
Q

When should you NEVER active O2 flush?

A

During the inspiratory phase

45
Q

How can you inflate the bellows without flushing?

A

Increase fresh air flow to 8-10 L/min

46
Q

Compare old and new low pressure alarms?

A

Old ones sounded like a whistle

New ones are electronic

47
Q

In proportioning systems, the ration of nitrous to oxygen is never greater than _______

A

3:1

48
Q

What are four situations where the hypoxic guard system allows hypoxic mixing?

A
  1. Wrong gas in pipeline/tank
  2. Defective pneumatics/mechanics
  3. Leaks downstream of flow control valves
  4. Inert gas administration (i.e. helium)
49
Q

What is the only system that ensure oxygen is present in the breathing circuit?

A

Inspired oxygen analysis

50
Q

Monitoring inspired oxygen is required in what circumstances?

A

Every general anesthetic

51
Q

When should the oxygen monitor be checked?

A

Before every case, even if general anesthesia is not anticipated

52
Q

What are the two types of inspired oxygen sensors?

A

Paramagnetic and galvanic

53
Q

What is a vapor?

A

Liquid at room tempreature and 1 atm

54
Q

Measured flow (vernitrol) vaporizers require manual ___________

A

temperature compensation

55
Q

What’s the difference between variable bypass and Tec 6 inejctor vaporizers?

A

Air flow: in variable bypass flow passes over liquid agent, in Tec 6 fresh gas never comes into contact with the liquid agent

Tec 6 is heated

In VB % is acheived by modulating flow

in Tec 6 % is acheived by modulating heat

56
Q

How is an operator prevented from giving more than one vaporized gas at a time?

A

Interlock system

57
Q

What is optimal wash-in?

A

Using high fresh gas flow (nonrebreathing @ 5-8L/min) during induction, and using low fresh gas flow during maintenance

58
Q

The degree of rebreathing is increased as ________ is decreased

A

fresh gas flow

59
Q

The higher the fresh gas flow, the more quickly the composition of gas in the breathing circuit will resemble __________

A

the dialed in concentrations at the common gas outlet

60
Q

Rebreathing of exhaled nitrogen _______ induction.

A

Slows

61
Q

What effect does dead space have on degree of CO2 rebreathing?

A

Increased dead space = increased rebreathing

62
Q

Which has more dead space: a facemask or an ETT?

A

A facemask

63
Q

Where does dead space end on a breathing circuit?

A

The y piece

64
Q

Why is emergence not the same thing as passively waking up?

A

Decreased concentrations of inhaled gases cause wash out while ventilation is continued

65
Q

Circle system at high fresh gas flow (greater than minute ventilation) is considered open or closed?

A

semi-open

No rebreathing

66
Q

Circle system at low fresh gas flow (less than mV) is open or closed?

A

Semi closed

Partial rebreathing

67
Q

Circle system at extremely low fresh gas flow with APL valve closed is open or closed?

A

Closed

Complete rebreathing

68
Q

What are common features of nonrebreathing systems?

A

Lack unidirectional valves

lack soda lime carb dioxide scrubbers

fresh gas flow determines the amount of rebreathing

Resistance and work of breathing are low

69
Q

Circle system allows rebreathing of ________ but not ________

A

All other gases

CO2

70
Q

What are the two common reasons for increased inspired CO2 in a circle system?

A

exhausted CO2 scrubber

faulty unidirectional valve

71
Q

If more than 1-3 mmHg of inspired CO2 is present in a circle system, what should you do?

What if that doesn’t work?

A

Increase the fresh gas flow to 5-8 L/min

This converts the system into a semi-open system, which minimizes rebreathing

If it works, the problem is the scrubber. If it doesn’t the problem is a valve.

72
Q

How do you check unidirectional valves before use?

A

Spare breathing bag on the y piece, observe the valves lifting and falling. Test with both ventilator and circle.

73
Q

What happens when sevoflurane encounters soda lime?

A

Produces Compound A which is lethal in rats and can cause renal damage

74
Q

You should not use sevo with gas flows less than _______ and more than ______ hours

A

1-2 L/min

2 MAC hours

75
Q

Degradation of Desflurane in soda lime produces what?

A

carbon monoxide

76
Q

Do CO2 scrubbers significantly increase circuit resistance

A

No. Creates less resistance than the ETT.

77
Q

What are early clinical signs of CO2 scrubber exhaustion?

A

Increased EtCO2 and inspired CO2

Respiratory acidosis

hyperventilation

SNS activation

Bleeding at surgical site

+ color change

78
Q

What are late signs of carbon dioxide scrubber exhaustion?

A

Increased (then decreased) HR and BP

Dysrhythmia

79
Q

A higher fresh gas flow will ____ the lifetime of a scrubber

A

increase

80
Q

What is the current recommendation for Vt?

RR?

I:E?

A

5-7ml/kg IBW

6-12

1:2

81
Q

How should you adjust the ventilator if end-expiratory flow is incomplete before the next waveform begins?

A

Decrease RR

Prolong the I:E

82
Q

Which patients may benefit from PCV?

A

those for whom high inspiratory pressure is dangerous:

Neonates

laryngeal mask airways

emphysema

83
Q

What should you think first when there is a change in the patient’s condition is noticed?

A

Think back to the last alteration made to the equipment, or last drug given, and determine if that could be responsible

84
Q

What is the threshold for smelling anesthetic gases?

A

5-300 ppm

ALWAYS ABNORMAL

85
Q

What is fresh gas decoupling (FGD)?

A

Circle breathing system where fresh gas is piped into the resevoir bag during the inspiratory phase. When the expiratory phase begins, the gas in the resevoir bag flows into the bellows and is given with the next breath, and so the Vt includes the amount of fresh gas.

86
Q

What is the greatest disadvantage of FGD?

A

increased possibility of air entrainment that dilutes the fresh gas and could go undetected.

Also, can’t be any problems with the resevoir bag

87
Q

Which machine uses FGD?

A

Drager

88
Q

Which machine dispenses with the need for a bellows or piston for PPV?

How?

A

The Maquet FLOW-i

Uses a volume deflector

89
Q

Why is the volume reflector more economical than a bellows or piston?

A

fresh gas flows into the reflector only during the inspiratory phase rather than continuously throughout the respiratory cycle