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2-General Principles Exam 3 > Gas Machine Part II > Flashcards

Gas Machine Part II Flashcards

1
Q

Review the systematic components of the gas machine.

A
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2
Q

What are the oxygen tasks?

A
  1. Proceeds to fresh gas flowmeter
  2. Powers oxygen flush
  3. Activates fail safe mechanisms
  4. Activates oxygen low pressure alarms
  5. Drives bellows
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3
Q

What is the source of the systems supply of the Gas machine?

A

Pipeline & Tanks

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4
Q

Flow meters: What is the properties of the knobs?

A

Knobs color and touch coded

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5
Q

Flowmeters: How are flows measured?

A

Flows measured by mechanical needle valves or electronic flow controls

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6
Q

Flowmeters: What is the gas flow range?

A
  • Gas flows range between 200mL and 15L
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7
Q

Flowmeters: What is the oxygen flow?

A
  • Minimum oxygen flow is provided by an adjustable stop on the oxygen flowmeter control knob
  • 200-300mL
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8
Q

Flowmeters: What is the spacing between knobs?

A

Spacing between knobs is a minimum of 25mm

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9
Q

Flowmeters: What is the oxygen calibrated to?

A

to +/- 5% concentration at room temperature and sea level

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10
Q

Flowmeters: What does it mean that flowmeters are variable orifice?

A
  • Narrower at the bottom
  • May be arranged in series
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11
Q

Flowmeters: What is the design principle?

A

Thorpe tube design principle

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12
Q

In U.S. oxygen flowtube placed to the ________ of other flowtubes

A

right

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13
Q

What is the most fragile part of the AGM?

A
  • Glass flowtubes most fragile part of AGM
  • Breakage, leaks, dirt or static electricity lead to inaccuracy
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14
Q

How do you avoid damage to the glass flowmeters?

A

Avoid risking damage to glass flowmeters by turning them off before connecting pipelines, opening cylinders or turning on AGM

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15
Q

What is true about newer AGM and flowmeters?

A

Some newer AGMs use anemometer to electronically capture flow to avoid the use of glass flowtubes

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16
Q

What is the principle that flowmeter’s are found?

A

Graham’s Law

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17
Q

What is the characteristics of variable orifice?

A
  • Tapered tube with larger diameter at the top than at the bottom
  • Rotating float or bobbin is lifted by the gas until equilibrium is met
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18
Q

What is true about the flow in flowmeter?

A

Variable Orifice

  • As gas flows around the indicator, it encounters frictional resistance between the float and the walls of the tube
  • Flow becomes less laminar and more turbulent
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19
Q

What are the different types of flowmeters?

A

Indicators or Floats

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20
Q

Where do you measure the flowmeters?

A
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21
Q

Electronic Flowmeters: _______ more accurate than glass flowtubes

A

5 to 10 times

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22
Q

What is the prinicple behind electronic flowmeters?

A
  • Utilize solenoid principle
  • Known mass of gas is registered and measured
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23
Q

What is true about machines with electronic flowmeters?

A

On machines with electronic controls for flow, backup oxygen controls using mechanical/pneumatic needle valves are present in case of electronic or electrical failure

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24
Q

AGMs with electronic flows have a ___________ to display total gas flow in case of electrical power failure

A

backup pneumatic/mechanical flowmeter

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25
Q

What are other AGM flowmeters?

A

Auxiliary oxygen flowmeter, Common gas outlet flowmeter and Scavenging flowmeter

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26
Q

What is the auxillary oxygen flowmeter?

A
  • Typically used for nasal cannula or face mask oxygenation
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27
Q

What is the prinicple about the auxillary oxygen flowmeter?

A

Separate from the breathing circuit

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28
Q

Where does the auxillary oxygen flowmeter receive its oxygen supply?

A

Relies on pipeline oxygen

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29
Q

What is true about the oxygen content in the auxillary oxgen flowmeter?

A

Oxygen content unable to be diluted (e.g. decreased to 30%)

30
Q

When are uCommon gas outlet flowmeter used?

A

Used on AGMs with electronic displays

31
Q

What is the purpose of the Common gas outlet flowmeter?

A

Serve as a backup and are only indication of oxygen flow if computer display fails, or in case of power failure after battery backup is exhausted

32
Q

When is the Scavenging flowmeter used?

A

Used with AGMs that have open scavenging interfaces

33
Q

What is the purpose of Scavenging flowmeter?

A

Indicates adequacy of suction to avoid exposure to waste gases

34
Q

Locate the auxiliary oxygen flowmeter.

35
Q

Review image of scavening flowmeter?

36
Q

How much oxygen does the oxygen flush deliver?

A

Delivers 35-75L/min oxygen and pressure

37
Q

What are the characteristics of oxygen flush?

A

Quickly fills the breathing circuit with oxygen

38
Q

What is the risk of oxygen flush?

A

High risk for barotrauma, especially if activated during inspiration

39
Q

When should the oxygen flush be administered?

A

Activate in short pulses during patient expiration

40
Q

What is the source of the oxygen flush?

A
  • Runs directly from the gas supply source to the common gas outlet
  • Bypasses vaporizers
41
Q

What do you need be aware of with the oxygen flush?

A
  • Adds 100% oxygen to breathing circuit
  • Beware of dilution
42
Q

What is the purpose of fail safe mechanisms?

A

Prevent administration of a hypoxic mixture of gases if pipeline oxygen pressure fails with N2O flowing

43
Q

What does the fail safe mechanism stop?

A

Stops the supply of gases (+/- air) other than oxygen when oxygen supply fails

44
Q

What is true about the concentration of oxygen at the common gas outlet?

A

does not decrease if pipeline pressures decrease

45
Q

What is related to the fail safe in non oxygen gases?

A

have gate-like valves held open by pressure in the oxygen line

46
Q

How is nitrous oxide shut off?

A

Flow of nitrous oxide shut off or proportionally decreased

47
Q

What do fail safe systems analyze?

A

Fail safe systems do NOT analyze oxygen content, only pressure

48
Q

What is a low pressure alarm indicate?

A

Alarm when pressure is lost in the oxygen circuitry

49
Q

What do older low pressure alarms?

A

Loud whistle that blew with pipeline pressure <28 psi or machine shut off

50
Q

What do newer low pressure alarms?

A

Visual and auditory alarms

51
Q

What does the ventilator driving gas cause?

A
  • Causes compression of the bellows
52
Q

What is true about the driving gas and some AGMS?

A

Some AGMs use 100% oxygen as the driving gas, others can use air or oxygen

53
Q

What is the exception to the ventilator driving gas?

A

In piston ventilators electric motors compress bellows and do not need oxygen pipeline supplies, e.g. can use compressed gases from cylinders to run the AGM because oxygen is not used to drive the bellows

54
Q

What is the Proportioning Systems known as?

A

Hypoxic Guard

55
Q

What does the Proportioning Systems (Hypoxic Guard) prevent?

A

prevent hypoxic mixture of oxygen and nitrous oxide

56
Q

What is the link between oxygen and nitrous oxide?

A

Oxygen and nitrous oxide flows linked to keep FiO2 between 0.23-0.25

57
Q

What is the properties of the Proportioning Systems (Hypoxic Guard)?

A

May be mechanical (chain-linked) or electrical in nature

58
Q

What is the proportioning ratio to nitrous oxide and oxygen?

A

Proportioning ratio: nitrous oxide to oxygen ratio no more than 3:1

59
Q

What is another name for the chain link?

A

the Link-25 proportioning system

60
Q

What are circumstances in which the Proportioning Systems (Hypoxic Guard) would fail?

A
  1. Wrong supply of gas in oxygen pipeline or cylinder
  2. Defective pneumatics or mechanics
  3. Leaks downstream of flow control valves
  4. Inert gas administration (e.g. helium)
61
Q

What is the most accurate umethod of detecting hypoxic gas mixture from AGM to the patient?

A

Oxygen Analyzer (Oxygen Monitor)

62
Q

What does the Oxygen Analyzer (Oxygen Monitor) sample?

A

Samples the oxygen line to determine that oxygen is present

63
Q

What are the Low pressure alarms, hypoxic guard systems and fail-safe systems are based on?

A

pressure, not inspired oxygen sampling and analysis

64
Q

What are the types of sensors?

A
  • Electrochemical or galvanic fuel-cell
  • Paramagnetic
65
Q

What AGMs have Electrochemical or galvanic fuel-cell?

A

Aestiva, Aespire

66
Q

What is the pargmagnetic sensor?

A

Widely used due to fast response, low cost and low maintenance

67
Q

What do the galvanic cells (Oxygen sensors) contain?

A

Contain two electrodes, a lead anode and a gold cathode, surrounded by an electrolyte bath

68
Q

What are the properties of the galvanic cells (Oxygen sensors)?

A

Oxygen molecules diffuse through a Teflon membrane and are reduced at the gold Cathode to hydroxyl ions which react with the lead cathode to form lead oxide and in the process release electrons

69
Q

What is the galvanic cells (Oxygen sensors) calibrated too?

A
  • Calibrate to room air
  • Should calibrate in 15-20sec
  • Longer than 60sec consider replacing
70
Q

How does the Paramagnetic work?

A
  • Oxygen molecules have two electrons in unpaired orbits (paramagnetic)
  • Susceptible to attraction by a magnetic field
71
Q

How is the Paramagnetic oxygen analyzer calibrated?

A
  • Need periodic (every 3-6mo) exposure to calibration gas
  • Last for years

2-General Principles Exam 3 (11 decks)

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