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JW: Principles of Anesthesia I > Exam 3- Compressed Gases and Vaporizers (7/10/23) > Flashcards

Exam 3- Compressed Gases and Vaporizers (7/10/23) Flashcards

1
Q

PSI stands for

A

Pounds per square inch

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2
Q

What were examples of gases that do not liquefy at ordinary ambient temperatures regardless of the pressure applied?

A
  • Oxygen
  • Nitrogen
  • Air
  • Helium
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3
Q

A liquified gas can become a liquid at ambient temperature and at pressures from ____- _____psi

A
  • 25 to 1500 psi
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4
Q

What were examples of liquified gases?

A
  • Nitrous oxide
  • Carbon dioxide
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5
Q

What government agencies are involved with compressed gases used in the OR?

A
  • FDA (purity of substance)
  • DOT (marking, labeling, storage, handling)
  • OSHA (employee safety)
  • National Fire Protection Association
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6
Q

Name the components of the cylinder:

A
  • Body
  • Valve
  • Handle
  • Pressure Relief Device
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7
Q

What is the body of the cylinder made out of?

A
  • Steel
  • Steel Carbon Fiber
  • Aluminum
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8
Q

What kind of bases do the cylinders have?

A
  • Flat Base
  • Concave Base
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9
Q

What is the valve of the cylinder made out of?

A
  • Bronze
  • Brass
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10
Q

What is the function of the valve on the cylinder?

A
  • The valve is attached to the neck of the cylinder and allows refilling and discharge of gas

O2 tanks are now refilled away from the facility.

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11
Q

What is used to open/close the cylinder?

A
  • Handle

Handles should be attached to EVERY cylinder

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12
Q

What component vents cylinder contents to the atmosphere if pressure increases to a dangerous level (overheating or filling)?

A
  • Pressure relief device

Pressure relief device can be a disc or a plug.

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13
Q

What is the Pin Index Safety System?

A
  • Pins protrude from yokes and fit corresponding holes in the cylinder valves, providing a mostly “fool-proof” way of connecting the appropriate gas to the appropriate valve.
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14
Q

How are cylinder sizes labeled?

What is the most common cylinder size on anesthesia machines?

A
  • A (smallest) to H (largest)
  • Cylinder size E on anesthesia machines
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15
Q

What size cylinders are used for transport?

A
  • Cylinder size D are used for transport
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16
Q

What is the content and pressure of a full oxygen tank on an anesthesia machine?

A
  • 600 L
  • 1900 - 2200 psi

Non-liquefied gases: Pressure decreases as volume decreases. Half the volume, Half the psi.

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17
Q

For liquefied gases, the pressure depends on ______. This makes pressure NOT an indication of remaining volume.

A
  • Vapor Pressure

Note the full and half tank of Nitrous, but tanks have a pressure of 745 psi. Pressure is not an indicator of volume for liquefied gase.

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18
Q

What are the Department of Transportation (DOT) regulations for cylinders?

A
  • Service pressure
  • Test date
  • Diamond shaped label indicating hazard of gas…danger, warning, or caution
  • Name and address of manufacturer
  • Expiration date of contents
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19
Q

Cylinder Standards: Valves, regulators, gauges never come into contact with what?

A
  • Oil
  • Grease
  • Lubricants
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20
Q

Cylinder Standards: Never subject cylinder to temps above ______

A
  • 54 C (130 F)
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21
Q

Cylinder Standards: Never cross use what?

A
  • Hoses
  • Regulators
  • Gauges
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22
Q

Cylinder Standards: What must not be altered?

A
  • Original Markings on Cylinder
  • Original Labels
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23
Q

Associate the color with gas:
Green
Blue
Yellow
White

A
  • Green = Oxygen
  • Blue = Nitrous
  • Yellow = Air
  • White = Suction
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24
Q

Describe the conditions of storage rooms for cylinder tanks.

A
  • Adequate ventilation
  • “No smoking,” or “No Combustibles” signs
  • Cylinders are not exposed to corrosive chemicals, fumes
  • Stored upright in bins
  • Full tanks separated from empty tanks
  • Do not wrap or drape cylinders
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25
Q

Things to consider when using gas cylinders.

A
  • Inspect label, pin index holes, regulator, valve outlet
  • Check if tamper seal is removed
  • Check if washer is in place
  • Open the valve (slowly) to relieve excess pressure before bringing the cylinder to pt
  • Face valve outlet away from people
  • Check service pressure
  • Correct leaks
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26
Q

How do oxygen, nitrous, and air get delivered throughout the hospital?

A
  • Pipeline Systems
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27
Q

Where are possible locations for the Central Supply?

A
  • Outdoors in an enclosure
  • Indoors in secure area
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28
Q

A Central Supply “bank” must contain gas for at least how many days?

A
  • 2 days
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29
Q

What cylinder size would an oxygen bank be?

A
  • G and H cylinders
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30
Q

Differentiate between a gaseous and liquid oxygen supply source.

A
  • Gaseous oxygen supply is contained in large G/H cylinders, refilled on-site or transported
  • Liquid oxygen supply is less expensive and more convenient to store, refilled by supply trucks, service can not be interrupted
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31
Q

What are the three classes of piping?

A
  • Main lines: connect gas source to risers
  • Risers: vertical pipes connecting main line with branch lines on each level of the facility
  • Branch: sections supplying a room or group of rooms on one level of the facility
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32
Q

Permit specific areas of the piping system to be isolated for problems /maintenance.

A
  • Shut-off Valves
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33
Q

The area alarm system must be in at least how many places?

What places will have the gas alarm system?

A
  • 2 places
  • The affected unit, critical life support area, maintenance, engineering
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34
Q

The area alarm system will be triggered if pressure increases/decreases ____ % from normal.

A
  • 20%
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35
Q

Area system alarm must be ________ AND ________.

A
  • audible
  • visible
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36
Q

What are terminal units?

A
  • Point in piped gas distribution where user connects and disconnects by hose
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37
Q

What safety system does the terminal unit use?

A
  • Diameter Index Safety System (DISS)

DISS = Nipple and nut vary in bore and diameter
PISS for cylinders
DISS for wall units

38
Q

What allows convenient connection with one/both hands to terminal units?

What is the drawback to this?

A
  • Quick Connectors
  • Drawback: Quick Connectors leak more
39
Q

Where are possible locations for Quick Connects?

A
  • Wall
  • Ceiling -mounted
  • Ceiling column
40
Q

Volatile anesthetics exist in a liquid state below what temperature?

A
  • 20C (68F)
41
Q

In a closed container, molecules escape liquid to __________ phase.

A
  • Vapor
42
Q

What is saturated vapor pressure (SVP)?

A
  • When vapor molecules bombard a closed container until it has reached an equilibrium of the liquid’s surface.
  • Gas phase above liquid contains all the vapor it can hold
43
Q

State Dalton’s Law

A
  • Sum of Partial Pressure = Total Pressure
  • Part of the total pressure of any one gas in a mixture
44
Q

Partial pressure is dependent on _______.

A
  • Temperature
45
Q

The concentration of a gas in a mixture expressed as a percentage

A
  • Volume percent
46
Q

Partial Pressure / Total Pressure =

A
  • Volume percent
47
Q

Vapor pressure is independent of _______

A
  • Atmospheric Pressure (Barometric Pressure)
48
Q

Vapor pressure is dependent on ________

A
  • Characteristics of liquid
  • Temperature of liquid
49
Q

Vapor Pressure of Halothane (Fluothane)

A
  • 243 mmHg
50
Q

Vapor Pressure of Enflurane (Ethrane)

A
  • 175 mmHg
51
Q

Vapor Pressure of Isoflurane (Forane)

A
  • 238 mmHg
52
Q

Vapor Pressure of Desflurane (Suprane)

A
  • 669 mmHg
53
Q

Vapor Pressure of Sevoflurane (Ultane)

A
  • 157 mmHg
54
Q

The temperature at which vapor pressure equals to atmospheric pressure.

A
  • Boiling point
55
Q

Which volatile anesthetic has a vapor pressure almost equal to atmospheric pressure?

A
  • Desflurane (Suprane)
  • Boiling point of Desflurane 22.8C (73F)
56
Q

The number of calories necessary to convert 1 gram of liquid into vapor (or 1 mL of liquid to vapor).

A
  • Heat of Vaporization
57
Q

What happens to the liquid temperature and vapor pressure as carrier gas flows through the vaporizer, causing the vapor molecules to leave?

A
  • Liquid temperature drops, causing vapor pressure to drop
  • There will be an equilibrium shift, more molecules in a liquid state
  • Output of vapor will decrease

More heat will be needed to increase vapor output.
Vapor pressure is dependent on heat (temperature).

58
Q

Number of calories required to raise the temperature of 1 g of a substance 1 degree C

A
  • Specific Heat

The higher the specific heat, the more heat required to raise the temp of the substance

59
Q

Specific Heat of Water

A

The Standard

60
Q

Material with higher specific heat minimizes _________.

A
  • Temperature Variation
61
Q

The ‘speed’ at which heat flows through a substance

A
  • Thermal Conductivity

The higher the thermal conductivity, the better the substance conducts heat

62
Q

Metals with high thermal conductivity minimize ____________ during vaporization.

A
  • temperature swings

  • Copper and Aluminum have the best thermal conductivity
63
Q

A device that changes a liquid anesthetic agent to a vapor and adds a controlled amount of that vapor to fresh gas flow in the breathing system.

A
  • Vaporizer
64
Q

Modern vaporizers are _________-calibrated and variable bypass.

A
  • Concentration
65
Q

Where is the vaporizer located?

A
  • Between flow meter and common gas outlet
66
Q

What happens if the vaporizer is before the flow meter?

What happens if the vaporizer is after the common gas outlet?

A
  • Carrier gas will be on the wrong side and will not be able to pick up adequate vapor molecules
  • There will be less stability and flow of vapor molecules delivered to the patient
67
Q

What regulates the concentration of the volatile in the vaporizer (variable bypass)?

A
  • The concentration dial
68
Q

What makes up the splitting ratio?

A
  • Vaporizing chamber flow rate
  • By pass pathway flow rate

Higher splitting ratio means more flow will go through vaporizing chamber, higher anesthetic gas delivery.

69
Q

What are the two types of vaporizers?

A
  • Flow-over (modern)
  • Bubble through (older)
70
Q

Why is desflurane heated in the vaporizer when its boiling point is at room temperature?

A
  • There is a lot of variability at room temperature.
  • Desflurane is heated to a precisely controlled temperature and stable vapor phase.
  • The heated vapor is then “injected” into the fresh gas flow to deliver a precise anesthetic concentration.
71
Q

What factors can influence vaporizer output?

A
  • Placing incorrect agent in the vaporizer
  • Flow Rate
  • Pumping Effect
  • Effects of Rebreathing
  • Barometric Pressure
  • Tipping
  • Overfilling
  • Leaks
72
Q

Why is placing the incorrect volatile agent in the vaporizer unlikely?

A
  • Filling systems are agent-specific
73
Q

How do you fix this issue if you somehow get the wrong agent in the vaporizer?

A
  • Vaporizer must be completely drained, and all liquid discarded
  • Run FGF at 8-10 L/min until no vapor is detected

The monitor will detect 2 vapors if incrorect agent is added to the vaporizer

74
Q

What happens to the vaporizer output if the flow rate is less than 250 ml/min?

A
  • Output will be less than setting
  • High density of volatile prevents upward movement of molecules
75
Q

What happens to the vaporizer output if the flow rate is greater than 15 L/min?

A
  • Output will be less than setting
  • Failure to saturate carrier gas because the carrier gas is too fast.
76
Q

What are two common causes of the anesthesia machine’s intermittent back pressure (pumping effect)?

A
  • Positive Pressure Ventilation
  • Oxygen Flush Valve
77
Q

The pumping effect is more pronounced with:

A
  • Low flow rates
  • Low dial settings
  • Low levels of liquid in the vaporizing chamber
78
Q

What problem does the pumping effect have on vaporizer output?

A
  • Inconsistency in maintaining alveolar pressure of anesthetic vapors

Negate the pumping effect by maintain adequate flow rate and dial setting

79
Q

What object in the anesthesia machine counters the pumping effect?

A
  • Machine Outlet Check Valve
80
Q

What are measures to attenuate the pumping effect besides the machine outlet check valve?

A
  • Smaller vaporizing chamber
  • Baffle system
  • Longer tube for the inlet of the vaporizing chamber
81
Q

Effects of rebreathing with high FGF

Effects of rebreathing with low FGF

A
  • Little exhaled gas rebreathed
  • Significant rebreathing with low FGF
82
Q

Vaporizers are calculated at __________

A
  • sea level (760 mmHg)
83
Q

Why will an increase in altitude not affect the delivery of Isoflurane or Sevoflurane?

A
  • Isoflurane and Sevoflurane are not pressurized. They operate as a function of atmospheric pressure.
  • At sea level, atm = 760 mmHg. This pressure keeps molecules down in the liquid phase.
  • So, in higher elevations, there will be less atmospheric pressure. Which means more molecules can escape as a gas.
  • The decrease in atmospheric pressure and the increase in the volume percent of gas will equal the partial pressure of gas delivered at sea level.
  • Refer to the math below or watch the YouTube link.
  • https://www.youtube.com/watch?v=UgViWCNVgOA&ab_channel=CountBackwardsFrom10
84
Q

How does tipping affect vaporizer output?

A
  • There will be an excessively high output due to liquid entering the bypass chamber
85
Q

Vaporizer leaks can be caused by:

A
  • Loose filler caps
  • Drain valves
  • Vaporizer/mounting bracket interface
86
Q

What would be indicators of vaporizer leaks?

A
  • Odor of gas
  • Lower than expected inhaled concentration
87
Q

What will be the patient consequence of a vaporizer leak?

A
  • Patient awareness
88
Q

What are vaporizer safety standards?

A
  • Average concentrations +/- 20% of setting
  • Gas may not pass through more than 1 vaporizer
  • Output of vaporizer <0.05% in OFF
  • All control knobs counterclockwise
  • Filling levels displayed
  • Can’t overfill when in use
89
Q

What are the mounting standards of the vaporizer?

A
  • Detachable
  • Weight of vaporizer and “O” ring creates seal
  • Locking lever on the back
  • Easily removed and replaced (especially for MH)
90
Q

What prevents more than 1 vaporizer from being turned on at a time?

A
  • Interlock Device

JW: Principles of Anesthesia I (61 decks)

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