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Principles of Anesthesia I EXAM 2 (Summer 2024: Monte) > Exam 2 Breathing Systems: Part 1 (6/20/24) > Flashcards

Exam 2 Breathing Systems: Part 1 (6/20/24) Flashcards

1
Q

Six Definitions of a Breathing System:

A
  1. Receives gas mixture from the machine
  2. Delivers gas to the patient
  3. Removes CO2
  4. Provides heating and humidification of the gas mixture
  5. Allows spontaneous, assisted, or controlled respiration
  6. Provides gas sampling, measures airway pressure, and monitors volume
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2
Q

When gas is passing through a tube, where will the pressure be the highest?

A

the pressure at the inlet will be higher than at the outlet

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3
Q

Describe Laminar Flow

A

Flow is smooth and orderly
Particles move parallel to the tube walls
Flow is fastest in the center where there is less friction

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4
Q

True or False:
In laminar flow, the flow rate is the same across the diameter of the tube?

A

FALSE!

Flow is fastest in the center where there is less friction

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5
Q

Which Law is used to describe Laminar Flow?

A

Poiseuille’s Law

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6
Q

What type of flow is this?

A

Laminar Flow

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7
Q

What type of flow?

A

Localized Turbulent Flow

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8
Q

What type of flow is this?

A

Localized Turbulent Flow

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9
Q

What type of flow is this?

A

Generalized Turbulent Flow

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10
Q

What is the name given if the particles are moving across or opposite the general direction of flow ?

A

“Eddies”

Turbulent Flow

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11
Q

In turbulent flow, is the flow rate the same or does it differ across the diameter of the tube?

A

Flow rate is same across diameter of tube

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12
Q

Describe Generalized Turbulent Flow:

A

When the flow of gas through a tube exceeds the critical flow rate

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13
Q

Describe Localized Turbulent Flow

A

Gas flow rate below the critical flow rate but encounters constrictions, curves, or valves

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14
Q

To minimize resistance, gas-conducting pathways should have ___

A
  • minimal length
  • maximal internal diameter
  • be without sharp curves or sudden changes in diameter
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15
Q

Changes in resistance ___ changes in the work of breathing

A

Parallel

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16
Q

What is one example of something that causes more resistance than the breathing system?

A

ET Tube

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17
Q

What is compliance?
What does it measure?

A

Ratio of the change in volume over the change in pressure.

Measures Distensibility (ml/cm H2O)

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18
Q

What are the most distensible components of our breathing system?

A

Breathing Tubes (Corrugated Tubing)
Reservoir Bags

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19
Q

Compliance can help determine the patient’s ___.

A

Tidal Volume

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20
Q

To inhale previously inspired gases from which CO2 may or may not have been removed:

A

Rebreathing

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21
Q

What is Rebreathing influenced by?

A
  • Fresh gas flow (High vs Low)
  • Dead space
  • Breathing system design (Semi, Closed, Open)
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22
Q

Amount of rebreathing varies ___ with the ___.

A

Inversely
total FGF

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23
Q

Will rebreathing occur or not?
Patient’s Minute ventilation is 5L/min and the FGF is 6L/min:

A

NO! The FGF is greater than the patient’s minute volume.

So long as exhaled gas is vented (not a closed system)

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24
Q

Will rebreathing occur or not?
Patient’s Minute ventilation is 6L/min and the FGF is 6L/min:

A

NO! The FGF is equal to the patient’s minute volume.

So long as exhaled gas is vented (not a closed system)

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25
Q

Will rebreathing occur or not?
Patient’s Minute ventilation is 6L/min and the FGF is 4L/min:

A

YES! The patient’s minute volume is greater than the FGF rate.

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26
Q

Will rebreathing occur or not?
Patient’s tidal volume is 600 mls and has a respiratory rate of 10 breaths per minute. The FGF is at 5L/min.

A

YES! The patient’s minute volume is greater than the FGF rate.

Minute volume = (Vt) x (RR per min)

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27
Q

True or False:
Some of the exhaled gases must be rebreathed to make up required volume

A

TRUE

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28
Q

Define Apparatus Dead Space:
Examples?

A

Volume in a breathing system occupied by gases that are rebreathed without change in composition

Ex: ETT, Face Mask, anything distal to Y-Piece

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29
Q

How can we decrease the amount of Apparatus Dead space?

A

by having inspiratory and expiratory limb separation as close to patient as possible

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30
Q

Summation of anatomical and alveolar dead spaces equals…

A

Physiologic Dead Space

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31
Q

Define Anatomical Dead space:

A

amount in the conducting airways; adds H2O vapor

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32
Q

2 Things that rebreathing reduces:

A
  1. Heat loss
  2. Moisture loss
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33
Q

Six desirable characteristics of a Breathing Circuit:

A
  1. Low resistance to gas flow
  2. Minimal Rebreathing
  3. Removal of CO2 at the same rate of production
  4. Rapid changes in delivered gas when required
  5. Warmed humidification of inspired gas
  6. Safe disposal of waste gases
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34
Q

Describe an Open Circuit:
Example?

A

No reservoir bag and no rebreathing.

Ex. Nasal Cannula

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35
Q

Patient’s minute ventilation is 4L/min and the FGF is 6L/min, what kind of circuit are we likely dealing with?

A

Semi-Open:

Reservoir bag but no rebreathing.

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36
Q

Describe a Semi-Closed circuit:

A

Reservoir bag and partial rebreathing

37
Q

In a closed circuit, if the FGF is equal or less than the patient’s minute ventilation, what will occur?

A

Rebreathing

38
Q

A pop-off valve leading to the ____ is a required component to a breathing circuit.

A

scavenging system

39
Q

Where (in great detail) should the mask fit on a patient’s face?

A

Between the interpupillary line and in the groove between the mental process and the alveolar ridge

40
Q

Benefits to using connectors/adapters:

A
  • Extends distance between patient and breathing system
  • Change angle of connection
  • Allow more flexibility/less kinking
41
Q

Disadvantages to using connectors/adapters:

A
  • Increased resistance
  • Increases dead space
  • Additional locations for disconnects
42
Q

Which of the following is NOT used to describe the breathing tubing?
A. Large Bore
B. High Resistance
C. Corrugated
D. Plastic
E. Expandable

A

B. High Resistance

The breathing tubing should have low resistance and be somewhat distensible.

43
Q

Length and internal volume of breathing tubing:

A

1 meter in length
400-500 ml/m

44
Q

How is the flow through the breathing tubing classified?
Why?

A

Flow is always turbulent due to the corrugation!

45
Q

Generally, does adding longer tubes increase dead space?
Why or why not?

A

NO! Dead space is only from the Y piece to patient and not in the tubing itself because of the unidirectional gas flow valves.

46
Q

Is there ever an example in which the tubes could increase/contribute to dead space?

A

Yes, If the unidirectional Valves are closed/not working, they CAN contribute to dead space

47
Q

If the unidirectional valves are unable to close completely and rapidly with no backflow, what can occur?

A

An increase in Apparatus dead space

48
Q

The inspiratory unidirectional valve prevents:
The expiratory unidirectional valve prevents:

A

Inspiratory: Prevents backflow of exhaled gas

Expiratory: Prevents rebreathing

49
Q

Although the unidirectional valves can be mounted anywhere between the inspiratory and expiratory limbs, these are the typical places in which they are located:

A
  • CO2 Absorber canister casing
  • Fresh gas inflow site
  • Pop-off (APL) valve
50
Q

5 requirements for the unidirectional valves:

A
  1. Arrows or directional words
  2. Hydrophobic
  3. Must open and close appropriately
  4. Clear dome
  5. Must be placed between pt and reservoir bag
51
Q

Traditionally the reservoir bags are ___ for adults but can range from ___ to ___.

A

3L
0.5L - 6L

52
Q

Minimum and Maximum pressures for the breathing/reservoir bags.

A

Min: 30 cm H2O
Max: 40-60 cm H2O

53
Q

Describe the distending pressure difference between plastic bags and rubber bags:

A

Plastic bags have 2x the distending pressure as the rubber bags

54
Q

Describe some of the functions of the reservoir bag:

A
  1. Reservoir for anesthetic gas and O2
  2. A way to manual ventilate
  3. Assists with spontaneous ventilation
  4. Protection from excessive positive pressure
55
Q

Another name for the Gas inflow site is:

A

Fresh gas inlet

56
Q

Preferred location of the gas inflow site:

A

between CO2 absorbent and inspiratory valve

57
Q

The ___ permits gas to leave the circuit.

A

APL Valve or Pop-off valve

58
Q

Turning the APL valve in a clockwise motion will do what?

A

Increase the pressure

59
Q

How many clockwise turns does it take to fully close the APL valve if it is fully open?

A

1-2

60
Q

When is the APL valve open, closed or partially closed during spontaneous respiration?

A

Closed during Inspiration
Open during Expiration
Partially closed during inspiration with CPAP

61
Q

The APL valve will be partially open during both inspiration and expiration during what type of ventilation?

A

Assisted/Manual Ventilation

62
Q

APL use during mechanical ventilation?

A

Completely bypassed during both inspiration and expiration.

63
Q

Prior to using an absorber canister we need to make sure to…

A

Remove the wrap!!

64
Q

If we are needing to change out the absorber in the middle of a case, are we able to do that? Or do we have to wait until the end of the procedure?

A

You can change it in the middle of the case if necessary. The housing of the absorber incorporates valves that close when the canister is removed to prevent gas loss.

65
Q

What is the purpose of the side/center tube located in the absorbent cannister?

A

Returns the gas to the patient

66
Q

What kind of reaction occurs that causes our CO2 absorbers to become exhausted?

A

Exothermic Chemical reaction

Once exhausted, Carbonates are formed

67
Q

Describe the components of soda lime:

A
  • Calcium hydroxide (~80%)
  • Sodium hydroxide and potassium hydroxide (~5%)
  • Water (~15%)
  • Small amounts of silica and clay
68
Q

When does the soda lime become exhausted?

A

when all hydroxides become carbonates

69
Q

Which components of the soda lime absorbent was thought to cause compound A and carbon monoxide?

A

Potassium and Sodium hydroxide

Sevo: Compound A / Des: Carbon Monoxide

70
Q

Soda lime can absorb ___ of its weight in ___.

A

19%
CO2

71
Q

100 g of Soda lime can absorb about ___.

A

26 L of CO2

72
Q

Which absorbent excludes both K and Na hydroxide in its makeup?

A

Calcium hydroxide lime (Amsorb)

73
Q

Where is the Lithium hydroxide absorbent used?

A

Submarines and Spacecrafts

74
Q

This absorbent does not have “regeneration”

What does this mean?

A

Litholyme

This means the pH indicators will not revert back to being colorless after becoming exhausted. (Soda lime has regeneration)

75
Q

Describe the Spira-Lith absorbent:

A
  • Non-granular
  • Larger surface area
  • Reduced temperature production
  • Longer Duration of use
  • No color indicator
76
Q

Because the spira-lith has no color indicator, how would we know it is becoming exhausted?

A

Capnography

The patient’s baseline would continue to rise over time

77
Q

Which dye is the most common absorbent indicator?

A

Ethyl Violet

78
Q

As carbonates are forming, what color change occurs?

A

White to a blu-ish violet

79
Q

At what pH does the absorbent undergo the color change?

A

around 10.3 and below

80
Q

What is the purpose of the mesh located in CO₂ absorbents?

A

Maximize absorption and minimize resistance

81
Q

Channeling is when there are small passage-ways that allow gas to:
What does channeling decrease?

A

Flow through-low-resistance areas

Channeling decreases functional absorptive capacity

82
Q

Channeling can be minimized by:

A
  • Circular baffles
  • Placement for vertical flow
  • Permanent mounting
  • Prepackaged cylinders
  • Avoiding overly tight packing
83
Q

Which of the following pictures is an example of channeling?

A
84
Q

Compound A formation theoretically occurs with these 4 things:

A
  1. Low FGF
  2. Increased absorbent temperature
  3. Higher inspired sevoflurane concentrations
  4. Dehydrated absorbent
85
Q

Desiccated strong base absorbents interact with ___.

A

Sevoflurane

86
Q

Select All that Apply:

A buildup of these 3 flammable degradation products within the absorber provide a basis for combustion.

A. Formaldehyde
B. Sulfuric Acid
C. Methanol
D. Polyvinylpyrrolidone
E. Silica
F. Formic Acid

A

A. Formaldehyde
C. Methanol
F. Formic Acid

Rationale: Buildup of high temperatures, flammable degradation products (formaldehyde, methanol, and formic acid), and oxygen or nitrous rich gases w/in the absorber all provide basis for combustion

87
Q

With which anesthetic gas was carbon monoxide most commonly occuring?

A

Desflurane

88
Q

Per the APSF recommendations, if we are using a 2 canister system…

A

Change them both

89
Q

True or False:
Compact canisters do not need as frequent changing as regular canisters.

A

FALSE

Principles of Anesthesia I EXAM 2 (Summer 2024: Monte) (6 decks)

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