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Principles > Breathing systems > Flashcards

Breathing systems Flashcards

1
Q

Desirable Characteristics of A Breathing Circuit

A

Low resistance to gas flow
Minimal rebreathing
Removal of CO2 at rate of production
Rapid changes in delivered gas when required
Warmed humidification of inspired gas
Safe disposal of waste gases

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2
Q

No reservoir bag and no rebreathing circuits

A

Open

nasal cannula, open drop ether
no valves or tubing.

systems have no valves, no tubing: for example open drop ether, or a nasal cannula. In either, the patient has access to atmospheric gases.

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3
Q

Reservoir bag but no rebreathing circuits

A

Semi-open
(no rebreathing, high fresh gas flow [higher than minute ventilation])

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4
Q

Reservoir bag and partial rebreathing circuits

A

Semi-closed

(some rebreathing occurs, FGF andAPL settings at intermediate values)

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5
Q

Reservoir bag and complete rebreathing circuits

A

Closed

Depends on FGF

(fresh gas inflow exactly equal to patient uptake, complete rebreathing after carbon dioxide absorbed, andAPL closed)

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6
Q

Circle systems

A

closed, semi closed, semi open

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7
Q

Mask requirements

A

inflatable (Pneumatic cushion that seals to face)
clear

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8
Q

Proper mask fit size/position

A

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

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9
Q

Masks connect to…..

A

Connect to the Y-piece or connector with a 22 mm female connection

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10
Q

A fitting that joins together 2 or more components

A

Connectors/Adapters

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11
Q

Benefits of connectors/adapters

A

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

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12
Q

Disadvantages of connectors/ adapters

A

Increased resistance
Increases dead space
Additional locations for disconnects

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13
Q

Breathing Tubing length and internal volume

A

1 meter in length
Internal volume - 400-500 mL/m of length (makes distensible)

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14
Q

Breathing tubing air flow is always_______

A

Flow always turbulent due to corrugation

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15
Q

Places for bidirectional gas flow

A

lma, y piece

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15
Q

Dead space only from

A

Dead space only from Y piece to patient d/t unidirectional gas flow

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16
Q

Breathing tubing pressure check using….

A

Pressure check circuits before use
Hold pressure at 30 cm H2O

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17
Q

Unidirectional valves disks eith____

A

Disks with knife edges, rubber flaps, or sleeves

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18
Q

Direct respiratory gas flow in the correct direction

A

unidirectional Valves

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19
Q

Unidirectional valves have _____ resistance and ______ competence

A

Low resistance and high competence

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20
Q

Failure for unidirectional valves to seal causes a large amount of the circuit to become _______

A

appartatus dead space

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21
Q

Opens on inspiration and closes on exhalation
Prevents backflow of exhaled gas

A

Inspiratory valve

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22
Q

Opens on exhalation and closes on inspiration
Prevents rebreathing

A

Expiratory valve

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23
Q

What is Apparatus dead space

A

Distal limb of the Y-connector
Tube/mask

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24
Q

Proper valve placement and functioning prevents any part of the circle system from contributing to _______

A

apparatus dead space

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25
Q

Unidirectional Valves are located near ________

A

Valves are located near CO2 absorber canister casing, fresh gas inflow site, and the pop-off valve

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26
Q

Unidirectional valves requirements

A

Arrows or directional words
Hydrophobic
Must open and close appropriately
Clear dome
Must be placed between pt and reservoir bag

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27
Q

Breathing/Reservoir Bags volume

A

3L traditional for adults
0.5 - 6L

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28
Q

Breathing/Reservoir Bags must have _____ connector on the neck

A

Must have 22 mm female connector on neck

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29
Q

Breathing / reservoir bags minimum and max pressure

A

Minimum pressure 30 cm H2O
Max pressure 40 - 60 cm H2O (rubber bags)

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30
Q

Breathing/Reservoir Plastic Bags vs Rubber bags

A

Plastic bags – 2x the distending pressure of rubber bags

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31
Q

Reservoir bag shape

A

Ellipsoidal for 1 hand ventilation

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32
Q

Permits gas to leave the circuit. Controls pressure in breathing system

A

Adjustable Pressure-Limiting Valve (APL)

Tightened screw cap, more gas pressure is required to open it

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33
Q

Gases are delivered from the common gas outlet to the circuit.

A

Gas Inflow Site

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34
Q

APL valve other name

A

Pop-off valve

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35
Q

Gas Inflow Site located______

A

Located near the inspiratory unidirectional valve or CO2 absorbent canister housing in circle systems

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36
Q

Gas Inflow Site preferred location

A

between CO2 absorbent and inspiratory valve

Other locations for other circuits depends on whether breathing is spontaneous, assisted, or controlled because the type of breathing influences the efficiency of carbon dioxide elimination.

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37
Q

A reservoir function is necessary because _____

A

anesthesia machines cannot provide the peak inspiratory gas flow needed during normal spontaneous inspiration solely from fresh gas flow.

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38
Q

APL releases gas to_____

A

Releases gases to scavenging system

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39
Q

Adjustable Pressure-Limiting Valve (APL) adds ____ during spontaneous ventilation or pressure-limited controlled respiration

A

PEEP

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40
Q

APL rotation requirements

A

Clockwise motion increases pressure (closes valve)
Opposite motion decreases pressure (opens valve)
1-2 clockwise turns from fully open to fully closed
An arrow must indicate direction to close valve

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41
Q

incorporates valves that closes when the canister is removed to prevent gas loss

A

housing for absorber canister

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42
Q

What does the Side/center tube in an absorber canister do?

A

returns the gas to the pt

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43
Q

Soda lime components

A

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

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44
Q

Soda lime activators/ strong bases

A

Sodium hydroxide and potassium hydroxide (~5%)

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45
Q

Soda lime is exhausted when……

A

all hydroxides become carbonates

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46
Q

Soda lime chemical reaction

A

CO2 + Ca(OH)2 = CaCO3 + H2O + heat

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47
Q

Soda lime absorbents can absorb _______ in CO2

A

19% of its weight in CO2

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48
Q

100 g can of sodal lime can absorb approximately ______ CO2

A

26L

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49
Q

Calcium hydroxide lime components

A

Calcium hydroxide (70%)
Calcium chloride (0.7%)
Calcium sulfate (0.7%)
Polyvinylpyrrolidone (0.7%)
Water (14.5%)

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50
Q

Another name for Calcium hydroxide lime and benefits

A

ansorb

decrease productions of; compounds A and CO and Destruction of inhaled gases

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51
Q

APL releases gas to_____

A

Releases gases to scavenging system

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51
Q

Adjustable Pressure-Limiting Valve (APL) adds ____ during spontaneous ventilation or pressure-limited controlled respiration

A

PEEP

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52
Q

Absorbent that Reacts with CO2 to form carbonate

A

lithium hydroxide

More CO2 absorption capacity

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53
Q

absorbents used in Used in submarines and spacecrafts

A

lithium hydroxide

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54
Q

Absorbent with No activators/strong bases

A

Litholyme

Does not form compound A and CO
reaction with inhaled anesthetic agents

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55
Q

absorbent with pH indicators do not become colorless

A

litholyme
No regeneration
pH indicators do not become colorless

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56
Q

Absorbent with Lower exothermic reactivity, reduced risk of fire, and reduced economic/environmental impact

A

Litholyme

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57
Q

Absorbent with Anhydrous LiOH powder within a nongranular partially hydrated polymer sheet

A

Spira-Lith

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58
Q

Spira-Lith features

A

-Larger surface area for reaction
-No activators/strong bases
-Reduced temperature production
-Longer duration of use
-Cost-effective
-No color indicator

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59
Q

What is the most common dye for absorbent indicators

A

Ethyl violet is the most common dye
Ethyl orange, cresyl yellow

60
Q

Absorbent Indicators Undergoes color change around pH

A

pH of 10.3

61
Q

Absorbent Indicators Carbonate formation

A

pH becomes less alkaline
White to blue violet

62
Q

Fresh absorbent is_____ and is at a pH_____

A

Fresh absorbent is colorless, pH > 10.3

63
Q

Exhausted absorbent is _____, pH ______

A

Exhausted absorbent is purple, pH < 10.3

64
Q

Gold standard for Absorbent Indicators reliability

A

capnometry

Regeneration- Color fading

65
Q

Half volume of absorbant cannister is _____

A

gas

66
Q

mesh size

A

4-8

67
Q

Excess liquid water within the absorbent canister decreases

A

Excess liquid water within canister decreases surface area and efficiency of CO2 absorption

68
Q

Small passage ways allowing gas to flow through low-resistance areas

A

channeling in co2 absorber

Decreases functional absorptive capacity

69
Q

channeling Minimized by

A

Circular baffles
Placement for vertical flow
Permanent mounting
Prepackaged cylinders
Avoiding overly tight packing

70
Q

Compound A name

A

2-fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether

71
Q

Low FGF, Increased absorbent temperature, Higher inspired sevoflurane concentrations, and Dehydrated absorbent causes what?

A

Compound A formation

72
Q

Rank inhalants highest to lowest levels of CO formation

A

Desflurane ≥ enflurane > isoflurane&raquo_space; halothane = sevoflurane

73
Q

Carboxyhemoglobin levels >________

A

levels >35%
Pulse ox or IR gas monitors wont pick it up

74
Q

Risk of formation of CO with______

A

Increased temperatures
Increased concentrations of anesthetic gases
Low FGF rates
Smaller pt size
Strong base absorbents

75
Q

APL releases gas to_____

A

Releases gases to scavenging system

76
Q

Adjustable Pressure-Limiting Valve (APL) adds ____ during spontaneous ventilation or pressure-limited controlled respiration

A

PEEP

77
Q

Exothermic reactions, leading to fires and explosions

A

Absorbent Heat Production

78
Q

Baralyme, anhydrous LiOH risk

A

Desiccated strong base absorbents interact with sevoflurane

Absorbers exceed 200 degrees Celsius (392 degrees Fahrenheit) and higher w/ fire in some breathing circuits

79
Q

What in absorbers can cause combustion

A

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

Avoid sevoflurane use with desiccated strong base absorbents

80
Q
A
81
Q
A
82
Q

components of Mapleson circuits

A

Reservoir bag
Corrugated tubing
APL valve
Fresh gas inlet
Patient connection

83
Q

What does the mapleson circuit not hve?

A

CO2 absorber
Unidirectional valves
Separate inspiratory and expiratory limbs

84
Q

Other name for mapleson circuit

A

Also called, carbon dioxide washout circuits or flow-controlled breathing systems

85
Q

Because there is no clear separation of inspired and expired gases with maleson circuits, rebreathing will occur when the ________.

A

inspiratory flow exceeds the fresh gas flow.

86
Q

Best efficiency of all systems for spontaneous ventilation, worst during controlled ventilation

A

Mapleson A (Magill’s system)

87
Q

Rebreathing with magills system during controlled ventilation occurs unless __________

A

minute ventilation is very high, more than 20L/min

88
Q

why is Mapleson B innefficient

A

Much of FGF is vented through APL during exhalation

FGF should be 2x minute volume during spontaneous and controlled ventilation to prevent rebreathing

89
Q

Identical to Mapleson B except corrugated tubing omitted, Almost as efficient as Mapleson A

A

Mapleson C

90
Q

The circuit used for emergency resuscitation

A

Mapleson C
FGF 2x minute volume

91
Q

Most efficient system for controlled ventilation

A

Mapleson D

92
Q

Mapleson D fgf

A

FGF 2 – 2.5x minute ventilation

93
Q

APL valve in use of Mapleson D

A

Spontaneous ventilation: Open (excess gases are vented out during expiration)
Manually controlled ventilation: Partially closed (pressure rises during inspiration due to squeezing of bag and excess gases are vented out)
Mechanically controlled ventilation: Closed (excess gases are vented through the ventilator spill valve).

94
Q

Corrugated tubing attached to the T-piece forms reservoir
No reservoir bag/No APL

A

Mapleson E (Ayre’s T-Piece)

95
Q

preferred in pediatric patients for both the spontaneous and controlled ventilation

A

Mapleson E

used in less than 20kg pts

Due to absence of APL valve, the resistance in the system is lower compared to other systems and are preferred in pediatric patients for both the spontaneous and controlled ventilation.

96
Q

Jackson-Rees modification (of Mapleson E)

A

Mapleson F (Jackson Rees)
Reservoir bag added

97
Q

Mapleson F Minute ventilation

A

2 - 2.5x minute ventilation

Excessive pressure less likely to develop
No APL valve

98
Q

Improved rebreathing with maplesons efficiency is d/t_______

A

location of the pop-off valve relative to FGF

99
Q

system with significant amounts of fresh gas is vented through pop-off at end expiration

A

B&C mapleson systems

100
Q

systems FGF drives exhaled alveolar gas away from pt

A

DEF systems

101
Q

Spont ventilation mapleson efficiency ranking

A

Mapleson A is greater than Maplesons DFE, which are greater than Maplesons CB

102
Q

Controlled vent mapleson efficiency ranking

A

Maplesons DFE are greater than Maplesons BC, which are greater than Mapleson A

103
Q

Advantages of Maplesons

A

Simple, inexpensive, and lightweight
Changes in FGF composition result in rapid changes in the circuit
Low resistance to gas flow
No toxic products d/t lack of CO2 absorbent
No degradation w/ VAs

104
Q

Disadvantages of Maplesons

A

Require high FGF
Conservation of heat and humidity low in inspired gas
Scavenging challenging
Not suitable for patients with MH

105
Q

Systems with the Exception to scavenging challenges

A

Except Mapleson D, APL valve away from pt

106
Q

Rules to prevent rebreathing with circle systems

A

-Unidirectional valve must be located between the pt and the reservoir bag on both the inspiratory and expiratory limbs
-The fresh gas inflow cannot enter thecircuitbetween the expiratory valve and the pt
-APL valve cannot be located between the pt and the inspiratory valve

107
Q

Partial rebreathing occurs but some waste flow is vented through APL or waste gas valve of ventilator

A

Circle System Function Semi-closed

108
Q

FGF is less than minute ventilation

A

low-flow anesthesia

50% of expired gas is rebreathed after CO2 removal

109
Q

Higher FGF with minimal rebreathing and more venting of waste gas

A

Circle System; Semi-open

post-op and ICU vents, scuba gear

110
Q

Rate of oxygen inflow exactly matches metabolic demand

A

Circle system; closed

Rebreathing is complete
No waste gas is vented
VAs are added to circuit in liquid form in precise amounts or through the vaporizer
Low- and minimal-flow anesthesia

111
Q

Advantages of low - flow anesthesia

A

decreased use of VAs
improved temp and humidity control
reduced environmental pollution

112
Q

Disadvantages of low flow anesthesia

A

-Difficulty in rapidly adjusting anesthetic depth
-Possibility of accumulating unwanted exhaled gases ( ex: CO, acetone, methane)
-VA degradation by-products (ex: CO, compound A)

113
Q

Advantages of circle system

A

-Low FGF can be used
-Elimination of CO2
-Relatively stable inspired gas concentration
-Conservation of moisture/heat/gases
-Prevention of OR pollution

114
Q

Disadvantages of circle systems

A

-Complex design
-CO or compound A
May compromise Vt during controlled ventilation
-ASA Closed Claims Project; Misconnections/ disconnections

115
Q

Components of self- inflating manual resuscitators

A

-Self-expanding Bag
-T-shaped non-rebreathing Valve
-Bag Inlet Valve
-Pop-off valve
-Excess oxygen venting valve
-Oxygen reservoir

116
Q

Uses of self inflating manual resiscitators

A

Hand ventilation in the absence of an oxygen or air source
Pt transport
CPR
Emergency back-up

117
Q

Hazards with self inflating manual resiscitators

A

Barotrauma or gastric insufflation
Significant variation of tidal volume, PIP, and PEEP
Nonrebreathing valves generate resistance

118
Q

Effective preventing contamination anesthesia machine from airborne diseases

A

Bacterial Filters

119
Q

Bacterial filters are placed on_____

A

Placed on the expiratory limb

120
Q

Amount of water vapor in a gas

A

Humidity

121
Q

Mass of water vapor present in gas in mg H2O/L of gas

A

Absolute humidity

122
Q

Percent saturation; amount of water vapor at a particular temp

A

Relative Humidity

123
Q

Pressure exerted by water vapor in a gas mixture

A

Water Vapor Pressure

124
Q

Maximal contact of inspired gas w/ large mucosal surface area in the _______

A

nasal cavity

125
Q

Heating and humidification has occurred by ______

A

mid trachea

126
Q

mid trachea temperature

A

34°C with an absolute humidity of 34 to 38 mg/L (95% to 100% relative humidity)

127
Q

Absolute humidity of air at body temperature

A

Absolute humidity of 44 mg/L (100% relative humidity)

Isothermic saturation boundary

128
Q

Cold ambient temperatures

A

Little capacity to hold water vapor
Low absolute humidity
Upper airway transfers large amounts of heat and moisture

129
Q

Little heat energy is expended to warm inspired gases

A

Warm ambient temperatures

130
Q

Cool inspired gas may trigger ______

A

bronchospasms

131
Q

Damage that under humification has on the respiratory tract

A

Secretions thicken
Ciliary function decreases
Surfactant activity is impaired
Mucosa susceptible to injury

132
Q

Condensation of water in the airway causes…..

A

-Reduced mucosal viscosity and risk of water intoxication
-Inefficient mucociliary transport
-Airway resistance, risk of pulmonary infection, surfactant dilution, atelectasis, and V/Q mismatch
-Obstruction to sensors

133
Q

HME filter is placed______

A

Placed close to the pt, between Y piece and proximal end of ETT or LMA

134
Q

HME physiologic changes

A

Low ETCO2 reading
Increases resistance and dead space in circuit
Efficiency may be reduced with large Vt(Hydrophobic models)

135
Q

Paper or other fiber barrier coated with moisture-retaining chemicals

A

Hygroscopic HME

May have some electrostatic properties

136
Q

Filter Most efficient retaining heat and moisture

A

Hygroscopic HME

137
Q

Effects of hygroscopic HME becoming saturated

A

Increased inspiratory/expiratory resistance
Reduced heat and moisture retention efficiency

138
Q

Filter with Pleated hydrophobic membrane with small pores

A

Hydrophobic HME

139
Q

More efficient filters of pathogens

A

Hydrophobic HME

140
Q

Where are humidifiers placed

A

Placed in inspiratory limb downstream of unidirectional valve
Heated humidifiers should not be placed in expiratory limb

141
Q

Condensation from humidifier can cause what physiologic change?

A

Condensation can decrease delivered Vt

142
Q

type of active humidifier that work by passing the fresh gas flow down a tube through a water reservoir causing the gas to “bubble.” Water vapor is absorbed as the bubbles pass through the reservoir

A

Bubble humidifiers

143
Q

work by passing gas over a heated water reservoir. There are two variants: one that utilizes a wick and one that utilizes a hydrophobic membrane.

A

Passover humidifiers

144
Q

-Water is heated outside the vaporizer in counter flow humidifiers. After the water is heated, it is pumped to the top of the humidifier where it enters small diameter pores and runs down a large surface area. Gas, flowing in the opposite direction, is warmed and humidified to body temperature.

A

Counter-flow humidifiers

145
Q

utilize a plastic capsule which injects water vapor and heat directly into the inspiratory limb of the ventilator circuit just before the patient y-piece.

A

Inline vaporizer humidifiers

146
Q

Unheated humidifier cannot deliver more than

A

They cannot deliver more than about 9 mg H2O/L.
Most unheated humidifiers are disposable, bubble-through devices that are used to increase the humidity in oxygen supplied to patients via a face mask or nasal cannula

147
Q

Advantages of humidifiers

A

Can deliver saturated gas at body temp or higher
More effective than HME

148
Q
A
148
Q
A
148
Q

Disadvantages of humidifiers

A

Bulky
Potential electrical, fire hazards
Contamination, cleaning issues
Higher cost than HME
Do not offer more protection against heat loss compared to forced air warming

Principles (34 decks)

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