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1principles of anesthesia > Breathing Systems Pt2 (Exam 2) > Flashcards

Breathing Systems Pt2 (Exam 2) Flashcards

1
Q

A unidirectional valve is broken. Is the attached inspiratory limb considered dead space?

A

Yes, now bidirectional gas flow is occurring. If valve is fixed then the limb will not be considered dead space again.

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2
Q

What shape do breathing/reservoir bags have? Why?

A

Ellipsoidal for 1 hand ventilation

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3
Q

What volume do breathing bags have?

A

3L for adults

(0.5 - 6L range)

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4
Q

What is the minimum pressure of a breathing reservoir bag?

A

30 cmH₂O

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5
Q

What is the max pressure of breathing reservoir bags?

A

40 - 60 cmH₂O

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6
Q

____ bags have 2x the distending pressure of ____ bags.

A

Plastic bags have 2x the distending pressure of rubber bags.

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7
Q

What functions does the breathing/reservoir bag serve? (5)

A
  • Reservoir for gasses & O₂
  • Manual ventilation
  • Assistance w/ spontaneous ventilation
  • Protection from excessive positive pressure
  • Visual/tactile monitoring of ventilation
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8
Q

Where is the preferred location for the fresh gas inlet?

A

Between CO₂ absorbent and inspiratory valve

located near each

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9
Q

What is the purpose of the APL (adjustable pressure limiting) Valve?

A

Pop-off valve
- Permits gas to leave the circuit to the scavenging system
- Controls pressure in the breathing system

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10
Q

Turning the APL valve in a clockwise motion will ______ pressure.

A

increase pressure

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11
Q

Turning the APL valve in a counterclockwise motion will ______ pressure.

A

decrease pressure

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12
Q

How many turn are required to go from fully open to fully closed on the APL valve?

A

1-2 clockwise turns

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13
Q

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

A

Returns gas to the patient

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14
Q

What is the chemical formula for soda lime?

A

Ca(OH)₂

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15
Q

What is the chemical reaction that occurs with soda lime in a CO₂ absorbent cannister?

A

CO₂ + Ca(OH)₂ → CaCO₃ + H₂O + heat

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16
Q

What are the components of soda lime?

A
  • Calcium hydroxide (80%)
  • Sodium & potassium hydroxide (5%)
  • Water (15%)
    -Small amount of silica and clay
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17
Q

When does soda lime become exhausted?

A

When all hydroxides become carbonates

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18
Q

How much CO₂ can soda lime absorb?

A

19% of its weight

100g can absorb 26L of CO₂

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19
Q

What absorbent has greater absorption capacity and is used in submarines and spacecraft?

A

Lithium Hydroxide

20
Q

Which absorbent is responsible for compound A, CO formation and destruction of inhaled gases?

A

Calcium Hydroxide Lime

21
Q

What is Litholyme?

A

Lithium chloride catalyst

22
Q

What are the benefits of Litholyme (Lithium chloride) ?

A
  • No compound A formation
  • No reaction with inhaled anesthetic agents
  • Low exothermic reactivity, and low risk of fire
  • Better for environment
23
Q

What absorbent has no color indicator?

A

Spira-Lith (Anhydrous LiOH with polymer sheet)

24
Q

What are the benefits of Spira-Lith?

A
  • Large reaction surface area
  • ↓ temperature production
  • Long duration
  • Cost effective
    -no activators/strong bases
25
Q

At what pH do absorbents undergo color change?

A

<10.3

pH > 10.3 (absorbent is colorless & fresh)
pH < 10.3 (exhausted & purple absorbent)

26
Q

What dyes are used in CO₂ absorbents?

A
  • Ethyl Violet (most common)
  • Ethyl orange
  • Cresyl yellow
27
Q

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

A

Maximize absorption and minimize resistance

28
Q

What will excess liquid water do inside a CO₂ absorbent cannister?

A
  • ↓ surface area
  • ↓ absorbent efficiency
29
Q

Approximately how much of a CO₂ absorbent cannister’s volume is gas?

A

½

30
Q

What is channeling and its consequence?

A
  • Small passage ways allowing gas to flow through low resistance areas
  • Decreases functional absorptive capacity
31
Q

How can channeling be minimized? (5)

A
  • Circular baffles (tube)
  • Permanent mounting
  • Vertical flow
  • Prepackaged cylinders
  • Avoiding over packing
32
Q

Which gasses produced the most CO?
The least?

A

Desflurane ≥ Enflurane > Isoflurane > Halothane > Sevo

33
Q

Why should sevoflurane use with dessicated strong base absorbents (baralyme, LiOH) be avoided?

A

High risk of fire

34
Q

What is required for unidirectional valves? (5)

A
  • arrows or directional words
  • hydrophobic
  • appropriate open/closing
  • clear dome
  • placed between pt and reservoir bag
35
Q

Label the following APL valve

A
36
Q

With spontaneous ventilation, what occurs to the APL valve during inspiration? Expiration?

A

Inspiration: APL valve closed
-Partially closed for CPAP

Expiration: APL valve open

37
Q

With assisted/manual ventilation, what occurs to the APL valve during inspiration? Expiration?

A

Inspiration: APL partially open for excess diversion

Expiration: APL partially open

38
Q

When mechanical ventilation, what occurs to the APL valve during inspiration? Expiration?

A

Both bypass the APL

39
Q

What is the purpose of valves in the absorber housing?

A

valves close when canister is removed to prevent gas loss

40
Q

What are the components of Calcium Hydroxide Lime (amsorb)?

A
  • Calcium Hydroxide (70%)
  • Calcium chloride (0.7%)
  • Calcium sulfate (0.7%)
  • Polyvinylpyrrolidone (0.7%)
  • Water(14.5%)
41
Q

Decomposition of sevoflurane is presumed to form ____? What is the potential consequence of this formation?

A

Compound A

Potential nephrotoxin in humans (nephrotoxic to rodents)

42
Q

Formation of compound A is thought to occur d/t?

A
  • low FGF
  • ↑absorbant temperatures
  • ↑inspired sevo concentrations
  • dessicated absorbant (dried out)
43
Q

Dessicated absorbant, potentially produces what? (2)

A
  • Compound A
  • Carbon monoxide
44
Q

Do pulse ox or IR gas monitors pick up CO?

A
  • Pulse ox does, but doesn’t distinguish from O₂
  • IR gas monitors don’t pick up
45
Q

How high can temperatures reach in dessicated CO₂ absorbers?

A

can exceed 200 ⁰C (392 ºF)

46
Q

What are flammable degradation products to consider with absorbents? What else can contribute to combustion of absorbent?

A
  • formaldehyde
  • methanol
  • formic acid

O₂ or nitrous rich gases

47
Q

What can be done to prevent fires/combustion of absorbent?

A
  • turn off gas flows after each case to prevent dessication
  • change absorbent regularly and when exhausted
    -change both canisters (2 canister system)
  • change compact canisters more frequently

1principles of anesthesia (26 decks)

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