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Topics of Respiratory Care > Ch. 3 How a Breath is Delivered Test 2 > Flashcards

Ch. 3 How a Breath is Delivered Test 2 Flashcards

1
Q

The phases of a breath and the variable that controls each portion of the breath is called a

A

phase variable

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2
Q

The _________ variable begins with inspiration

A

trigger

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3
Q

This limits the value of pressure, volume, flow, or time during inspiration

A

limit variable

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4
Q

The limit variable does not

A

end inspiration

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5
Q

This ends inspiration

A

cycle variable

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6
Q

The baseline pressure establishes the….

A

baseline during exhalation before inspiration is triggered

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7
Q

What is usually identified as the baseline variable

A

Pressure

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8
Q

The mechanism the vent uses to begin inspiration is the

A

triggering mechanism (trigger variable)

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9
Q

When the vent can initiate a breath after a set time, that is referred to as

A

time triggering

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10
Q

When the pt can initiate a breath based on pressure, flow, or volume, is referred to as

A

pt triggering

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11
Q

What are the most common triggering variables (2)

A

pressure and flow

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12
Q

___________ triggering and _______ triggering from the diaphragm output can also be used

A

volume and neural

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13
Q

The vent delivers a mandatory breath by beginning inspiration after a set time has elapsed

A

time triggering

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14
Q

The number of mandatory breaths delivered by the vent is based on the

A

length of TCT
(Ex: If the vent is set a 10bpm, every 6 seconds the vent will trigger a breath)

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15
Q

When the vent detects changes in pressure, flow,or volume what breath occurs?

A

a pt-triggered breath

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16
Q

___________ and ______ are common pt-triggered mechanism

A

Pressure and flow

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17
Q

How can the RT pt enable pt triggering?

A

The RT must specify the sensitivity setting called pt effort (pt-triggering) control

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18
Q

Sensitivity can either be _________ or ______

A

pressure or flow

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19
Q

The less pressure or flow change require to trigger a breath

A

the more sensitive the machine is to the pt’s effort

(Ex: The vent is more sensitive to the pt effort at a setting of 0.5 cm H20 than a setting of -1 cm H20)

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20
Q

The sensitivity level for pressure triggering is usually set at about

A

-1 cm H20

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21
Q

If the sensitivity level is set incorrectly the vent may not be

A

sensitive enough to the pt’s effort and the pt will need to work too hard to trigger the breath

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22
Q

If the vent is too sensitive, it can cause

A

auto-trigger
(the machine triggers a breath w/o the pt making an effort)

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23
Q

This occurs when the vent detects a drop in flow in the pt circuit during exhalation

A

Flow triggering

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24
Q

Flow triggering has been shown to require less WOB than

A

pressure triggering

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25
Q

Occurs when the vent detects a small drop in volume in the pt circuit during exhalation

A

Volume triggering
(the machine interprets the decrease in volume as a pt effort and begins inspiration)

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26
Q

______________ is timed from the beginning of inspiratory flow to the beginning of ____________.

A

Inspiration;
expiratory

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27
Q

A limit variable is the..

A

maximum valve that a variable (pressure, volume, flow, or time) can attain

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28
Q

Reaching the set limit variable,

A

DOES NOT END INSPIRATION

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29
Q

Example of limit variable:
A ventilator is set to deliver a maximum pressure of 25 cm H20 and the inspiratory time is set to 2 seconds. The maximum pressure that can be attained during inspiration is 25 cm H20, BUT inspiration will end only after 2 seconds have passed.
- Such breath is described as a pressure-limited, time-cycled breath

A

Something to know

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30
Q

What are some types of variables (3)

A
  • pressure
  • volume
  • flow
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31
Q

This allows pressure to rise to a certain value but not exceed it

A

Pressure limited

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32
Q

To prevent excessive pressure from entering the pt’s lungs, what is set?

A

A high-pressure limit control

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33
Q

When the vent reaches the high-pressure limit control…

A

excess pressure is vented through a spring-loaded pressure release pop-off valve

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34
Q

This is controlled by an electronically operated valve that measures the flow passing through the vent circuit during a specific interval

A

volume limited

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35
Q

If gas flow from the vent to the pt reaches but does not exceed a maximum value before the end of inspiration, the vent is

A

flow limited
(only a certain amount of flow can be provided)

36
Q

The variable that the vent uses to end inspiration is called the

A

cycling mechanism

37
Q

Only one of four variables can be used at any given time by the vent to end inspiration. What are they?

A
  • volume
  • time
  • flow
  • pressure
38
Q

When a breath is terminated when the Vt has been delivered

A

Volume cycled

39
Q

Example of volume cycled:

If I have a pt set to get 500mL of Vt, once that 500mL has been given, the breath will end and the pt will cycle into expiration

A

Something to know

40
Q

In most cases this remains constant even if the pt’s lung characteristics change

A

volume

41
Q

The __________ required to deliver the set volume and gas flow will vary as the pt’s respiratory system compliance and Raw changes

A

pressure

42
Q

The volume of gas that leaves the vent outlet is not the volume that enters the pt’s lungs

A

Tubing compressibility

43
Q

During inspiration, positive pressure builds up in the pt circuit resulting in..

A

expansion of the pt circuit and compression of some gas in the circuit. The compressed gas never reaches the pt’s lungs (Boyle’s)

44
Q

For every 1 cm, how much gas is lost to tubing compressibility? (range)

A

1 to 3mL

45
Q

Example of time cycled

If I set the vent at 10bpm, every 6 seconds the time will cycle the breath into expiration.

A

This is based on TCT

46
Q

The interval is controlled by a timing mechanism in the vent, which is not affected by the pt’s

A

respiratory system compliance or airway resistance

47
Q

With this, an increase in airway resistance or a decrease in compliance does not affect the flow pattern or volume delivery as long as the working pressures of the vent are adequate

A

time-cycled, volume control ventilation

47
Q

A breath is considered ______ ___________ if the inspiratory phase ends when a predetermined time has elapsed

A

time cycled

48
Q

With this both volume and flow vary

A

time-cycled, pressure control

49
Q

Time-cycled, pressure controlled is commonly called

A

pressure-controlled ventilation

50
Q

Why is pressure-controlled ventilation used?

A

The inspiratory pressure can be limited, which protects from lung injuries caused by high pressures, however the variability of the Vt delivery can be a concern

51
Q

With flow-cycled ventilation, the vent

A

cycles into the expiratory phase once the flow has decreased to a predetermined value during inspiration

52
Q

With flow-cycled what 3 things can vary based on changes in lung CharacterIstics

A
  • volume
  • pressure
  • time
53
Q

Flow cycling is the most common cycling mechanism used in

A

pressure support mode

54
Q

In pressure cycled ventilation, inspiration ends when a

A

set pressure threshold is reached at the mouth or upper airway

55
Q

During pressure-cycled ventilation, the volume delivered to the pt depends on the… (4)

A
  • flow delivered
  • the duration of inspiration
  • the pt’s lungs characeteristics
  • the set pressure
56
Q

What is an advantage of pressure cycle vents?

A

They limit peak airway pressures (avoids barotrauma)

57
Q

What is a disadvantage of pressure-cycled vents?

A

Anytime lung characteristics change, the pt may not receive the Vt that is intended

58
Q

Pressure cycling occurs in…

A

volume-controlled breaths when the pressure exceeds the maximum safety high-pressure limit

59
Q

This is designed to maintain air in the lungs at th end of inspiration before the exhalation valve opens

A

Inflation hold (Inspiratory pause)

60
Q

During an inflation hold, the

A

inspired volume remains in the pt’s lung and the expiratory valve remains closed for a brief period or pause time

61
Q

Inflation hold is done to?

A

To get the plateau pressure (Pplat)

62
Q

What calculation is the Pplat used in?

A

static compliance

63
Q

What is the purpose of doing an inflation hold?

A

It used to increase peripheral distribution of gas and improve oxygenation

64
Q

The expiratory phase encompasses the period from the

A

end of inspiration to the beginning of the next breath

65
Q

The main concern during expiration is

A

Does the pt have enough time to exhale to baseline

66
Q

During MV, expiration begins when inspiration

A

ends, the expiratory valve opens, and the expiratory flow begins

67
Q

What can occur if the expiratory time is to short

A

Air-trapping

68
Q

If an adequate amount of time is not provided for exhalation, air-trapping and hyperinflation can occur leading to a phenomenon called

A

auto-PEEP or intrinsic PEEP

69
Q

The baseline variable is the parameter that generally is

A

controlled during exhalation

70
Q

Baseline pressure can be…..
Or it can be

A

zero (atmospheric) zero end-expiratory pressure (ZEEP);
positive if the baseline pressure is above zero, positive end-expiratory pressure (PEEP)

71
Q

REMEMBER Baseline pressure is PEEP in the Dynamic and static equation

A

something to know

72
Q

____________ is the most common baseline

A

Pressure

73
Q

______________ _______ or end-expiratory pause is a maneuver transiently performed at the end of expiration

A

Expiratory hold

74
Q

What is the purpose of the expiratory hold?

A

To measure pressure associated w/ air trapped in the lungs at the end of expiration (auto-PEEP)

75
Q

Can you do this measurement on a spontaneous breathing pt?

A

No

76
Q

How can pts accomplish a prolonged expiration?

A

Pursed-lip breathing

77
Q

What is the purpose of pursed-lip breathing

A

To create back pressure so that the alveoli do not collapse on expiration

78
Q

How do vents mimic pursed-lip breathing?

A

Expiratory retard, which added a degree of resistance to exhalation

79
Q

Expiratory retard should prevent

A

early airway closure and improve ventilation

80
Q

What are 2 methods of applying continuous pressure to the airways which have developed to improve oxygenation in pt’s w/ refractory hypoxemia?

A
  • CPAP
  • PEEP
81
Q

CPAP involves the application of

A

pressure above ambient pressure throughout inspiration and expiration to improve oxygenation in a spontaneous breathing pt

82
Q

PEEP involves applying

A

positive pressure to the airway throughout the respiratory cycle

83
Q

_______ becomes the baseline pressure during MV

A

PEEP

84
Q

CPAP and PEEP help prevent early airway closure and alveolar collapse at the end of expiration by

A

increasing (and normalizing) the pt’s FRC, which in turn allows for better oxygenation

85
Q

PEEP is defined as

A

positive pressure at the end of exhalation during spontaneous breathing or MV

Topics of Respiratory Care (20 decks)

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