Mechanical Ventilation Flashcards
(71 cards)
1
Q
The two main factors that influence ventilation are
A
Respiratory rate, tidal volume
2
Q
Lung compliance refers to
A
How distensible the lungs are
3
Q
When lung compliance is decreased, work of breathing is
A
Increased
4
Q
When functional residual capacity is decreased, there is
A
Less air in the lungs at the end of expiration
5
Q
When PaC02 rises, chemoreceptors cause
A
An increase in ventilation
6
Q
Diffusion of oxygen and carbon dioxide is influenced by the
A
Thickness of the alveolar capillary interface
7
Q
Carbon dioxide levels are primarily determined by
A
Respiratory rate or tidal volume (ventilation)
8
Q
Tidal volume is
A
The volume of air in one breath during normal relaxed breathing
9
Q
During inspiration
A
Intrathoracic and interpulmonary pressures decrease
The diaphragm contracts
Intercostal muscles contract & thoracic cavity increases in size
10
Q
In the upright person, the lower portions of the lung receive
A
More ventilation than the upper portions
11
Q
In the upright person, the lower portions of the lung receive
A
More blood flow/perfusion than the upper portions
12
Q
The right lung has
A
2 fissures and 3 lobes
13
Q
Type 1 alveolar cells
A
Comprise 90% of the alveolar wall
Are the main structural cells of the alveolar wall
Are susceptible to injury
14
Q
Exchange of respiratory gases does not occur in
A
Terminal bronchioles
15
Q
Exchange of respiratory gases occurs in all of the following
A
Alveolar ducts
Alveoli
Respiratory bronchioles
16
Q
DECREASES airway resistance
A
SNS stimulation
17
Q
The most sensitive region in the respiratory tract for triggering the cough reflex is
A
Carina
18
Q
Oxygen levels in the arterial blood are influenced by
A
Ventilation
Perfusion
Diffusion
19
Q
Pulmonary surfactant:
A
Prevents alveolar collapse
Reduces alveolar surface tension
Increases lung compliance
Is secreted by Type II cells
20
Q
Ventilation-perfusion mismatching affects which of the following primarily
A
Work of breathing
21
Q
Ventilation
A
the movement of gases in and out of the lungs
22
Q
Gas exchange
A
refers to the exchange of oxygen and carbon
dioxide across the alveolar-capillary level.
23
Q
Normal ventilation
A
Muscular contraction causes the ribs to move outward and the diaphragm to move downward, resulting in an increase in the volume of the thoracic cage.
This increased volume / size results in a increased negative intrathoracic pressure (and intra-pulmonary pressure) - which, in turn, ‘sucks‘ the air into the lungs - and inhalation or inspiration occurs. It is key to note that inhalation is active - it requires muscular work for it to occur.
Exhalation or expiration of air is passive. The ventilatory
muscles relax and the diaphragm moves up. The simple
process of muscular relaxation results in the thoracic cage volume decreasing, as well as increased intrathoracic and intrapulmonary pressures - and air moves out of the lungs.
24
Q
Physiologic effects of mechanical ventilation on hemodynamic
function
A
As intrathoracic pressure falls, the resistance for blood flow returning to the right side of the heart is less. Thus, the mechanics of normal breathing support venous return, adequate preload and cardiac output.
The increased intrathoracic pressure that occurs during inspiration for a mechanically ventilated patient can
make it more difficult for the blood to return to the heart,
inhibiting venous return and lowering the patient’s preload.
At the same time, the increased intrathoracic pressure can falsely increase a patient’s CVP value. the patient’s actual preload might have dropped too low to maintain adequate cardiac output and as a result, the patient becomes hypotensive. I
25
A/C
Assist control mode, respiratory rate and tidal volume are set on the ventilator. Patients can
initiate additional breaths above the set rate (commonly referred to as “assisting” or “triggering” the ventilator). When a patient assists above the set rate, they receive the set tidal volume. Other settings on A/C include PEEP and Fi02.
26
Absorption Atelectasis
When a patient is on high levels of oxygen 90-100% the oxygen washes out the nitrogen.
As the oxygen in the alveoli is absorbed into the blood stream, the alveoli collapse.
Nitrogen is important in supporting alveoli opening and is not absorbed into the blood
stream when at normal atmospheric pressures.
27
Acute respiratory failure
Acute respiratory failure is the primary indication for initiation of mechanical ventilation
(Clochesy et al., 1996). Acute respiratory failure can be broadly categorized into two types:
ventilatory failure or an issue related to ventilatory mechanics, and hypoxemic failure or
inadequate gas exchange across the alveolar-capillary membrane.
28
Alveolar hypoventilation
Occurs when the amount of oxygen brought into the alveoli does not meet the needs of the
body (Urden, Stacy and Lough, 2022). Common conditions that can cause alveolar
hypoventilation include narcotic overdoses or airway obstruction.
29
APA
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30
Artificial airway
A mechanical device used for securing unobstructed respiration during general anesthesia
or other occasions in which the patient is not ventilating or exchanging gases properly.
Includes an endotracheal tube and a tracheostomy tube
31
Assist/control
Assist control mode, respiratory rate and tidal volume are set on the ventilator. Patients can initiate additional breaths above the set rate (commonly referred to as “assisting” or “triggering” the ventilator). When a patient assists above the set rate, they receive the set
tidal volume. Other settings on A/C include PEEP and Fi02.
32
BiPAP
This type of ventilation is similar to Pressure Support with PEEP. Bipap uses a combination
of inspiration support called iPAP and expiration positive pressure called EPAP. In the
spontaneously breathing patient, BiPAP is an effective method of improving ventilation and
gas exchange (Urden, Stacy and Lough, 2022)
33
CPAP
CPAP is used in spontaneous modes of ventilation (i.e. pressure support). It is designed to
splint the airway open as in sleep apnea or to maintain the alveoli open to support gas
exchange. It is similar to positive end expiratory pressure or PEEP. In the critical care areas
CPAP is manipulated to improve gas exchange and Pa02.
CPAP machines are used in the treatment of sleep apnea.
34
Endotracheal (ETT) tube
A plastic tube device designed to prevent the tongue from obstructing the airway yet allow
for the passage of gases into the lungs (Urden, Stacy and Lough, 2022). Comes in sizes for
neonate to adult. Most common sizes in adult critical care are 7.0-8.5 Fr. The process of
inserting an ETT is referred to as ‘intubation’.
35
Flow
Flow at its simplest is essentially the measure of a volume over a period of time. A mechanical ventilator must produce a pressure which delivers a volume of air to a patient. This pressure over time is the flow of air to the patient. This setting is either adjusted by the
RT or is set by the mechanical ventilator computer.
36
Flow-cycled ventilation
Flow cycled ventilation is the most common method of determining the start of expiration in
pressure support ventilation.
The mechanical ventilator monitors the pressure and volume or flow that is entering the
lungs. When the flow begins to slow the mechanical ventilator switches from the inspiration
phase to the expiration phase.
37
Gas exchange
The exchange of oxygen and carbon dioxide at the alveolar-capillary level and at the
capillary-cellular level. Sometimes referred to as ‘respiration.’
38
Hypoxemic failure
Is a common type of respiratory failure. It is a the result of impaired gas exchange. The
impaired gas exchange can be the result of alveolar hypoventilation or from V/Q
mismatches.
39
Iron lungs
```
A negative pressure type
of ventilation used in the
1950’s. The patient’s body
(with the exception of the
head) would be inside the
tube. The pressure inside
the tube would be
decreased, forcing the
chest to rise and air would
be entrained through the
normal respiratory
passages. For exhalation
the pressure in the tube would be increased forcing the chest to collapse slightly and air
would be exhaled by the patient.
```
40
Mechanical ventilation
Provides support of or assistance with breathing for patients who are unable to maintain
adequate ventilation to supply his or her body tissues with oxygen. There are numerous
settings that assist with ventilation and gas exchange.
41
Mode of ventilation
Refers to the way that air/oxygen is delivered to the patient during mechanical ventilation.
The selection of a particular mode of ventilation determines the extent to which patients
participate in their own ventilatory pattern. A variety of modes are available, and some
modes can be used in conjunction with each other. The choice of mode depends on the
patient’s condition and comfort, the goals of treatment, and the availability of the mode on
the ventilator.
42
Oxygen toxicity
Occurs in patients receiving oxygen therapy at greater than 50% for longer than a 24 hour
period. The high level of oxygen stimulates release of oxygen free radicals which potentiate
inflammation in the lungs and can lead to further damage to the lungs. In clinical practice
PEEP is used to decrease the amount of oxygen used.
43
PCV
This is a type of controlled mode ventilation where a set pressure is delivered to the patient.
The pressure is limited, thus preventing barotrauma. Tidal volume will fluctuate depending
on lung compliance. A set respiratory rate is used as well. If the patient assists above the
set rate, they receive the set pressure. Nurses must monitor tidal volume, minute volume,
and PaC02 as indicators of effectiveness of gas exchange.
44
PEEP
This is a pressure exerted at the end of expiration. It is used to hold open the alveoli to
assist with gas exchange. Manipulation of this setting improves Pa02. It is commonly set
between 5-20cm H20.
45
Positive end expiratory pressure
This is a pressure exerted at the end of expiration. It is used to hold open the alveoli to
assist with gas exchange. Manipulation of this setting improves Pa02. It is commonly set
between 5-20cm H20.
46
Pressure
Is the force required to deliver a flow or a volume of gas to a patient. Pressure is monitored
in a number of ways in mechanical ventilation. The peak pressure is monitored to ensure
that the pressure used to deliver a flow or volume does not damage the lungs. Pressure is
used as a setting to minimize barotrauma to the lungs.
47
Pressure control ventilation
This is a type of controlled mode ventilation where a set pressure is delivered to the patient.
The pressure is limited, thus preventing barotrauma. Tidal volume will fluctuate depending
on lung compliance. A set respiratory rate is used as well. If the patient assists above the
set rate, they receive the set pressure. Nurses must monitor tidal volume, minute volume,
and PaC02 as indicators of effectiveness of gas exchange.
48
Pressure support ventilation
Is a spontaneous mode of mechanical ventilation similar to Bipap. When the patient triggers
the inspiration cycle of the mechanical ventilator, a set pressure is delivered that augments
the patient’s own inspiratory efforts. It improves ventilation and decreases work of
breathing in spontaneously breathing patients. It is sometimes used as a weaning mode.
49
Pressure-cycled ventilation
In this mode of ventilation, the ventilator delivers a set pressure once that threshold is
reached, expiration valve opens allowing patient to exhale. The volume delivered to patient
depends on flow, how long the inspiration time is and lung compliance.
50
PSV
Is a spontaneous mode of mechanical ventilation similar to Bipap. When the patient triggers
the inspiration cycle of the mechanical ventilator, a set pressure is delivered that augments
the patient’s own inspiratory efforts. It improves ventilation and decreases work of
breathing in spontaneously breathing patients. It is sometimes used as a weaning mode.
51
Sensitivity
This is a parameter most often preset by the ventilator software or the RT. It is how
sensitive the ventilator is to the patient’s own breathing efforts. It is commonly set at -2cm
H20. This means that the patient has to generate a negative 2 cm H20 pressure, which is a
very small amount of pressure.
52
SIMV
Is a combination mode of assist control and spontaneous breathing. The ventilator delivers
a set rate and tidal volume. If the patient breathes above the set rate, they generate their
own tidal volume. The spontaneous efforts are synchronized to the set rate. This means
that if the patient decides to take a spontaneous breath and it is time for a set breath the
ventilator with work with the patient to deliver the set tidal volume. This synchronization
improves comfort. Pressure support can be added to the settings and will affect the
spontaneous breaths.
53
Suctioning
This is the process of clearing out secretions from an airway using a sterile, inline suction
suction catheter that comes as an attachment for the ET tube. It is a common nursing
procedure in critical care and is one of the interventions to implement when a patient’s
saturation decreases or the high pressure alarm or low tidal volume alarm sounds.
54
Synchronized intermittent mandatory ventilation
Is a combination mode of assist control and spontaneous breathing. The ventilator delivers
a set rate and tidal volume. If the patient breathes above the set rate, they generate their
own tidal volume. The spontaneous efforts are synchronized to the set rate. This means
that if the patient decides to take a spontaneous breath and it is time for a set breath the
ventilator with work with the patient to deliver the set tidal volume. This synchronization
improves comfort. Pressure support can be added to the settings and will affect the
spontaneous breaths.
55
T-piece
Is used in spontaneously breathing patients that require an artificial airway. It is a high flow
oxygen tubing attached either to a tracheotomy tube or an OETT. Nurses must monitor the
patient carefully as there is no way to display tidal volume or respiratory rates. Can be used
as a weaning mode.
56
Time cycled ventilation
In this mode of ventilation, a set time for inspiration is used. Since the time is set for
inspiration along with a rate and volume, the only parameter that varies is pressure.
Changes in compliance do not impact volume as the machine adjusts flow to compensate.
There are types of ventilators that use this mode in practice. It is above the scope of the
course to discuss this mode further.
57
Ventilation
In terms of mechanical ventilators, ventilation refers to the movement of gases in and out of
the lungs.
This movement is measured as tidal volume, minute volume.
58
Ventilatory failure
Is a type of acute respiratory failure. It is the failure to move gases adequately in and out of
the lungs.
Common causes can be exacerbation of asthma, airway obstruction, or respiratory muscle
weakness.
59
Volume
Is amount of gas delivered to the patient. Depends of pressure and time. It is a commonly
monitored parameter that includes tidal volume or minute volume.
60
Volume-cycled ventilation
Similar to assist control. The inspiratory phase ends when the set volume is delivered.
61
Weaning
The process of moving from a controlled mode of ventilation to a spontaneous mode and
decreasing the support required to the point that the patient is ready to be removed from
mechanical ventilation.
62
TO increase Oxygention we.... (vent settings)
Increasse Fi02 or PEEP
63
TO increase Ventilation we.... (vent settings)
Increase Vt or RR
64
causes of ventilatory Failure
✦Neuromuscular diseases (e.g., Guillain‑Barré syndrome,
myaesthenia gravis)
✦Spinal cord injury
✦Musculoskeletal abnormalities (e.g., chest wall trauma)
✦Suppression of CNS respiratory function (e.g., drug poisoning)
✦general anesthesia
✦post cardiorespiratory arrest
✦brain injury
✦upper airway obstruction
65
causes of Oxygenation Failure
```
✦Infectious diseases of the lung (e.g., pneumonia, TB)
✦Aspiration pneumonia/pneumonitis
✦Pulmonary edema
✦Atelectasis
✦Pulmonary fibrosis
```
66
Describe the arterial blood gas changes you would anticipate in a patient experiencing (Type I) respiratory failure
ABG changes consistent with Hypoxemic failure include
decreased PaO2. The pH will depend on the degree of
hypoxemia and the length of time the patient has been
hypoxemic.
when PaO2 falls below 60 mmHg, the peripheral chemoreceptors will sense this and increase the rate and depth of ventilation will result more CO2 being exhaled, resulting in a lower than normal CO2 and a respiratory alkalosis. (Lox PCOS and alkaltoic PH)
later stages of hypoxemic failure, the ABGs will show
changes consistent with both hypoxemic and ventilatory failure (acidotic pH, elevated PCO2, decreased PO2)
67
Describe the arterial blood gas changes you would anticipate in a patient experiencing ventilatory (Type II) respiratory failure
elevated PaCO2 and decreased (acidotic) pH.
68
Cuff pressures should be maintained at
20-25 mm Hg pressure
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Purpose of Succinycholine:
Succinycholine is a depolarizing
neuromuscular blocking agent (Morton & Fontaine, 2013). Most commonly used to facilitate intubation, it causes muscle paralysis and apnea.
it has rapid onset (1–2 minutes), is short acting (lasts about 6–10 minutes), and is excreted via the kidneys. Typically, succinylcholine causes
fasciculations
A common side effect is the shift of potassium from inside to outside the cell, leading to high potassium levels and the potential for cardiac dysrhythmias.
70
Best method for confirming ETT position:
End Tidal CO2
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peep setting
5-15
