Mechanical Ventilation Flashcards

1
Q

Oxygen delivery equation

A

DO2= cardiac output x arterial O2 Content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Reasons for oxygen delivery failure

A

hypotension, acidosis, coagulopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

oxygen use equation

A

VO2=Cardiac output x O2a-O2v

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The normal oxygen extraction ratio is

A

about 25%

heart has very high demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The anesthesia goal of oxygen therapy is

A

to maintain oxygenation and ventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The oxygen therapy goal is

A

prevention and correction of hypoxemia and tissue hypoxia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Surgical patients have an

A

increased risk of hypoxemia & hypoxia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Hypoxemia is

A

deficiency of O2 in blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Hypoxia is

A

O2 delivery to tissues not sufficient to meet metabolic demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Types of hypoxia include

A

hypoxic, circulatory, hemic, demand, and histotoxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Hypoxia signs and symptoms include

A

vasodilation, tachycardia, tachypnea, cyanosis, confusion, and lactic acidosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Improving oxygenation in mechanically ventilated patients includes

A

treatment tailored to cause
utilizing increase VE, increased cardiac output, increased O2 carrying capacity, optimize V/Q relationship, decrease O2 consumption, increase FiO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The nasal cannula (flow rates)

A

flow rates 1-6 L/min

FiO2 increases about 4% per L/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Simple face masks (FiO2)

A

minimum 6L flow required to prevent rebreathing

FiO2 40-60%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Face masks with reservoirs

A

FiO2 60-100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Venturi masks

A

have more precise FiO2 of 24-50%
have to set flow rate
Based off of Bernoulli’s theory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Oxygen toxicity occurs from

A

high FiO2 over long periods which can be harmful to lung tissue and cause
decreased ciliary movement, alveolar epithelial damage, and interstitial fibrosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Oxygen toxicity is dependent upon

A

FiO2, duration, patient susceptibility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Safe levels of oxygen to prevent oxygen toxicity is

A

100% O2 for up to 10-20 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Oxygen toxicity occurs from

A

50-60% O2 for more than 24-72 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Absorption atelectasis occurs when

A

nitrogen is replaced by oxygen
under-ventilated alveoli have decreased volume- due to greater uptake of oxygen
increases pulmonary shunting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Induced hypoventilation occurs due to

A

Chronic CO2 retainers rely on hypoxic drive
peripheral chemoreceptors are triggered by hypoxemia
Increased O2 can lead to hypoventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Fire hazards can occur because

A

O2 supports combustion

use extreme caution with head and neck cases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Retinopathy occurs

A

with O2 therapy in neonates; it can lead to vascular proliferation, fibrosis, retinal detachment, and blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Populations at risk of retinopathy include

A

<36 weeks gestational age
weight <1500 gm
up to 44 weeks gestational age are considered high risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Safe O2 administration to prevent retinopathy is

A

PaO2 60-80 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Hypercapnia is

A

increased CO2 >45 mmHg

increased CO2 concentration or increased CO2 production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Hypercapnia is caused by

A

increased alveolar dead space- decreased alveolar perfusion, interruptions in pulmonary circulation, pulmonary disease

Decreased alveolar ventilation- can be central or peripheral defect, respiratory depression most common cause in immediate postoperative period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Clinical manifestations of hypercapnia include

A

directly produces vasodilation of peripheral vessels, indirectly increases HR after catecholamine release, produces effects due to an acidotic state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Non-specific signs of hypercapnia include

A

headache, nausea/vomiting, sweating, flushing, shivering, restlessness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Treatment for hypercapnia includes:

A

adjust treatment to the cause

increase minute ventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Considerations for hypercapnia (CNS, CV, and pulm)

A

CNS considerations: regulation of ventilatory drive, cerebral blood flow
cardiovascular considerations: depression of smooth muscle and cardiac muscle, increased catecholamine release, vasodilation versus vasoconstriction
Pulmonary considerations: increased respiratory rate, increased pulmonary vascular resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Hypocapnia is

A

CO2 <35 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Hypocapnia typically caused by

A

iatrogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Hypocapnia clinical manifestations include

A

CNS: decrease CBF
CV: decrease in CO, coronary constriction
Pulmonary: hypoxemia may result from hypoventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Treatment of hypocapnia includes

A

decreasing minute ventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Goals of mechanical ventilation is

A

to maintain homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Goals of mechanical ventilation in the OR is to

A

ensure adequate oxygenation and CO2 removal for safe and effective surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Goals of mechanical ventilation in the ICU is to

A

treat severe respiratory distress, provoke lungs with a “break” to rest and heal, decreases O2 consumption by providing rest for respiratory muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Peak inspiratory pressure (PiP) is

A

total pressure required to distend LUNGS and AIRWAYS

Pressure used to calculate DYNAMIC COMPLIANCE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Plateau pressure is

A

distending pressure to expand ONLY THE LUNGS
measures redistribution of air flow through lungs
plateau pressure is used to calculate STATIC COMPLIANCE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

The variables we control include (control variables)

A

respiratory rate, tidal volume, pressure (PiP, Plat/ PAW)

I:E ratio (I:E)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Depending on the mode of ventilation selected you can control

A

either tidal volume or pressure delivered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

In the total respiratory cycle, each breath has 4 parts:

A
  1. start of inspiration
  2. inspiration itself
  3. end of inspiration
  4. expiration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

The trigger variable is

A

the start of inspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

The limit variable is

A

maintenance of inspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

The cycling variable is

A

transition to expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

The baseline variable is

A

end expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

The trigger variable represents

A

the start of inspiration

can be affected with or without patient inspiratory effort by either pressure, volume, flow, or time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Pressure as the trigger variable:

A

pressure decrease in circuit stimulates ventilator to deliver breath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Volume as the trigger variable:

A

volume change in circuit can stimulate ventilator to deliver breath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Flow as the trigger variable:

A

change of flow in circuit stimulates ventilator to deliver breath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Time as the trigger variable:

A

set time interval triggers ventilator to deliver breath

*** this occurs independent of patient effort

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

The limit variable

A

controls how an inspiratory breath is maintained, once threshold is reached variable will not exceed set limit
-this DOES NOT cause termination of inspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

When pressure is set as the limit variable:

A

sets upper pressure limit that cannot be exceeded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

When volume is set as limit variable:

A

sets upper volume limit that cannot be exceeded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

When flow is set as the limit variable:

A

sets maximum airflow that cannot be exceeded

58
Q

The cycling variable is the

A

transition from inspiration to expiration

based on either volume, pressure, flow, or time

59
Q

With volume set as the cycling variable:

A

ventilator delivers flow until set volume achieved

if inspiratory pause set (typically 10-20%) this variable changes to time-based cycling variable

60
Q

With pressure set as the cycling variable:

A

once pressure achieved flow will transition to expiration

61
Q

With flow set as the cycling variable:

A

once inspiratory flow drops below set threshold (default at 25%) ventilator will transition to expiration
-noted in pressure support ventilation mode

62
Q

With time set as the cycling variable:

A

ventilator terminates inspiratory breath after predetermined inspiratory time has been delivered

63
Q

The baseline variable is

A

the pressure maintained in the circuit at end expiration (PEEP), must be individualized to patient, used to prevent atelectasis

64
Q

PEEP is

A

the alveolar pressure above atmospheric

goal: used to improve oxygenation

65
Q

Intrinsic PEEP is

A

secondary to incomplete expiration

–referred to as auto-PEEP

66
Q

Extrinsic PEEP is:

A

provided by a mechanical ventilator

-referred to as applied PEEP

67
Q

Auto PEEP is

A

incomplete expiration prior to initiation of next breath

causes progressive air trapping

68
Q

Causes of PEEP include

A

high minute ventilation
expiratory flow limitation
expiratory resistance

69
Q

Volume control ventilation:

A
delivers set tidal volume at set respiratory rate
-TIME is the set trigger variable
-VOLUME is the limit variable
-TIME is cycling variable 
airflow will remain constant
70
Q

With volume control ventilation, airway pressure will

A

change on a breath-by-breath basis during this mode of ventilation based on changing respiratory compliance

71
Q

Reasons for choosing VCV include:

A

maintenance of set minute ventilation through direct manipulation of Vt and RR

  • must set individualized alarms for airway pressure to protect patient
  • increasing airway or lung resistance will stimulate generation of higher pressure to deliver set Vt
72
Q

Pressure control ventilation:

A

delivers set inspiratory pressure at set respiratory rate
TIME is the trigger variable
PRESSURE is the limit variable
TIME is the cycle variable

73
Q

With pressure control ventilation, airway pressures are controlled by

A

the user, Vt can change on a breath-by-breath basis depending on total respiratory system compliance

74
Q

PCV should be chosen to

A

set pressure limit to avoid barotrauma from delivery of excessive pressure

  • decelerating flow pattern allows for homogenous distribution of inspired gas throughout lungs- theoretically improves ventilation pattern and decreases work of breathing
  • must set patient appropriate high and low Vt alarms as change in respiratory compliance can affect Vt delivered
75
Q

Pressure control volume guarantee is

A

when respiratory cycle variables mirror PCV, however ventilator adjust pressure delivered if current volume is not at set volume

  • adjustments take 3-5 breaths to complete
  • can allow for atelectasis development if compliance decreases and ventilator is delayed in providing adequate pressure to distend lungs
76
Q

Synchronized intermittent mandatory ventilation (SIMV)

A

delivers set Vt at a set respiratory rate in conjunction with patient initiated breaths
TIME or PATIENT stimulate the trigger variable
FLOW is the limit variable
VOLUME is the cycle variable
-patient initiated breaths are not supported (unless in SIMV-PSV)

77
Q

Reasons for choosing SIMV

A

useful when weaning from controlled mechanical ventilation to spontaneous respiration- less desynchrony with patient initiated breaths

78
Q

With SIMV, hypoventilation can occur

A

if set Vt and RR are too low and the patient’s spontaneous respiration effort is inadequate

79
Q

With SIMV, hyperventilation can occur if

A

using SIMV-PSV and pressure support level too high

80
Q

Pressure support ventilation is

A
supported mode of ventilation for spontaneously breathing patient
Pressure support level set by user:
PATIENT is the trigger variable
PRESSURE is the limit variable
FLOW is the cycle variable
81
Q

With pressure support ventilation, patient controls most aspects of venilation

A

but the anesthetics can adjust certain variables to augment or limit support given to prepare patient for extubation

82
Q

Reasons to choose pressure support ventilation:

A

great for end of case in preparation for extubation- patient must be breathing spontaneously or ventilator will switch to backup mode
Just like PCV pressure is controlled, changes in respiratory system compliance will alter Vt delivered

83
Q

Physiologic respiration occurs through

A

negative pressure

84
Q

Negative intrapleural pressure provides

A

a positive trans-pulmonary pressure to minimize atelectasis at baseline
Ptp= Palv-Ppl

85
Q

Anesthetic and surgical factors alter

A

chest wall muscle tone which alters the intrapleural pressure gradient

86
Q

Maintaining a positive transpulmonary pressure during surgery is dependent on

A

maintaining alveolar pressure

87
Q

Anesthesia and surgical effects on lungs include

A

loss of muscle tone & elevated intraabdominal pressure

88
Q

Elevated intraabdominal pressure can occur from

A

increased BMI, Pneumoperitoneum, trendelenburg position

89
Q

Loss of muscle tone can occur from

A

upper airway muscle obstruction

chest wall and diaphragm- abdominal contents cephalad displacement or alveolar compression

90
Q

Induction of anesthesia causes a

A

reduction in FRC

91
Q

Transition from upright to supine position

A

decreases FRC by 0.8-1L

92
Q

Induction agents further reduce FRC by

A

0.4-0.5 L

93
Q

Total reduction is

A

1.2-1.5L, bringing lung volume close to residual volume

94
Q

Non-recruitable lung tissue can result from

A

ARDS- cellular debris, edema

95
Q

Recruitable lung tissue can result from

A

general anesthesia- loss of FRC, atelectasis

96
Q

Factors that contribute to alveolar collapse include

A

position, induction, FiO2, maintenance, and emergence

97
Q

Emergence can cause alveolar collapse because

A

high FiO2 promotes postoperative atelectasis

absence of CPAP–> continued lung collapse

98
Q

Maintenance can cause alveolar collapse because

A

progressive airway closure with decreasing compliance

99
Q

FiO2 can cause alveolar collapse because

A

resorption behind closed airways–> atelectasis

increased FiO2–> faster resorption

100
Q

Induction can cause alveolar collapse because

A

loss of muscle tone–> decreased FRC

101
Q

Position can cause alveolar collapse because

A

increased closing pressure–>decreased FRC

102
Q

Ventilator induced lung injury can occur from

A

mechanical ventilation
ventilation induced lung injury
ventilation associated lung injury

103
Q

Mechanical ventilation can induce lung injury

A

leading to potentially irreversible structural and functional damage

104
Q

Ventilation induce lung injury is when

A

ventilator does not cause injury but the settings of the ventilator do

105
Q

Ventilation associated lung injury is

A

specific to the OR setting

106
Q

Ventilation associated lung injury can be caused by

A

volutrauma, barotrauma, atelectrauma, or biotrauma

107
Q

Biotrauma is

A

damage from release of inflammatory mediators

108
Q

Atelectrauma is

A

damage from repeated collapse and re-inflation

109
Q

Barotrauma is

A

damage from positive pressure effects

110
Q

Volutrauma is

A

damaged endothelium, decreased surfactant, and increased capillary leak

111
Q

Conventional lung ventilation is

A
strategy that promotes VALI, not individualized
Vt: 10-15 mL/kg TBW
PEEP: 0-5 cmH2O
I:E: no greater than 1:2
FiO2: provider preference
112
Q

Lung protective ventilation is

A

a strategy that protects against VALI
individualized to patient and surgery
adjust settings based on patient monitors and ventilator data

113
Q

Lung protective ventilation initial maintenance settings include:

A
low Vt: 6-8 mL/kg IBW
Minimize FiO2: <30%
Individualized PEEP: 30% of BMI
Alveolar recruitment maneuvers
Inspiratory: expiratory (I:E) ratio: 1:1.5
114
Q

Lung protective ventilation emergence settings include

A

FiO2 <80%
elevate head of bed
positive pressure ventilation- maintenance of lung volume, must be greater than closing pressure

115
Q

The goal of induction strategies include

A

attenuate anesthesia related changes

116
Q

Induction strategies include

A

initial FiO2: 100%
elevated HOB >30%; reverse trendelenburg> back up
tightly sealed face mask- apply CPAP- use APL valve or CPAP mode on ventilator
OPA or NPA as needed

117
Q

Goals of lung protective ventilation include

A

restore lung volume- alveolar recruitment maneuver (ARM)
maintain lung volume and minimize atelectasis formation- individualize PEEP
maximize lung compliance- use lowest possible driving pressure, compliance= Vt/delta P

118
Q

Tidal volume purpose:

A

maintain physiologic tidal volume

initial setting: 6-8 mL/kg IBW

119
Q

Maintenance of FiO2 is

A

initial setting: 30%
Maintain SpO2 >94%
Purpose is to reduce resorption atelectasis & use SpO2:FiO2 curve as monitor to assess if we are maintaining “open lung” ventilation

120
Q

Maintenance fiO2 should be

A

low FiO2 can be used as a surrogate monitor to assess ventilation
at 21% if saturation less than 97%, we know greater than 10% intrapulmonary shunting is occurring

121
Q

The purpose of alveolar recruitment maneuvers is to

A

create open-lung state

122
Q

Post-intubation alveolar recruitment maneuvers include

A

sufficient CPAP to exceed critical opening pressure

initial performance

123
Q

Alveolar recruitment maneuvers include

A

bag squeezing technique- ARM through ventilator is ideal

vital capacity maneuver

124
Q

The initial PEEP setting is

A

BMI x 0.3

125
Q

The purpose of the PEEP setting is to

A

maintain end expiratory lung volume, reduce atelectasis formation
BMI specific levels of PEEP must be proceeded by ARM or barotrauma may occur

126
Q

Minimum recruitment pressure required for a BMI <30

A

is 40 cmH20

127
Q

Minimum recruitment pressure required for a BMI of 30-40

A

40-50 cmH2O

128
Q

Minimum recruitment pressure required for a BMI of 40-50

A

50-55 cmH2O

129
Q

Minimum recruitment pressure required for a BMI of >50

A

50-60 cmH2O

130
Q

The initial I:E ratio setting for BMI <45 is

A

1:1.5

131
Q

The initial I:E ratio setting for BMI >45

A

1:1

132
Q

The purpose of the I:E ratio is to

A

reduce airway pressures and increase homogenous ventilation

133
Q

The goals of emergence include

A

maintain open-lung throughout emergence

minimize anesthesia induced changes during postoperative period

134
Q

The emergence FiO2 is:

A

maintain FiO2 <80% throughout

purpose: reduce atelectasis formation

135
Q

Positive pressure ventilation is used to

A

maintain CPAP and PEEP throughout

purpose: prevent atelectasis formation, maintain open-lung state

136
Q

During emergence, the head of bed should be

A

> 30 degrees in order to decrease chest wall compression and increase lung compliance

137
Q

Concerns with using excessive O2 include

A

activation of reactive oxygen species, peripheral/coronary vasoconstriction, decreased cardiac output, absorption atelectasis

138
Q

Monitoring trends includes:

A

lung compliance, pressure volume loops, and flow volume loops

139
Q

The pressure volume loop is an

A

assessment of driving pressure- pressure required to deliver set volume
want to maximize volume delivered at lowest pressure

140
Q

The flow volume loop is a

A

representation of expiratory flow

acute angle represents expiratory flow limitation

141
Q

lung compliance trending is

A

the trend of compliance throughout the case