Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CVPR > CVPR Week 6: Hypoxemia > Flashcards

CVPR Week 6: Hypoxemia Flashcards

1
Q

Objectives

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

describe O2 transport throughout the body

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

describe O2 transport throughout the body

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

Atmospheric gaseous composition

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

low PaO2 in the blood is

A

arterial hypoxemia

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

arterial hypoxemia is defined by?

A

low PaO2 in the blood

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

arterial hypoxemia defect in?

2 listed

A
  • Breathing
  • Pulmonary O2 diffusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

inadequate blood flow

A

hypoperfusion hypoxia

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

hypoperfusion hypoxia is defined by?

A

inadequate blood flow

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

hypoperfusion hypoxia defect in

A

circulatory O2 delivery

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

Insufficient Hb

A

Anemic hypoxia

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

Anemic hypoxia is defined by?

A

insufficient Hb

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

Anemic hypoxia defect in?

A

O2 carrying capacity

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

Decreased cellular metabolism

A

Histotoxic hypoxia

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

Histotoxic hypoxia is defined by?

A

decreased cellular metabolism

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

Histotoxic hypoxia defect in?

A

tissue O2 utilization

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

defect in tissue O2 utilization

A

histotoxic hypoxia

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

defect in O2 carrying capacity

A

anemic hypoxia

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

Defect in circulatory O2 delivery

A

hypoperfusion hypoxia

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

Defect in pulmonary O2 diffusion

A

arterial hypoxemia

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

defect in breathing

A

arterial hypoxemia

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

arterial hypoxemia always results in?

A

Low PaO2 in blood

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

Identify

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

Identify

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

Identify

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

hypoperfusion hypoxia is a defect of

A

inadequate blood flow

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

generalized hypoperfusion is referred to as?

A

Shock

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

Shock is referred to as?

A

generalized hypoperfusion

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

global decrease in blood flow is associated with?

A

decreases in MABP

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

MAP =

A

CO X TPR = MAP

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

Types of circulatory shock

3 listed

A
  • Septic shock
  • Anaphylactic shock
  • neurogenic shock
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Neurogenic shock is caused by?

A

failure of the autonomic nervous system to control peripheral resistance

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

Anaphylactic shock is caused by?

A

severe allergic reaction and massive cytokine release causing global vasodilation and massive pressure loss

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

Septic shock cause

A

infection in the blood causes a massive immune response and cytokine release leading to massive global vasodilation and loss in pressure and resistance

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

Causes of cardiogenic shock

A
  • Arrhythmias
  • Heart failure
  • Autonomic failure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

CO =

A

SV x HR = CO

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

Causes of hypovolemic shock

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

Hypoperfusion hypoxia O2 values

A
  • normal PaO2 because lungs are diffusing fine
  • lower PvO2 because the tissues extract what they can
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Describe the O2 environment in Hypoperfusion hypoxia

A
  • Normal PaO2
  • Low PvO2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Regional hypoperfusion is referred to as?

A

Ischemia

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

Ischemia is?

A

regional hypoperfusion

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

Explain this graph

A

if the autoregulatory mechanism is impaired somehow then this leads to subnormal flow and ischemia

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

Anemic hypoxia is a defect in?

A

Insufficient hemoglobin or impaired hemoglobin

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

Insufficient or impaired hemoglobin results in

A

reduced oxygen-carrying ability due to the loss of red blood cells (says the slide)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

O2 values of anemic hypoxia

A
  • Normal PaO2
  • Low CaO2
  • Low PvO2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Describe the O2 environment of anemic hypoxia

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

Causes of Anemia

5 listed

A
  • genetic
  • hemorrhage
  • autoimmune
  • nutritional deficiency (iron, vit B12, folate)
  • bone marrow destruction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

PO2 in the blood in

  1. Polycythemia
  2. Normal
  3. Anemia
  4. Carbon monoxide poisoning
A
  • Doesn’t change the PO2 in the blood but instead binds more or less O2 depending on the amount of Hb present
  • It changes the total O2 content and not the PaO2
  • Carbon monoxide poisoning binds to Hb with greater affinity than O2 does which lower the amount of Hb for O2 to bind to
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Histotoxic hypoxia is a defect involving

A

reduced cellular usage of O2

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

Some causes of Histotoxic hypoxia

A
  • Cyanide poisoning
  • Sulfide poisoning
  • Narcotics (barbiturates)
  • Vitamin B, deficiency or Beriberi
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Histotoxic hypoxia O2 values

A
  • Normal PaO2 because perfused normally
  • High PvO2 because O2 isn’t being used up by the tissues normally
  • Low VO2 because
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Describe the O2 environment of Histotoxic hypoxia

A
  • Normal PaO2
  • High PvO2
  • Low VO2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Classifications of hypoxemia

3 listed

A
  • Mild 60-80 mmHg or >95% SaO2
  • Moderate 46-60 mmHB or 75-90% SaO2
  • Severe < 40 mmHg or < 75% SaO2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Mild hypoxemia symptoms

A
  • May be unnoticeable
  • increased pulse and breathing rate
  • impaired thinking and attention
  • reduced coordination
55
Q

Mild hypoxemia lab values

A
  • 60 - 80 mmHg
  • 90 - 94% SaO2
56
Q

Moderate hypoxemia symptoms

5 listed

A
  • Drowsiness
  • headache
  • mental and muscle fatigue
  • faulty coordination
  • poor judgement
57
Q

Moderate hypoxemia lab values

A
  • 40 - 60 mmHg PO2
  • 75 - 90% SaO2
58
Q

Severe hypoxemia symptoms

5 listed

A
  • seizure and muscle twitching
  • very poor judgement and coordination
  • impaired respiration
  • nausea
  • vomiting
59
Q

Severe hypoxemia lab values

A
  • PO2 < 40 mmHg down around 30 pass out, down around 20 basically dead
  • SaO2 < 75%
60
Q

what is the interpretation of V/Q

A

the balance between O2 delivery to alveoli (V) and the O2 removal by the blood (Q)

61
Q

Ideal V/Q vs Healthy Actual V/Q

A

Ideal V/Q = 1

Actual V/Q = 0.8

62
Q

V/Q =

A

ventilation / perfusion

63
Q

Normal PO2s and PCO2s in pulmonary arteries capillaries veins alveoli and environmental air

A
64
Q

A-a gradient =

equation

A

A-a gradient = PAO2 - PaO2

65
Q

typical A-a gradient

A

100 PAO2 to - 92 PaO2

usually about 5 to 10 mmHg difference

increases as you age

66
Q

A-a gradient interpretations relative to the cause of hypoxemia

A
  • if A-a gradient = 5-10 mmHg then the cause is usually due to high altitude or hypoventilation
  • If A-a gradient = increased then this is due to at least on or a combination of V/Q mismatch, impaired diffusion, and/or shunt
67
Q

Increased A-a gradient causes

3 listed

A

at least one of these or a combination of them V/Q mismatch, impaired diffusion, and/or shunt

68
Q

How to measure alveolar PAO2

A

the alveolar gas equation

69
Q

Alveolar gas equation

A

FiO2 (Patm - PH2O) - [PaCO2/RQ]

PH2O is the water vapor pressure from the humidifying of the air while breathing it in

FiO2 = the atmospheric PO2

so FiO2(Patm - PH2O) = inspired air

so

inspired air - perfused air going out

PaCO2 is the arterial blood gas pressure

RQ = respiratory quotient

70
Q

The typical difference between Air and alveolar PO2 is about?

A

~ 10 mmHg

71
Q

RQ =`

A

respiratory quotient explained

72
Q

RQ interpretation

A

the respiratory quotient

typically = 0.8

interpreted as

for every 8 molecules of CO2 made it took 10 molecules of O2 to make it

73
Q

PaCO2 / RQ =

A

basically O2 in the pulmonary capillaries / tissue usage

74
Q

How altitude effects PAO2

A

the only thing that changes is the atmospheric PO2 which thereby reduces PAO2

75
Q

Adaptation to high altitude and PAO2

A

since we are highly adapted to high elevation the PCO2 is a little bit lower and so the PAO2 os actually a little bit higher

76
Q

sensors of low PaO2

A

carotid body chemoreceptors

77
Q

Effects of low PaO2

4 listed

A
  • increase HR
  • increases ventilation
  • constricts pulmonary arteries
  • dilates systemic arteries to attempt to deliver as much oxygen as possible
78
Q

Acute Protective mechanisms against hypoxemia

4 listed

A
  • increase HR
  • increases ventilation
  • constricts pulmonary arteries
  • dilates systemic arteries to attempt to deliver as much oxygen as possible
79
Q

how is increasing ventilation protective against hypoxemia

A
  • you would have reduced resistance to hypoxemia with lower atmospheric O2
80
Q

Ventilation effects on PAO2 and PAO2

A
81
Q

Increasing PACO2 does what to PAO2

A

the amount of CO2 reduces the amount of O2 can be in there at one time

82
Q

Usual causes of hypoventilation

4 listed

A
  • Depressed CNS (drug overdose or CNS lesion)
  • Nerve conduction defects (Guillain-Barre, spinal cord injury or phrenic nerve paralysis)
  • Lung disease (sleep apnea, obesity)
  • Respiratory Muscle weakness (muscular dystrophy, myasthenia gravis or hypothyroidism)
83
Q

Typical CNS causes of hypoventilation

2 listed

A
  • drug overdose
  • CNS lesion
84
Q

Typical causes of nerve conduction defects resulting in hypoventilation

3 listed

A
  • Guillian-Barre
  • spinal cord injury
  • phrenic nerve paralysis
85
Q

Typical causes of lung disease defects resulting in hypoventilation

2 listed

A
  • sleep apnea
  • obesity
86
Q

Typical causes of muscle weakness defects resulting in hypoventilation

3 listed

A
  • Muscular dystrophy
  • myasthenia gravis
  • hypothyroidism
87
Q

Identify

A
88
Q

Identify

A
89
Q

A-a gradient of hypoventilation

A

Hypoventilation results in a normal A-a gradient because there’s nothing wrong with the amount of atmospheric oxygen or its ability to perfuse the problem lies in the amount and frequency of ventilation

However, there is CO2 dilution from the reduced ventilation but this doesn’t affect the A-a gradient because the CO2 will be in the PACO2

90
Q

How can hypoventilation or high altitude hypoxemia be corrected?

A

increasing FiO2

so basically increase the oxygen concentration of the air to be inspired FiO2

an easy way to do this is using supplemental O2

However, with hypoventilation, the hypercapnia will still persist due to the reduced breathing rate so the reduced ability to dump CO2

91
Q

Increasing FiO2 in hypoventilation

A

the PAO2 will rise however the hypercapnia will remain because of the reduced ventilation so PACO2 will remain high

92
Q

The normal A-a gradient is due to

A

some amount of natural V/Q mismatch that occurs and some degree of shunt which will account for the 5-10 mmHg gradient

93
Q

Natural V/Q mismatch

A

gravity is a cause because blood and air are not equally distributed throughout the lung

  • Zone 1 is the superior apex of the lung where more ventilation than perfusion occurs
  • in Zone 2
  • In Zone 3
94
Q

Zone 1 of the lung

A

more V than Q

↑V/↓Q = ↑1

PA>Pa>Pv

95
Q

Zone 2 of the lung

A

V and Q are pretty equally matched

so

V/Q = ~ 1

Pa>PA>Pv

96
Q

Zone 3 of the lung

A

Less V and more Q

↓V/↑Q = ↓1

Pa>Pv>PA

97
Q

The effect of V/Q mismatching on PAO2 and PACO2

A

Low V/Q =

↓ PAO2

↑PACO2

High V/Q =

↑PAO2

↓PACO2

98
Q

When V/Q = 0

A

referred to as R-L shunt

and the concentrations of PACO2 and PAO2 will be very close to mixed venous blood

99
Q

When V/Q = ∞

A

referred to as Deadspace

and the concentrations of PACO2 and PAO2 will be very close to inspired air

100
Q

Compensatory mechanisms for V/Q mismatch

2 listed

A
  • Vasoconstriction
  • Bronchiolar constriction
101
Q

Bronchial constriction airways in response to V/Q mismatching

A

↑PO2 but ↓ PCO2 and an ↑pH around smooth muscle in the bronchials causes contriction of airflow to better perfused areas

102
Q

Response of bronchials to reduced perfusion

A

↓ blood flow causes type II pneumocytes to produce less surfactant causing ↓ compliance and ventilation so the alveoli shrink

103
Q

Vasoconstriction in response to V/Q mismatching

A

in response to local alveolar hypoxia, the arterioles feeding the alveoli constrict (hypoxic vasoconstriction) diverting blood to better-ventilated areas

104
Q

Increased V/Q mismatch interpretation

A

When V/Q = > 1

blockade of perfusion but increased ventilation

105
Q

Decreased V/Q mismatch interpretation

A
  • when V/Q = < 1
  • Reduced ventilation but increased perfusion
106
Q

Increased V/Q mismatch compensation

2 listed

A

↑PO2 but ↓ PCO2 and an ↑pH around smooth muscle in the bronchials causes contriction of airflow to better perfused areas

also

↓ blood flow causes type II pneumocytes to produce less surfactant causing ↓ compliance and ventilation so the alveoli shrink

107
Q

Decreased V/Q mismatch compensation

A

in response to local alveolar hypoxia, the arterioles feeding the alveoli constrict (hypoxic vasoconstriction) diverting blood to better-ventilated areas

108
Q

Types of R to L shunts

2 listed

A
  • Anatomical shunts
  • Intrapulmonary shunts
109
Q

Anatomical shunt description

A

blood that does not traverse the pulmonary capillaries

110
Q

Normal anatomical shunts

A

coronary circulation

blood goes from the left heart to the coronary circulation and back into the left heart

Bronchial circulation

Actually part of the systemic circulation and carries blood that supplies the lung with O2 and gets dumped back into the lung through the bronchial vein past the pulmonary arteries so it is not oxygenated by the alveoli directly

111
Q

Identify

A
112
Q

Intrapulmonary shunt description

A

blood traverses pulmonary capillaries that are adjacent to unventilated or poorly ventilated alveoli

113
Q

Absolute or true intrapulmonary shunt

A

V/Q = 0

114
Q

Shunt-like intrapulmonary shunt

A

Low V/Q

115
Q

Normal shunts account for how much of the cardiac output?

A

2 - 5 % of the CO

116
Q

A-a gradient genesis

A
  • anatomical shunts (pulmonary and bronchial circulations)
  • Gravity (non-uniform ventilation and perfusion distribution)
117
Q

Shunt-like effects are usually due to?

A

Diffusional impairment or diffusional limitations where Fick’s law of diffusion is manipulated

118
Q

Examples of causes of diffusional impairment

6 listed

A
  • Atelectasis/Pneumothorax
  • Emphysema alveolar-capillary destruction
  • Interstitial edema fluid accumulation
  • Alveolar fibrosis thickening of the alveolar wall
  • Pneumonia alveolar inflammation
  • Pulmonary edema fluid accumulation
119
Q

Emphysema shunt-like state

A

destruction of alveoli and capillaries reducing the surface area available for diffusion

120
Q

Alveolar fibrosis cause of shunt-like state

A

thickening of the alveolar wall which decreases diffusion

121
Q

Pneumonia cause of shunt-like state

A

alveolar inflammation or edema interfering with diffusion

122
Q

Interstitial edema cause of shunt-like state

A

fluid accumulation in between the capillary and the alveoli interfering with diffusion

123
Q

Atelectasis cause of shunt-like state

A

the collapse of alveoli reduces ventilation and therefore diffusion capabilities

124
Q

Pneumothorax cause of shunt-like state

A

collapse of the lung prevents alveolar filling and therefore interferes with diffusion

125
Q

How are shunts graded?

A

the degree of shunts is determined by the effectiveness of supplementary O2

126
Q

What is the cut-off for supplemental O2 effectiveness for shunts?

A

~30% anything more than that and supplemental O2 will not be effective

127
Q

Exercise and the identification of diffusional limitations

A
  • A-a gradient can seem normal at baseline resting conditions but exercise can unmask diffusional limitations
  • Reduced perfusion time in the capillaries as a result of exercise may expose diffusional limitations that might otherwise go unnoticed
128
Q

exercise diffusional limitations

A
129
Q

Summary I

A
130
Q

Summary 2

A
131
Q

Question

A
132
Q

Question

A
133
Q

Question

A
134
Q

Question

A

CVPR (93 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions