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Block 2 week 7 > Gas exchange > Flashcards

Gas exchange Flashcards

1
Q

What two things does PaO2 depend on?

A

PAO2 and architecture of the lungs

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2
Q

What are the 2 main categories for causation of hypoxemia?

A

not enough O2 getting into the alveoli

not enough O2 transferred into the capillary blood

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3
Q

How can you get not enough O2 getting into the alveoli?

A

low atmospheric pressure (PIO2) or pure hypoventilation

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4
Q

How can you get not enough o2 transferred into the capillary blood?

A

a) ventilation-perfusion mismatch
b) right-to-left shunting
c) diffusion defects
(architechure of the lung not performing well)

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5
Q

PaO2 will always be (blank) than PAO2

A

less

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6
Q

(blank) is a cause of hypoxemia and results in a decrease in PaO2 in responseto a decrease in PAO2.

A

hypoventilation

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7
Q

Can you have a normal A-a interval but be hypoventilating?

A

yes! (they go down, but down together)

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8
Q

pure hypoventilation causes (blank)

A

hypoxemia

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9
Q

If you are undergoing hypoventilation what will happen to your PaO2 and your PAO2?

A

your PaO2 will go down due to a drop in PAO2

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10
Q

what are the main problems of hypoventilation?

A

acidemia and hypercarbia; hypoxemia less of a problem

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11
Q

one cause for hypoxemia is pure (blank)

A

hypoventilation

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12
Q

Give three examples for the cause of hypovnetilation with normal lungs and no disease

A
  • depression of respiratory center via morphine or barbituates
  • diseases of the respiratory muscles- muscular dystrophy
  • extreme obesity
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13
Q

why do you have an P(A-a)O2 differnce in a normal people?

A

because lungs dont work perfectly and because there is some ‘wasted’ blood (ie not all blood gets fully oxygenated.

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14
Q

Why do you get wasted blood?

A

cuz of anatomic shunts and low region v/q ratios

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15
Q

What is an anatomic shunt?

A

it is the entry of blood into the systemic arterial system without going through ventilated areas of lungs

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16
Q

But PAO2 > PaO2 if there is any (blank)

A

anatomic shunt.

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17
Q

The mixing of unoxygenated blood with oxygenated blood is known as (blank)

A

venous admixture

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18
Q

VA (alveolar ventilation) is about the same as the (blank)rate.

A

pulmonary blood flow

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19
Q

v/q ratio is typically (blank)

A

1

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20
Q

Gas exchange depends critically on the proper matching of ventilation (V) and perfusion (Q)
Therefore gas exchange problems have to do with abnormal (blank)

A

V/Q ratios

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21
Q

What is happening if:
v/q=0?
v/q=1?
v/q= infinity

A 
shunt (ventilation is totally absent)
normal ideal (ventilation is perfectly matched to perfusion)
Dead space (perfusion is totally absent)
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22
Q

Main reason for the V/Q differences between the apex and the base of the lung is (blank).

A

gravity

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23
Q

Towards the apex of the lung the v/q ratio tends to be (blank). Towards the base, the v/q ration tends to be (blank)

A

higher

lower

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24
Q

What is the equation for total wasted blood (physiological shunt)?

A

Physiological shunt=anatomic shunt + low V/Q regions

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25
Q

What is the equation for physiological dead space/ total wasted air?

A

physiological dead space=anatomic dead space + alveolar dead space

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26
Q

Is it normal to have anatomic shunts and anataomic dead space?

A

yes

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27
Q

Is it normal to have low v/q regions and alveolar dead space?

A

yes

28
Q

A normal A-a difference of (blank) results from gravitational effects on V/Q and on anatomic shunting

A

10-15

29
Q

V/Q mismatch among different alveoli is clinically relevant.

-A large V/Q dispersion causes an (blank)

A

P(A-a)O2 difference

30
Q

(blank) is all about mixing blood of different O2 concentrations and different volumes

A

V/Q mismatch

31
Q

What is the differences in PAO2, PACO2 and V/q ratio at the apex and base of the lung?

A

increase V/q, increased PAO2 and decreased PACO2 at the apex

Decreased V/q ratio,decreased PAO2, and increased PACO2 at the base

32
Q

When the V/Q of two different units are not the same, this is called a (blank)

A

mismatch.

33
Q

PaO2 and SaO2 are (blank) proportional

A

directly

34
Q

what is the oxygen content equation?

A

CaO2=Hb X 1.34 X SaO2/100

35
Q

If the Hb is the same for mixed samples, then the CaO2 will be (blank) to the SaO2

A

proportional

36
Q

(blank) is key variable in understanding V/Q mismatch.

A

SaO2

37
Q

Hyperoxemic will effect your O2 content a lot or a little? how about hypoxemic?

A

little, a lot

38
Q

Mixing two volumes of blood with different PO2 concentrations will have a Po2 concentration in the blood that is the mean of what concentrations? Can you use the mean of the two PO2 concentrations?

A

CaO2 or SaO2

no

39
Q

If you have a shunted arterial, can the other arterial make up for it?

A

no it cannot, you will get hypoxemia

40
Q

Due to the flat shape of the oxygen binding curve, the resulting PO2 after mixing is (blank) than the mean PO2

A

lower

41
Q

Mixing unequal volumes (Q) of blood with different PO2 results in a flow-weighted average of (blank)

A

SaO2

42
Q

If you have a v/q of zero what does this mean

A

you have a shunt

43
Q

Can supplemental O2 rescue effects of perfused but not ventilated region?

A

NO

44
Q

Can supplemental oxygen rescue effects of V/Q mismatch?

A

yes

45
Q

What is the ideal V/Q ratio?

A

1

46
Q

If you have a v/q ratio of less than 1 what happens?

If you have a v/q ratio of greater than 1 what happens?

A

you will get a decrease alveolar oxygen and increase in PACO2
Increase PAO2 and decrease PACO2

47
Q

if there is a v/q mismatch between 2 alveoli, which one will win?

A

the hypoxemic one

48
Q

V/Q mismatching is a major clinical reason for (blank)

A

hypoxemia

49
Q

When you have a v/q mismatch what happens to your A-a difference?

A

it gets larger than normal

50
Q

When you have a v/q mismatch what does it reflect?

A

an intrinsic lung problem and gas exchange problem

51
Q

(blank) is the most important cause of gas exchange abnormalities in most lung diseases.

A

V/Q mismatch

52
Q

If you have increased PaCO2, hypoventilation, and a abnormal PAO2 and PaO2 interval whats happening?

A

hypoventilation plus another mechanism

53
Q

If PaCO2 isn’t increased, you have abnormal PaO2-PAO2 interval, and have a Po2 that is correctable with O2 what do you have?

A

V/Q mismatch (airway disease, interstitial lung disease, alveolar disease, pulmonary vascular disease)

54
Q

If PaCO2 isn’t increased, you have abnormal PaO2-PAO2 interval, and have a Po2 that is not correctable with O2 what do you have?

A

Shunt (alveolar collaspe, intraalveolar filling, intracardiac shunt, vascular shunt within lungs)

55
Q

Although V/Q mismatching can influence PaCO2, this effect is often overcome by an increase in (blank).

A

minute ventilation

56
Q

As long as there is sufficient (blank), PaCO2 will be unaffected by the degrees of V/Q mismatch that routinely lead to hypoxemia.

A

alveolar ventilation

57
Q

What are the mechanisms for hypoxemia?

A
  • decrease in PIO2 (high altitude, poor ventilator)
  • pure hypoventilation
  • v/q mismatch
  • shunt
58
Q

Increased (blank) can compensate for low V/Q units. Total ventilation (VE) must (blank) for this compensation

A

ventilation

increase

59
Q

Where is ventilation and blood flow the highest, at the top or bottom of lung?

A

at the bottom of lung

60
Q

Different (blank) may have widely differing amounts of ventilation and perfusion.

A

alveoli

61
Q

In normal gas exchange, there is matching of (blank) for each alveolar unit

A

ventilation and perfusion

62
Q

Alveoli with increased perfusion also have increased (blank)

Alveoli with decreased perfusion also have decreased (blank)

A

ventilation

ventilation

63
Q

What are these symptoms of
Impaired judgment
Motor incoordination
Clinical picture closely resembling that of acute alcoholism

A

acute hypoxia

64
Q 
What are these symptoms of:
Fatigue, drowsiness
Apathy
Inattentiveness
Delayed reaction time
Reduced work capacity
A

long-standing hypoxia

65
Q

What is this?
Lower than normal PaO2 for a person’s age
Low CaO2

A

hypoxemia

66
Q

What do you use to determine hypoxemia?

A

ABG (PaO2,PaCO2) PAO2 and P(A-a) O2 difference

Block 2 week 7 (9 decks)

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