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CPR > Ventilation - Perfusion Relationship (Part 2) > Flashcards

Ventilation - Perfusion Relationship (Part 2) Flashcards

1
Q

What does the Alveolar Gas Equation allow you to calculate?

A

The oxygen concentration in the alveoli

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2
Q

Once you know the oxygen concentration in the alveoli, (and you know the oxygen concentration in the arteries), what can you calculate?

A

A - a oxygen gradient

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3
Q

What does the A - a oxygen gradient determine?

A

The health of the alveoli

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4
Q

Normally, the A - a oxygen gradient should be around what value?

A

20 mm Hg

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5
Q

What is the Alveolar Gas Equation?

A

PAo2 = PIo2 - (Paco2/RQ)

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6
Q

What is PAo2?

A

Oxygen concentration in the alveoli

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7
Q

What is PIo2?

A

Partial pressure of oxygen in inspired air

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8
Q

What must the PIo2 account for?

A

Water vapor

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9
Q

What is the equation to calculate PIo2?

A

(760 - 47) X oxygen%

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10
Q

Normal water vapor value?

A

47

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11
Q

Normal oxygen percentage of inspired air?

A

21%

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12
Q

What is RQ?

A

Respiratory Quotient

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13
Q

What is a normal value of RQ?

A

0.8

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14
Q

What is the equation for RQ?

A

Volume of CO2 produced/Volume of O2 consumed

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15
Q

If you are breathing room air, what is the equation for PIo2?

A

(760 - 47) X 21%

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16
Q

What is the equation for A - a oxygen gradient?

A

PAo2 - Pa02

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17
Q

If there is an increase in the A - a oxygen gradient, what does this mean?

A

There is a diffusion impairment at the alveoli

>20mmHg

18
Q

What is a normal value for Intrapleural Pressure?

A
  • 5 mmHg
19
Q

At the apex of the lung, what is the amount of Intrapleural Fluid?

A

LOW

- due to gravity

20
Q

At the apex of the lung, what is the level of the Intrapleural Pressure?

A

LOWER - MORE Negative

21
Q

At the apex of the lung, what are the sizes of the alveoli?

A

LARGER

22
Q

Since the alveoli are larger at the apex of the lung, with inspiration, can they grow much in size?

A

No

23
Q

At the base of the lung, what is the amount of Intrapleural Fluid?

A

HIGH

- due to gravity it pools there

24
Q

At the base of the lung, what is the level of the Intrapleural Pressure?

A

HIGHER - LESS negative

25
Q

At the base of the lung, what are the sizes of the alveoli?

A

SMALL

26
Q

Since the alveoli are smaller at the base of the lung, with inspiration, can they grow much in size?

A

YES

27
Q

Where are alveoli the largest?

A

Apex of the lung

28
Q

Where are alveoli the smallest?

A

Base of the lung

29
Q

What is a V/Q ratio?

A

Ventilation/Perfusion ratio

30
Q

What is a normal V/Q?

A

0.8

31
Q

High V/Q means?

A

Ventilation is HIGH compared to a normal perfusion

32
Q

Low V/Q means?

A

Ventilation is LOW compared to a normal perfusion

33
Q

With a Low V/Q, what happens with time?

A

Low ventilation - the alveoli will equilibriate with the blood due to no oxygen coming into the lungs
= PO2 = 40; PCO2 = 45;
NO GAS EXCHANGE WILL OCCUR

34
Q

With a Low V/Q, what do you expect the Pa of O2 and CO2 to be in arterial blood?

A 
PaO2 = 40mmHg (low)
PaCO2 = 45mmHg (high)
35
Q

With a High V/Q, what happens with time?

A 
Low perfusion (blood flow) - the alveoli will equilibriate with the atmosphere due to no exchange occurring with blood
= PO2 = 150; PCO2 = 1
Little effects on the blood since there isn't much arriving there
36
Q

With a High V/Q, what do you expect the Pa of O2 and CO2 to be in the little arterial blood that does arrive there?

A 
PaO2 = 150mmHg (high)
PaCO2 = 1mmHg (low)
37
Q

What downstream effects does a High V/Q have on a normal alvelous?

A

It will turn it into a LOW V/Q situation by increasing the blood flow (perfusion) to that area

38
Q

The apex of the lung has a ____ V/Q

A

HIGH

39
Q

The middle of the lung has a ____ V/Q

A

Normal - 0.8

40
Q

The base of the lung has a ____ V/Q

A

LOW

CPR (48 decks)

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