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SF3 Pulm Test > Dasgupta - V/Q Matching > Flashcards

Dasgupta - V/Q Matching Flashcards

1
Q

Normal V/Q ratio in a normal adult whole lung

A

O.8

3600/4500

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2
Q

What are the two pumps involved in the pulmonary system?

A

The heart pumps blood into the lung

The chest wall pumps air into the lung

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3
Q

Areas with blood flow but no ventilation. Pure mixed systemic venous blood

A

Shunt

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4
Q

Areas with ventilation but no blood flow

A

Dead space

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5
Q

The more extreme the V/Q mismatch is, the _____ the gas exchange is

A

Worse

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6
Q

The efficiency in gas exchange is dependent on which 3 things?

A

High gradient in partial pressure

Low thickness of membrane (~0.5 micron)

High surface area of alveolus

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7
Q

PAO2 =

A

PO2 in alveolar gas

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8
Q

PaO2 = PO2 in _____

A

Systemic arterial blood

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9
Q

The bigger the A-a difference is, the _________ the exchange

A

Poorer

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10
Q

A measure of whether optimal V/Q matching is occurring in the lung

A

A-a gradient

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11
Q

What causes the normal low V/Q ratio in the bottom of the lung and high V/Q ratio in the top of the lung?

A

The gradient of Q from gravity is much greater than that of V.

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12
Q

The greater Q is in relation to V, the _____ the PCO2 will be

A

Higher

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13
Q

V/Q is _______ to PaO2

A

Directly proportional

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14
Q

The higher the V/Q, the _____ the PaO2

A

Higher

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15
Q

PCO2 of venous blood = ??

This is what PACO2 of alveoli reaches when it is perfused but not ventilated

A

46mm Hg

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16
Q

A ____ of the V/Q ration will increase the PO2

A

Increase

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17
Q

The lung unit with low V/Q will have ____ PO2 and ____ PCO2

A

Low

High

18
Q

The lung unit with high V/Q will have ____ PO2 and _____ PCO2

A

High

Low

19
Q

Nitric oxide ______ hypoxic pulmonary vasoconstriction

A

Reverses

20
Q

Why is inhaled NO more effective at reducing hypoxic pulmonary vasoconstriction than ingested NTG and NTP?

A

The inhaled NO only goes to the alveoli that are ventilated and dilating the blood vessels there. Instead of going to all lung segments like NTG and NTP would do.

21
Q

Required concentration of NO for therapy?

A

20ppm

*NO is very toxic at high concentrations

22
Q

Shunt-like states are said to be ____ V/Q mismatch

A

Low

23
Q

______ are the most dangerous V/Q mismatch

A

Low V/Q mismatches

Because these units are shunt-like

24
Q

Low V/Q mismatch results in ______ _

A

Hypoxemia

High A-a gradient

High PCO2 in arterial blood

25
Q

Low pCO2 in airways causes the airways to ________

A

Constrict locally

26
Q

Paradox of compensation in low V/Q patients

A

PaCO2 is normal

PaO2 is low

27
Q

Things that limit ventilation:

A

Obstructive lung disease (emphysema, bronchitis, asthma)

Shunt (alveoli filled with fluid or foreign material)

Restrictive lung disease (fibrosis)

28
Q

Pneumonia of the lungs is a classic example of a ______

A

Shunt

29
Q

Normal A-a gradients

A

5-15mmHg

This one is according to dasgupta, BRS has a different number

30
Q

The fact that there is a normal A-a gradient that is more that 0 is because of ?

A

V/Q mismatching [due to gravity in normal lungs]

Shunts [all lungs have shunts in the form of venous drainage of parts of the heart and large airways]

31
Q

The older you are, the _____ your A-a gradient will be.

A

Larger

32
Q

Normal range per A-a gradient increases _______ per decade after age 30

A

3mmHg

33
Q

Five causes for hypoxemia

A

Breathing air w/ low pO2

Hypoventilation

Shunts

Low V/Q mismatch

Diffusion problem

34
Q

Hypoventilation always results in _____ and ______

A

Hypoxemia

Hypercapnia

(A-a gradient normal)

35
Q

Patient presents with hypoxemia.

Shows only small increase in PaO2 when 100% O2 is administered.

A-a gradient is large.

Likely diagnosis is?

A

Shunts

36
Q

Cause of hypoxemia.

Also associated with hypercapnia.

A-a gradient is normal

A

Hypoventilation

37
Q

Pt presents w/ hypoxemia. Shows marked increase in PaO2 when 100% O2 administered.

A-a gradient is large

A

Low V/Q mismatches

38
Q

Cause of hypoxemia.

Shows marked increase in PaO2 when 100% O2 administered.

A-a gradient large.

This type is very uncommon and must be differentiated with more diagnostic methods

A

Diffusion defects

39
Q

Problems of a pulmonary embolus are initially ______

A

Cardiovascular.

Right heart has to work harder to move CO thru remaining sections of lungs.

40
Q

V but no Q

A

Dead space

41
Q

Q but no V

A

Shunt

SF3 Pulm Test (10 decks)

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