Ventilation Perfusion relationships Flashcards Preview

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Flashcards in Ventilation Perfusion relationships Deck (48)
1
Q

Distribution of ventilation (awake, upright, spont):

during END-expiration. what area of the lung is more subatmospheric and what area is less subatmospheric

A

Non-dependent (apex) more subatmospheric

Dependent (base) less Subatmospheric

2
Q

Distribution of ventilation (awake, upright, spont):

with END-Inspiration what are in more and less subatmspheric

A

non-dependent more subatmospheric

Dependent less subatmospheric

3
Q

Distribution of ventilation (awake, upright, spont):

ventilation = what?

A

change in volume

4
Q

Distribution of ventilation (awake, upright, spont):

since ventilation is a change in volume… where is ventilation the best in this patient???? and why?

A

the dependent lung

b/c there is teh biggest change in volume done there. the alveoli went from empty to full. and the non-dependent alveoli went from 1/2 full to full. see picture on next slide

5
Q

Distribution of ventilation (awake, upright, spont):

picture of why ventilation is best in the dependent lung of this pt

A
6
Q

what is normal V/Q mismatch and why?

A

0.8

Normal MV is 4L/min

Normal CO is 5L/min

4 / 5 = 0.8

7
Q

Distribution of ventilation (awake, upright, spont):

so where is ventilation the best in this pt

A

dependent lung

8
Q

Distribution of Perfusion (awake, upright, spont):

where is perfusion the best during end -expiration at and why?

A

the dependent lung

b/c the alveoi are smaller and gets best blood flow

in the non-dependent lung the alveoli are large and compress the vasculature.

ex nondependent has a V/Q of 3.5

where dependent has V/Q of 0.6

(see picture on next slide)

9
Q

Distribution of Perfusion (awake, upright, spont):​

picture to explain why perfusion is best in bases

A
10
Q

Distribution of Perfusion (awake, upright, spont):​

so where is perfusion best in this pt?

A

dependent bases

11
Q

in the diagram show how Intrapleural pressure, Ventilation, perfusion, V/Q mismatch, PaO2 and PaCO2 differ in the dependent and non-dependent lung.

pt is upright and spont breathing

A
12
Q

Distribution of V/Q: Lateral Decubitus UNanesthetized:

in the spont breathing pt in lateral decubitus, what happens to the V and Q in the lungs to the dependent and non-dependent lungs

A

Same is in the upright pt.

dependent lung always the down lung

13
Q

Distribution of V/Q: Lateral anesthetized & paralyzed:

what happens to V and Q and V/Q mismatch here? and why?

A

Ventilation best to NON-dependent (up) lung

Perfusion best to Dependent lung (down)

Increased V/Q mismatching

the dependent lung becomes compressed by the abd contents. with positive pressure ventilatin, inspiratory gases are preferentaly distributed to the NON-dependent lung. A clinically significant mismatch in V/Q develops. The NON-dependent lung is well ventilated but poorly perfused (deadspace), and the dependent lung is poorly ventilated and well perfused (shunting)

See pic on next slide to clearify

14
Q

Distribution of V/Q: Lateral anesthetized & paralyzed:

picture to explain it visually

A
15
Q

Ventilation and Perfusion Lateral Decubitis Summary

Label the chart

A
16
Q

V/Q mismatches:

if you have no ventilation and only perfusion what is it

A

Absolut shunt

V / Q

O / 5 = 0

17
Q

V/Q mismatches:

what is teh numerical value for shunt?

A

0

18
Q

V/Q mismatches:

what is normal V/Q and explain

A

0.8

V / Q

4 / 5 = 0.8

19
Q

V/Q mismatches:

if you have ventilation and no perfusion what is it called?

A

V / Q

4 / 0 = infinity

20
Q

V/Q mismatches:

what is the numerical value for Deadspace?

A

infinity

21
Q

V/Q mismatches:

A

no ventilation and no perfusion

22
Q

V/Q mismatches:

picture to show

A
23
Q

V/Q mismatches:

whata are 3 causes of low PaO2

A

low inspired O2

Hypoventilation

V/Q mismatch

24
Q

V/Q mismatches:

the pt is hypoxemic (PaO2

A

you must calulate and interperate the Alveolar - arterial blood gradient for O2 and/or Co2

PAO2 - PaO2

25
Q

what is the normal gradient PAO2 - PaO2 ?

A

5-15mmHg

26
Q

What is normal PaCO2 - PACO2 gradient

A

2-10 mmHg

27
Q

if either ration is increased what does this mean?

A

there is a V/Q mismatch

28
Q

what is normal PAO2 -PaO2 gradient on 100% room air

A
29
Q

Problems:

while breathing room air a pt has a PaCO2 of 76mmHg a PAO2 of 55mmHg and a PaO2 of 45mHg. what is the problem V/Q mismatch or hypoventilation?

A

55-45 = 10

normal ratio so Hypoventilation

30
Q

Problems:

a pt who is mechanically ventilated has a PaCO2 62 mmHg, and an ETCO2 28mmHg, and a PaO2 of 50mmHg. what is the problem V/Q or hypoventilation

A

62- 28 = 34 mmHg

abnormal so V/Q mismatch

31
Q

Problems:

how do you estimate the PaO2 in a healthy pt?

A

by multiplying the %O2 in the inspired gas by 5

32
Q

Problems:

how do u estimate the PAO2 in a healthy pt?

A

multiply the % O2 of the inspired gas mixture by 6

33
Q

Problems:

est the PaO2 and PAO2, then them do the PAO2 - PaO2 gradient if the pt is breathing an FiO2 of 0.6 (60%)

A

PaO2 = 60 x 5 = 300

PAO2 = 60 x 6 =360

360 - 300 = 60mmHg

34
Q

Problems:

a pt who is mechanically ventilated has a PaO2 od 250mmHg, when the inspired O2 is 100%. Does the pt have a V/Q problem?

A

PAO2 = 6 x 100 = 600

600 - 250 = 350mmHg

yes there is V/Q mismatch

35
Q

questions:

What si average V/Q

A

0.8

36
Q

questions:

what is happening if V/Q = 0

A

Shunt

right to left

37
Q

questions:

what is happening if V/Q = infinity

A

38
Q

questions:

what is the normal PAO2 -PaO2 different on room air?

on 100% O2

A

RA= 5-15 mmHg

100% =

39
Q

questions:

what is indicated if there is an increase in PAO2-PaO2 or PaCO2 - PACO2?

A

A V/Q mismatch

40
Q

questions:

what can cause Shunting

A

Asthma

CF

tumor

41
Q

questions:

A

PE

clamping

tumor

42
Q

Summary:

in any position in an AWAKE, SPONT BREATHING, UPRIGHT patient. the ______ region of the lungs are better perfused and ventilated?

A

dependent

43
Q

Summary:

why does a shunt cause a right to left shunt?

A

the blood passes to the left side of the body without being oxygenated.

44
Q

Summary:

will O2 help the situation if there is a right to left shunt?

A

no.. the alveoli are empty or blocked can’t get O2 there

45
Q

Summary:

will O2 help if the problem is hypoventilation or Dead space?

A

yes

46
Q

Summary: OLV

Do you CPAP the dependend or NON-dependent lung

A

Non-dependent

47
Q

Summary:​ OLV

do you PEEP the dependent or NON-dependent lung

A

Dependent

48
Q

Summary:​ OLV

if you can do one or the other in OLV, would it be CPAP or PEEP?

A

CPAP- it has been shown to be a better intervention