Ventilation Perfusion relationships Flashcards Preview

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Flashcards in Ventilation Perfusion relationships Deck (48)
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1

Distribution of ventilation (awake, upright, spont):

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

Non-dependent  (apex) more subatmospheric

Dependent (base) less Subatmospheric

 

2

Distribution of ventilation (awake, upright, spont):

with END-Inspiration what are in more and less subatmspheric

non-dependent more subatmospheric

Dependent less subatmospheric

3

Distribution of ventilation (awake, upright, spont):

ventilation = what?

change in volume

4

Distribution of ventilation (awake, upright, spont):

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

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

Distribution of ventilation (awake, upright, spont):

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

 

6

what is normal V/Q mismatch and why?

0.8

Normal MV is 4L/min

Normal CO is 5L/min

4 / 5 = 0.8

7

Distribution of ventilation (awake, upright, spont):

so where is ventilation the best in this pt

dependent lung

8

Distribution of Perfusion (awake, upright, spont):

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

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

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

picture to explain why perfusion is best in bases

 

10

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

so where is perfusion best in this pt?

dependent bases

11

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

 

12

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

Same is in the upright pt. 

dependent lung always the down lung

13

Distribution of V/Q: Lateral anesthetized & paralyzed:

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

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

Distribution of V/Q: Lateral anesthetized & paralyzed:

picture to explain it visually

 

15

Ventilation and Perfusion Lateral Decubitis Summary

Label the chart

 

16

V/Q mismatches:

if you have no ventilation and only perfusion what is it

Absolut shunt

V / Q

O / 5 = 0

 

17

V/Q mismatches:

what is teh numerical value for shunt?

0

18

V/Q mismatches:

what is normal V/Q and explain

0.8 

V / Q

4 / 5 = 0.8

19

V/Q mismatches:

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

Dead space

V / Q

4 / 0 = infinity

20

V/Q mismatches:

what is the numerical value for Deadspace?

infinity

21

V/Q mismatches:

what is a dead unit?

no ventilation and no perfusion

22

V/Q mismatches:

picture to show

 

23

V/Q mismatches:

whata are 3 causes of low PaO2

low inspired O2

Hypoventilation

V/Q mismatch

24

V/Q mismatches:

the pt is hypoxemic (PaO2

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

PAO2 - PaO2

 

25

PAO2 - PaO2 gradient:

what is the normal gradient PAO2 - PaO2 ?

5-15mmHg

26

PAO2 - PaO2 gradient:

What is normal PaCO2 - PACO2 gradient

 

2-10 mmHg

 

27

PAO2 - PaO2 gradient:

if either ration is increased what does this mean?

there is a V/Q mismatch

28

PAO2 - PaO2 gradient:

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

29

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?

55-45 = 10

normal ratio so Hypoventilation

30

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

62- 28 = 34 mmHg

abnormal so V/Q mismatch

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