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Flashcards in Ventilation Deck (55):
1

Minute Ventilation (VE) define

volume of air flow through the lung per minute

2

Equation for Minute ventilation

mInute ventilation (VE) = tidal volume x Breathing rate

3

typical values (average sized person) for TV BR Minute ventilation (VE)

TV = 0.5 L/breath BR = 12 breaths/minute

Minute ventilation (VE) = 6L

4

define tidal volume

frequency of breathing and volume of air per breath

5

define ventilation

airflow in the lung

6

a

a

7

define alveolar ventilation (VAdot)

volume of air flow in alveolar space per minute

8

typical value for alveolar ventilation

4.2 L

9

where does gas exchange occur in the lungs

alveoli

10

Airways hold ___% of lung volume Alveoli hold ___% of lung volume

30%

70% so VE * 0.7 = VAdot

11

a

a

12

Factors that influence lung ventilation (VAdot)

1) Obstructive diseases (COPD)

2) Compliance problems (pulm fibrosis)- severe ONLY

3) exercise (incr up to 10x)

4) high altitude (low O2 level)

5) gravity

13

why does only severe compliance disease affect lung ventilation

because body has compensatory mechanisms to compensate for mild/moderate form of disease

14

why does ventilation incr with exercise

to get more O2 delivery to periphery

15

how does gravity affect ventilation

alveolus at top of lung has more gravitational forces (more weight below it) than alveolus at bottom --> gravity affects top alveolus more than bottom

16

which alveolus, top or bottom, is more affected by gravity

top --> has weight of lung below it

Vol (top alveolus) > Vol (bottom alveolus)

Vent (top alveolus) < Vent (bottom alveolus)

17

why does top alveolus have less ventilation than bottom alveolus

airflow = change in volume during ventilation cycle

smaller volume = greater possible change in volume = greater air flow and greater ventilation therefore, top alveolus LESS COMPLIANT than bottom because more gravity to incr baseline volume

18

ventilation (airflow) depends on ___ NOT ___

DEPENDS ON CHANGE IN VOLUME DURING VENTILATION CYCLE NOT ABSOLUTE ALVEOLAR VOLUME/SIZE

19

On compliance CURVE with alveolar volume vs. transpulmonary pressure where do top and bottom alveolus lie

top alveolus is further up on saturated portion so slope (compliance) is smaller bottom alveolus in mid curve

20

A

A

21

A

A

22

lung compliance and airway resistance not only affect the magnitude of air flow in the lung (ventilation) but also ____

how we breathe

23

lung compliance and airway resistance not only affect the ___ but also how we breathe

magnitude of air flow in the lung (ventilation)

24

what is the work done in the lungs? (2 types)

1) work done against elastic recoil of lungs 2) work done against airway resistance

25

if you increase elastic recoil (decr compliance), work ___ if you increase airway resistance, work ____

increases increases can be each individually or combo

26

for small tidal volumes, work to overcome elastic recoil is (small/large) work to overcome airway resistance is (small/large)

elastic recoil = small work airway resistance = large work --> when you breath at high frequency (small TV), you won't inflate lungs to large lung volumes during inspiration (small TV) - --> incr freq --> opens up airways

27

for large tidal volumes, work to overcome elastic recoil is (small/large) work to overcome airway resistance is (small/large)

elastic recoil = large work inflating lung far past intrinsic equilibrium position, and that takes lots of work --> decr freq --> MORE WORK airway resistance = small work

28

most people breathe at ___ tidal volumes why?

middle tidal volume (least amount of work)

29

based on work vs TV/freq curve, at low Freq, high tidal volume work is ____ (large/small)

large

30

based on work vs TV/freq curve, at low Freq, high tidal volume work is ____ (large/small)

alarge

31

based on work vs TV/freq curve, we breathe in what shape

we breathe at middle TV and frequency v-shaped

32

how does obstructive disease affect work vs. resistance and elastic curves?

in bronchitis/asthma, the elastic curve stays same

resistance curve shifts upwards due to incr resistance to outflow

lowest point (two curves intersect) is occurring at lower freq, high TV than healthy

33

what is anatomical dead space what % of total lung volume why is it called dead space

difference between minute ventilation and alveolar ventilation = air flow through AIRWAYS per minute BEFORE REACH ALVEOLAR 30% NO GAS EXCHANGE

34

how does a snorkel affect the anatomical dead space

LARGER ANATOMICAL DEAD SPACE

enlarges you have to breathe deeper and slower frequency because to get air down to alveoli must move air through tubing so total air intake has to be larger

35

define alveolar dead space

why called dead space

alveolus functioning perfectly well but sitting against an occluded pulmonary capillary NO GAS EXCHANGE (defective pulm capill)

36

what is significant about alveolar dead space in terms of efficiency of breathing and how that affects work in breathing such as in snorkeling

dead space decr efficiency of breathing

MORE WASTED VENTILATION (not contribute to gas exchange)

therefore, incr work in breath

(you have to breath deeper, slower freq to get air to alveoli thru tubing so total air intake has to be larger)

37

define physiologic dead space

physiologic dead space = anatomical dead space + alveolar dead space

38

what is anatomical dead space why is it called dead space

difference between minute ventilation and alveolar ventilation = air flow through airways per minute NO GAS EXCHANGE

39

how does a snorkel affect the anatomical dead space

enlarges

40

define alveolar dead space

why called dead space

alveolus functioning perfectly well but sitting against an occluded pulmonary capillary NO GAS EXCHANGE (defective pulm capill)

UNPERFUSED REGIONS OF LUNG

41

what is significant about alveolar dead space in terms of efficiency of breathing

dead space decr efficiency of breathing MORE WASTED VENTILATION

42

define physiologic dead space

physiologic dead space = anatomical dead space + alveolar dead space

43

can increases in dead space result in reduced alveolar ventilation?

TYPICALLY NOT changing alveolar ventilation manifests as V/Q mismatches unless snorkel too long, can't fill both long tubing and airway and alveoli

44

can increases in dead space result in reduced alveolar ventilation?

TYPICALLY NOT changing alveolar ventilation manifests as V/Q mismatches unless snorkel too long, can't fill both long tubing and airway and alveoli

45

Define (active breathing) Total lung capacity Vital Capacity Residual Volume

TLC = volume of lung with maximal inspiration VITAL CAPACITY = difference between TLC and Residual Volume Residual volume = minimal volume lung maintains with maximal EXPIRATION (~2L)

46

Define (quiet breathing) Tidal Volume Functional Residual Capacity

Tidal Volume = Difference between max and minimal volume of lung with quiet breathing FRC (~3 L) = volume of lung after quiet expiration = minimal volume of lung with quiet breathing

47

a

a

48

How to measure dynamics of airflow Procedure

1) Patient quietly breathing 2) Patient takes in max inspiration incr lung capacity 3) Patient then breathes out with max expiration 4) Measure rate of air flow 5) Lung returns to residual volume

49

Equation for rate of airflow

rate of air flow during expiration = FEV 1.0 / FVC

50

Define FEV 1.0 FVC

FEV 1.0 = volume of air flow in 1st second FVC = total amount of air moving after max expiration

51

how does pulmonary fibrosis affect compliance

Can't inflate lung fully, decr VC

Do not affect airway resistance (may even incr FEV1.0/FVC

Forces on lung to deflate towards intrinsic equilibrium position are greater with pulm fibrosis

 

52

Effect of bronchitis on RV, FRC, TLC, VC

incr FRC and incr RV due to air trapping

decr FEV1.0/FVC due to extra air trapped in lung with expiration

decr VC because airway resistance

53

What are situations where we increase proportion of anatomic dead space

1) breathe rapidly, small tidal volume (so tidal volume doesn't reach alveoli) = compliance problem

2) snorkeling (incr total conducting path for air)

54

Effect of decr compliance disease on elastic and resistance work

55

What is different about emphysema from other obstructive lung diseases?

unchanged or small incr (rather than decr) in vital capacity due to incr lung compliance so reach higher lung volumes