PHYS: Ventilation and Lung Volumes Flashcards Preview

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Flashcards in PHYS: Ventilation and Lung Volumes Deck (56):
1

What is the term for the volume of air moving into or out of the lungs in a given time?

ventilation

2

What is the equation for flow?

Flow= Change in Pressure/Resistance to Flow

3

What values cannot be measured by spirometry?

-Residual Volume
-Functional residual capacity
-Total Lung Capacity

4

What is TLC?

Total Lung Capacity = VC + RV
around 6 to 7 L

5

What is TV?

Tidal Volume= volume of a normal breath
around 500 mL

6

What is FRC?

Functional Residual Capacity= ERV + RV
(volume of air int he lungs after a normal expiration)
around 2.5 L

7

What are 2 ways to measure FRC?

Helium Dilution
Body Plethysmograph (Boyle's Law Box)

8

What is FVC?

Forced Vital Capacity= TV + IRV + ERV
(volume of air exhaled during a forceful expiration)
around 5 L

9

What is IRV?

Inspiratory Reserve Volume is the additional amount that can enter during forced inspiration
around 3L

10

What is ERV?

Expiratory Reserve Volume is the difference between tidal end volume and forceful expiration end volume
around 1L

11

What is FEV1?

Forced expiratory volume in 1 second

12

What is a normal value for FEV1?

80% of the FVC

13

How can you use the FEV1/FVC ratio clinically?

To distinguish whether your patient has an obstructive or restrictive lung disease

14

What is the FEV1/FVC ratio for an obstructive lung disease?

Less than .7
(both numbers are lowered, because it is difficult to expire through a narrowed airway, but FEV1 is lowered more!)

15

What is the FEV1/FVC ratio for an restrictive lung disease?

.8 or higher
(FVC is reduced due to reduced expansion causing problems getting air into the lungs)

16

List 3 examples of an obstructive lung disease.

Asthma
Emphysema
Chronic Bronchitis

17

List 2 examples of a restrictive lung disease.

Obestiy
Pulmonary Fibrosis

18

What is the volume of the conducting airways not available for gas exchange? What is this called?

Anatomic dead space ~ 150 mL

19

What is the volume of alveolar space not available for gas exchange due to limitations in blood supply (e.g. embolis)?

Alveolar dead space= volume of non-perfused alveoli

20

What is the sum of anatomic dead space and alveolar dead space?

physiologic dead space

21

What is the equation for minute ventilation?

Vmv= TV X f

(minute ventilation = tidal volume X respiratory rate)

22

What is the difference between minute ventilation and alveolar ventilation?

Minute ventilation does not account for the fact that no gas exchange occurs in the dead space

23

What is the equation for alveolar ventilation?

Valv= (TV - Dead Space) X f

24

Why is their a greater ratio of exercise/rest for alveolar ventilation versus minute ventilation?

Dead space ventilation decreases as a percentage of minute volume

25

Which is more effective for alveolar ventilation: increasing depth of breath or increasing breathing rate?

Increasing the depth of breathing!

26

What is atmospheric pressure in mmHg?

760

27

What is the driving force for flow into and out of the lungs?

the pressure difference from the alveoli to the mouth

28

What is transpulmonary (transmural) pressure?

the difference between the alveolar pressure and the intrapleural pressure (outside the lungs)

29

How do we estimate the intrapleural pressure?

Inserting a balloon catheter into the esophagus for an estimate

30

List the muscles that aid in inspiration.

Diaphragm
External intercostals
accessory muscles (scalene, SCM)

31

List the muscles involved in expiration.

None normally (passive), but during exercise:
Internal intercostals
Abdominal muscles

32

When is the alveolar pressure most negative in the breathing cycle?

Mid-inspiration

33

When is the intrapleural pressure most negative in the breathing cycle?

End of inspiration

34

When is the alveolar pressure most positive in the breathing cycle?

Mid-expiration

35

When is the intrapleural pressure most positive in the breathing cycle?

End of expiration

36

How do you treat a pneumothorax?

intrapleural pressure equalizes with atmosphere, so you place a chest tube, hook it up to suction, and create a negative pressure

37

What is another word for the "stretchability" of the lung?

compliance

38

Compliance is the inverse of what value?

elastance

39

How do you calculate compliance from a pressure-volume curve?

it is the slope of the pressure volume curve, or:
change in volume/change in pressure

40

What word is used to describe the pressure-volume curve of the lung?

hysteresis

41

What causes the hysteresis seen in the pressure-volume curve of the lung?

surface tension

42

Decreased compliance is caused by diseases like what? What do they do to the lungs?

Restrictive diseases: fibrosis, edema
make the lungs stiffer where you cannot get air IN

43

Do people with decreased compliance have a higher or lower FRC?

lower

44

Increased compliance is caused by diseases like what? What do they do to the lungs?

Obstructive ventilatory defects: emphysema
Makes the lungs more stretchy and prone to collapse where you cannot get air OUT

45

Do people with increased compliance have a higher or lower FRC?

Higher (must breathe in larger volumes to fill lungs--barrel-shaped chests)

46

True or false: intrapleural pressure is always a negative value.

FALSE: forced expiration will change intrapleural pressure to a positive value which can be problematic (cause collapsed airways) for people with COPD or people with reduced elastic recoil (increased compliance)

47

A flow-volume loop of an obstructive ventilatory defect will show what?

inability to expire at a normal rate

48

A flow-volume loop of a restrictive ventilatory defect will show what?

reduced volume of air in lungs (can't get as much in

49

What are the two major factors that determine lung compliance?

1) Tissue properties (1/3 is dependent on collagen, elastin, and interdependence)
2) Surface tension (molecular attractive force between lipid molecules

50

What is surfactant?

a mixture of phospholipids (ex. DPPC), cholesterol, and proteins produces by type II pneumocytes and stored in lamellar bodies

51

What stimulates surfactant production?

deep breaths

52

What is the major role of surfactant?

Increases lung compliance
Reduces the work needed to expand lungs
Reduces the tendency for pulmonary edema

53

In neonatal RDS, the lack of surfactant does what to the lung compliance?

decreases compliance

54

Which has a greater pressure, a large or small alveoli?

small (decreased radius, increased pressure)

55

What is the most important factor in resistance of airflow through the lungs?

radius of airway!

56

List the 4 factors affecting airway resistance.

1) Lateral traction (elastic tissue holding airway open from outside)
2) Lung volume (means increased airway diameter)
3) Relaxation/contraction of bronchial smooth muscle
4) Density and viscosity of inhaled gas