PHYS: Ventilation and Lung Volumes

Question 1

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

Answer 1

ventilation

Question 2

What is the equation for flow?

Answer 2

Flow= Change in Pressure/Resistance to Flow

Question 3

What values cannot be measured by spirometry?

Answer 3

• Residual Volume
• Functional residual capacity
• Total Lung Capacity

Question 4

What is TLC?

Answer 4

Total Lung Capacity = VC + RV

around 6 to 7 L

Question 5

What is TV?

Answer 5

Tidal Volume= volume of a normal breath

around 500 mL

Question 6

What is FRC?

Answer 6

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

Question 7

What are 2 ways to measure FRC?

Answer 7

Helium Dilution
Body Plethysmograph (Boyle's Law Box)

Question 8

What is FVC?

Answer 8

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

Question 9

What is IRV?

Answer 9

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

Question 10

What is ERV?

Answer 10

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

Question 11

What is FEV1?

Answer 11

Forced expiratory volume in 1 second

Question 12

What is a normal value for FEV1?

Answer 12

80% of the FVC

Question 13

How can you use the FEV1/FVC ratio clinically?

Answer 13

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

Question 14

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

Answer 14

Less than .7

both numbers are lowered, because it is difficult to expire through a narrowed airway, but FEV1 is lowered more!

Question 15

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

Answer 15

.8 or higher

FVC is reduced due to reduced expansion causing problems getting air into the lungs

Question 16

List 3 examples of an obstructive lung disease.

Answer 16

Asthma
Emphysema
Chronic Bronchitis

Question 17

List 2 examples of a restrictive lung disease.

Answer 17

Obestiy

Pulmonary Fibrosis

Question 18

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

Answer 18

Anatomic dead space ~ 150 mL

Question 19

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

Answer 19

Alveolar dead space= volume of non-perfused alveoli

Question 20

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

Answer 20

physiologic dead space

Question 21

What is the equation for minute ventilation?

Answer 21

Vmv= TV X f

minute ventilation = tidal volume X respiratory rate

Question 22

What is the difference between minute ventilation and alveolar ventilation?

Answer 22

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

Question 23

What is the equation for alveolar ventilation?

Answer 23

Valv= (TV - Dead Space) X f

Question 24

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

Answer 24

Dead space ventilation decreases as a percentage of minute volume

Question 25

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

Answer 25

Increasing the depth of breathing!

Question 26

What is atmospheric pressure in mmHg?

Answer 26

760

Question 27

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

Answer 27

the pressure difference from the alveoli to the mouth

Question 28

What is transpulmonary (transmural) pressure?

Answer 28

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

Question 29

How do we estimate the intrapleural pressure?

Answer 29

Inserting a balloon catheter into the esophagus for an estimate

Question 30

List the muscles that aid in inspiration.

Answer 30

``` Diaphragm External intercostals accessory muscles (scalene, SCM) ```

Question 31

List the muscles involved in expiration.

Answer 31

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

Question 32

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

Answer 32

Mid-inspiration

Question 33

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

Answer 33

End of inspiration

Question 34

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

Answer 34

Mid-expiration

Question 35

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

Answer 35

End of expiration

Question 36

How do you treat a pneumothorax?

Answer 36

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

Question 37

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

Answer 37

compliance

Question 38

Compliance is the inverse of what value?

Answer 38

elastance

Question 39

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

Answer 39

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

Question 40

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

Answer 40

hysteresis

Question 41

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

Answer 41

surface tension

Question 42

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

Answer 42

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

Question 43

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

Answer 43

lower

Question 44

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

Answer 44

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

Question 45

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

Answer 45

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

Question 46

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

Answer 46

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)

Question 47

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

Answer 47

inability to expire at a normal rate

Question 48

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

Answer 48

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

Question 49

What are the two major factors that determine lung compliance?

Answer 49

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

Question 50

What is surfactant?

Answer 50

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

Question 51

What stimulates surfactant production?

Answer 51

deep breaths

Question 52

What is the major role of surfactant?

Answer 52

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

Question 53

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

Answer 53

decreases compliance

Question 54

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

Answer 54

small (decreased radius, increased pressure)

Question 55

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

Answer 55

radius of airway!

Question 56

List the 4 factors affecting airway resistance.

Answer 56

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