Pulmonary Function

Question 1

What are the three main components of PFTs?

Answer 1

spirometry (how air exits and enters) lung volume diffusion capacity

Question 2

What are three ways of determining lung volumes?

Answer 2

1. helium dilution 2. nitrogen washout 3. body plethysmography

Question 3

How does helium dilution lung volume testing work?

Answer 3

Helium is inhaled and allowed to equilibrate. decrease in concentration is compared to previous concentration and volume, to calculate for new volume (of the lung)

Question 4

What equation is used to determine lung volume during body plethysmography?

Answer 4

boyles law P1 V1 = P2V2

Question 5

What would be characteristic of lung volumes in obstructive diseases?

Answer 5

hyperinflation

Question 6

Why does emphysema increase lung volumes?

Answer 6

loss of elastic recoil elevates RV, while airway collapse traps gas on exhalation

Question 7

Why does chronic bronchitis and asthma cause increased lung volumes?

Answer 7

Increased airway resistance traps air and causes hyperinflation

Question 8

What is responsible for the decrease in lung volumes in restrictive diseases?

Answer 8

INcreased elastic recoil (decreased compliance) decreases lung volume

Question 9

What is true of lung volumes in restrictive diseases?

Answer 9

they are decreased

Question 10

What is the volume that patients are asked to inhale on spirometry?

Answer 10

total lung capacity

Question 11

What is the volume that patients are asked to exhale to during spirometry?

Answer 11

RV

Question 12

What value is generated from the difference between inhaled volumes and exhaled volumes in spirometry?

Answer 12

the forced vital capacity = TLC - RV

Question 13

In normal individuals, how long does it take to reach FVC in spirometry?

Answer 13

~ 4 seconds

Question 14

What is a normal FEV1?

Answer 14

~75%

Question 15

In health, what is the ratio of FEV1 to FVC?

Answer 15

75% or 0.75

Question 16

As you age, what happens to FEV1/FVC?

Answer 16

the ratio drops

Question 17

When there is expiratory obstruction, what happens to FEV 1 and FVC?

Answer 17

FEV1 drops more than FVC, lowering FEV1/FVC

Question 18

Why does FEV1 drop in obstructive lung disease?

Answer 18

FEV1 drops because of decreased lung elastic recoil pressure or increased airflow resistance

Question 19

What accounts for the fact that FEV1 tends to drop more than FVC in obstructive disease?

Answer 19

patients compensate by exhaling longer to reach the same FVC

Question 20

What do restrictive defects do to FEV1 and FVC?

Answer 20

drop both of them

Question 21

Although FEV1 and FVC drop in restrictive disease, what happens to flow?

Answer 21

Flow at any given point will be higher (isovolume flow)

Question 22

Why is isovolume flow higher than normal in restrictive defects?

Answer 22

they may be higher than normal because elastic recoil pressure is higher and airway resistance is lower than normal i.e. exhalation is shorter than normal and FEV1/FVC may increase

Question 23

Although FEV1 and FVC both drop in restrictive diseases, FEV1/FVC can increase. Why?

Answer 23

exhalation is shorter and isovolume flow is higher, so the ratio of FEV1 to FVC is higher

Question 24

Can you tell asthma and COPD apart on spirometry alone?

Answer 24

no, unless you compare pre and post bronchodilator and see improvements in FEV1 and/or FVC

Question 25

What type of conditions elevate DLCO?

Answer 25

DLCO is elevated in disorders resulting in increased hemoglobin in areas of intact ventilation (e.g.: alveolar hemorrhage and polycythemia)

Question 26

What effect does alveolar hemorrhage have on DLCO?

Answer 26

increases it

Question 27

What effect does polycythemia (from chronic hypoxemia, for example) have on DLCO?

Answer 27

increases it

Question 28

What type of conditions decrease DLCO?

Answer 28

decreased when ventilation does not match perfusion (i.e. low V/Q) or when there is loss of blood (anemia) or functional blood vessels (pulmonary embolism, emphysema, interstitial lung disease)

Question 29

What does a low V/Q do to DLCO?

Answer 29

Decreases it

Question 30

What does anemia do to DLCO?

Answer 30

decreases it

Question 31

What does pulmonary embolism do to DLCO?

Answer 31

Decreases it

Question 32

What does emphysema do to DLCO?

Answer 32

decreases it

Question 33

What does ILD do to DLCO?

Answer 33

decreases it

Question 34

How do you calculate inspiratory capacity?

Answer 34

TLC - FRC

Question 35

How do you calculate the expiratory reserve volume?

Answer 35

FRC - RV

Question 36

how do you calculate theinspiratory reserve volume?

Answer 36

IC-TV

Question 37

Where is TLC found on the flow volume curve?

Answer 37

on the X axis, where you shift from inspiration to expiration

Question 38

What does the width of the flow volume curve correspond to?

Answer 38

the FVC

Question 39

What is suggested by a flattened inspiratory loop on the flow volume curve?

Answer 39

Flattening of the inspiratory loop suggests inadequate strength, effort or technique during the forced inhalation maneuver, or upper airway obstruction (eg, vocal cord dysfunction, epiglottitis, laryngeal edema, and laryngeal malignancy).

Question 40

Which side of the flow volume loop is asymmetric: expiratory or inspiratory?

Answer 40

expiratory

Question 41

Why is the expiratory part of the flow volume loop asymmetric?

Answer 41

The normal expiratory loop is asymmetric because higher expiratory flows are generated at larger lung volumes. This is because at higher lung volumes lung elastic recoil pressure (Pel) is greater (like stretching a sponge or rubber band) and airway resistance is lower as the inflated lung “pulls” airways open via the tethering effects of alveoli.

Question 42

What are the two determinants of maximal expiratory flow?

Answer 42

flow = Pel/Rus Where Pel: elastic recoil pressure Rus: resistance distal to the equal pressure point

Question 43

Why is Ppl (pleural pressure) not part of the equation for maximum flow in the flow volume loop?

Answer 43

Ppl, which is related to effort, is not a part of this equation; thus the concept of effort independence of maximal airflow: expiratory flow is independent of effort

Question 44

How are expiratory flow rates related to lung volume?

Answer 44

at higher lung volumes, expiratory flow rates are higher

Question 45

what does the obstructive defect look like on the time volume curve?

Answer 45

A ramp

Question 46

What does restrictive disease look like on the volume time curve?

Answer 46

a rectangle

Question 47

Expiratory airflow is decreased most by what combination of pathophysiologic conditions? a) low Pel and high Raw b) high Pel and high Raw c) low Pel and low Raw d) high Pel and low Raw

Answer 47

**a) low Pel and high Raw** b) high Pel and high Raw c) low Pel and low Raw d) high Pel and low Raw

Question 48

Emphysema is best characterized by: a) high FEV₁/FVC b) hyperinflation with low DLCO c) high Pel and low Raw d) fixed inspiratory and expiratory airflow obstruction

Answer 48

a) high FEV₁/FVC **b) hyperinflation with low DLCO** c) high Pel and low Raw d) fixed inspiratory and expiratory airflow obstruction

Question 49

. Isovolume airflow is high in: a) asthma b) vocal cord paralysis c) pulmonary fibrosis d) pulmonary embolism

Answer 49

a) asthma b) vocal cord paralysis **c) pulmonary fibrosis - restrictive disease** d) pulmonary embolism

Question 50

Which of the following test results suggests asthma? 1. Low FEV₁/FVC that normalizes after albuterol 2. Low FEV₁/FVC with low diffusing capacity 3. Normal FEV₁/FVC after an irritant challenge 4. Normal FEV₁/FVC with low diffusing capacity

Answer 50

1. **Low FEV₁/FVC that normalizes after albuterol** 2. Low FEV₁/FVC with low diffusing capacity 3. Normal FEV₁/FVC after an irritant challenge 4. Normal FEV₁/FVC with low diffusing capacity

Question 51

Flattening of the inspiratory loop suggests: a) asthma b) vocal cord paralysis c) pulmonary fibrosis d) pulmonary embolism

Answer 51

a) asthma **b) vocal cord paralysis** c) pulmonary fibrosis d) pulmonary embolism