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Flashcards in Pulmonary Function Tests Deck (50):
1

What is the main test used to identify obstruction?

Spirometry

2

What is the main test used to identify restriction?

Lung Volume Determination

3

What is the main test used to identify diffusion defects?

Diffusion Capacity Measurement

4

What is the normal range of PFT values determined by?

Within 80-120% of the predicted values

5

What do pre- and post- values refer to in the PFT?

Pre and post bronchodilator treatment

6

What happens to the spirometry measurements in obstruction?

In Obstruction, less air is exhaled per unit time than expected for any given lung volume.

7

How is spirometry conducted?

After a full inspiration, patient blows out as forcefully as possible until all air has been exhaled.

8

What is the main value that identifies obstruction?

Reduced FEV1/FVC Ratio below 0.7

9

What will happen to the flow volume loop in cases of obstruction?

Scooping will occur

10

When is airflow on expiration the highest?

At High Lung Volumes. Both elastic recoil and airway diameter are maximal and thus flow is highest.

11

What is the normal range of FEV1?

At least 70%. Younger people should have an FEV1 closer to 80%.

12

What is reversibility of obstruction with a bronchodilator indicative of?

Response to a bronchodilator is indicative of asthma

13

What is a methacholine challenge?

Used to determine hyper reactivity in cases of asthma

14

What defines hyper reactivity?

FEV1 􏰄decreases by 20% in response to methacholine

15

What are the common obstructive diseases?

􏰀 Asthma
􏰀 COPD
􏰀 Bronchiectasis

16

Where does the obstruction occur the majority of the time?

99% of the time it will be found in the lower airways

17

What is seen in small airway obstruction (lower)?

-􏰀 obstruction worsens as lung volume decreases
􏰀due to decreased “tethering” of bronchioles
- gradually decreasing airflow

18

What is seen in large airway obstruction (upper)?

Obstruction even at high lung volumes since large airways don’t depend upon “tethering” to remain open

19

What will be the flow in upper airway obstruction at high lung volumes?

Flow is STILL reduced - in contrast to lower airway which will still have higher airflow at high lung volumes

20

What are the features of Fixed upper airway obstruction?

- 􏰀 Intra-thoracic pressure changes do NOT affect the
degree of obstruction
- Both Inspiratory and Expiratory limbs of the FVL are affected
- Obstruction may be located either intra- or extra-thoracic

21

What are the features of Variable upper airway obstruction?

There are two types:
- 􏰀 Inspiratory limb affected = Extra-thoracic obstruction
- Expiratory limb affected = Intra-thoracic obstruction

22

How does inspiratory variable upper airway obstruction occur?

Caused by extra thoracic obstruction as expiration is unaffected. Inspiration could be obstructed by trachea narrowing.

23

How does expiratory variable upper airway obstruction occur?

Caused by intrathoracic obstruction as inspiration is unaffected. Expiration is obstructed due to the pressure increase in the lung upon exhalation

24

What can cause an intrathoracic UAO?

Tracheomalacia

25

What can cause an extra thoracic UAO?

Vocal Cord Dysfunction

26

What are some techniques that can be used to measure lung volumes?

-􏰀 Helium Dilution
􏰀- Body Box Plethysmography

27

What happens to lung volume with increased elastic recoil?

It will decrease

28

What is RV?

The volume of gas trapped due to airway closure

29

What is FRC determined by?

The balance between Elastic Recoil of the Lung (in) vs
Chest Wall (out)

30

What is the main value that identifies restriction?

Reduced Total Lung Capacity below 80% of predicted value

31

What are the 3 categories of diseases that can cause restriction?

- Interstitial Lung Disease
- Chest Wall Disease
- Neuromuscular Disease

32

How does interstitial lung disease cause restriction?

Increases the elastic recoil of the lungs

33

How does chest wall disease cause restriction?

Decreases the elastic recoil of the chest wall

34

How does neuromuscular disease cause restriction?

Decreases TLC and Increases RV

35

What are examples of interstitial lung diseases?

􏰀- Sarcoid
􏰀- Hypersensitivity Pneumonitis
-􏰀 Idiopathic Pulmonary
- 􏰀Tuberculosis

36

What are examples of chest wall diseases?

- Obesity
- Kyphoscoliosis

37

What are examples of neuromuscular diseases?

- ALS
- Muscular Dystrophy

38

How is neuromuscular disease proven in relation to PFTs?

-􏰀 Negative Inspiratory Force (NIF)
􏰀- Positive Expiratory Force (PEF)

39

What is the most likely cause of restrictive lung disease?

Interstitial lung diseases

40

What is the diffusion capacity?

Alveolar-Capillary Surface Area available for gas exchange

41

How is the diffusion capacity determined?

Using CO to test. Carbon Monoxide easily diffuses across alveolar and capillary membranes.

DLCO = [CO]inhaled - [CO]exhaled

DLCO is used as a measure of the diffusion capacity - normal is 25

42

What is the corrected DLCO?

It is corrected using the patient's Hb

DLCO x (15/Pt Hb) = Corrected DLCO

43

What is the DL/VA?

It corrects for the patient's lung volume

DL/VA = DLCO corrected / Alveolar Volume

44

What is a reduced DLCO indicative of?

- 􏰀 Loss of alveoli -􏰀 Both Emphysema and ILD 􏰀
- Loss of capillaries - Pulmonary Hypertension 􏰀
- Anemia

45

What is an increased DLCO indicative of?

-􏰀 Alveolar Hemorrhage 􏰀
- CHF
􏰀- Polycythemia

46

When is the DLCO expected to be low?

Expected DLCO to be low in any disease with loss of either alveoli or capillaries. Both obstruction (emphysema) and restriction (pulmonary fibrosis) will have a low DLCO.

47

When is pulmonary HTN suspected?

Suspect Pulmonary Hypertension when DLCO is low but spirometry and lung volumes are normal

48

Reduced 􏰄FEV1/FVC Indicates

Asthma
COPD
Bronchiectasis

49

Reduced TLC Indicates

Interstitial Disease
Chest Wall Disease
Neuromuscular Disease

50

Decreased DLCO Indicates

Associated with COPD and/or ILD
Isolated indicates Primary Pulmonary HTN

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