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► Med - Pathology > Pulmonary Function Tests > Flashcards

Pulmonary Function Tests Flashcards

1
Q

What is the main test used to identify obstruction?

A

Spirometry

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2
Q

What is the main test used to identify restriction?

A

Lung Volume Determination

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3
Q

What is the main test used to identify diffusion defects?

A

Diffusion Capacity Measurement

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4
Q

What is the normal range of PFT values determined by?

A

Within 80-120% of the predicted values

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5
Q

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

A

Pre and post bronchodilator treatment

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6
Q

What happens to the spirometry measurements in obstruction?

A

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

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7
Q

How is spirometry conducted?

A

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

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8
Q

What is the main value that identifies obstruction?

A

Reduced FEV1/FVC Ratio below 0.7

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9
Q

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

A

Scooping will occur

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10
Q

When is airflow on expiration the highest?

A

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

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11
Q

What is the normal range of FEV1?

A

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

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12
Q

What is reversibility of obstruction with a bronchodilator indicative of?

A

Response to a bronchodilator is indicative of asthma

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13
Q

What is a methacholine challenge?

A

Used to determine hyper reactivity in cases of asthma

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14
Q

What defines hyper reactivity?

A

FEV1 􏰄decreases by 20% in response to methacholine

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15
Q

What are the common obstructive diseases?

A

􏰀 Asthma
􏰀 COPD
􏰀 Bronchiectasis

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16
Q

Where does the obstruction occur the majority of the time?

A

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

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17
Q

What is seen in small airway obstruction (lower)?

A

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

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18
Q

What is seen in large airway obstruction (upper)?

A

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

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19
Q

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

A

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

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20
Q

What are the features of Fixed upper airway obstruction?

A
  • 􏰀 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
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21
Q

What are the features of Variable upper airway obstruction?

A

There are two types:

  • 􏰀 Inspiratory limb affected = Extra-thoracic obstruction
  • Expiratory limb affected = Intra-thoracic obstruction
22
Q

How does inspiratory variable upper airway obstruction occur?

A

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

23
Q

How does expiratory variable upper airway obstruction occur?

A

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

24
Q

What can cause an intrathoracic UAO?

A

Tracheomalacia

25
Q

What can cause an extra thoracic UAO?

A

Vocal Cord Dysfunction

26
Q

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

A

-􏰀 Helium Dilution

􏰀- Body Box Plethysmography

27
Q

What happens to lung volume with increased elastic recoil?

A

It will decrease

28
Q

What is RV?

A

The volume of gas trapped due to airway closure

29
Q

What is FRC determined by?

A 
The balance between Elastic Recoil of the Lung (in) vs
Chest Wall (out)
30
Q

What is the main value that identifies restriction?

A

Reduced Total Lung Capacity below 80% of predicted value

31
Q

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

A
  • Interstitial Lung Disease
  • Chest Wall Disease
  • Neuromuscular Disease
32
Q

How does interstitial lung disease cause restriction?

A

Increases the elastic recoil of the lungs

33
Q

How does chest wall disease cause restriction?

A

Decreases the elastic recoil of the chest wall

34
Q

How does neuromuscular disease cause restriction?

A

Decreases TLC and Increases RV

35
Q

What are examples of interstitial lung diseases?

A

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

36
Q

What are examples of chest wall diseases?

A
  • Obesity

- Kyphoscoliosis

37
Q

What are examples of neuromuscular diseases?

A
  • ALS

- Muscular Dystrophy

38
Q

How is neuromuscular disease proven in relation to PFTs?

A

-􏰀 Negative Inspiratory Force (NIF)

􏰀- Positive Expiratory Force (PEF)

39
Q

What is the most likely cause of restrictive lung disease?

A

Interstitial lung diseases

40
Q

What is the diffusion capacity?

A

Alveolar-Capillary Surface Area available for gas exchange

41
Q

How is the diffusion capacity determined?

A

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
Q

What is the corrected DLCO?

A

It is corrected using the patient’s Hb

DLCO x (15/Pt Hb) = Corrected DLCO

43
Q

What is the DL/VA?

A

It corrects for the patient’s lung volume

DL/VA = DLCO corrected / Alveolar Volume

44
Q

What is a reduced DLCO indicative of?

A
  • 􏰀 Loss of alveoli -􏰀 Both Emphysema and ILD 􏰀
  • Loss of capillaries - Pulmonary Hypertension 􏰀
  • Anemia
45
Q

What is an increased DLCO indicative of?

A

-􏰀 Alveolar Hemorrhage 􏰀
- CHF
􏰀- Polycythemia

46
Q

When is the DLCO expected to be low?

A

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
Q

When is pulmonary HTN suspected?

A

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

48
Q

Reduced 􏰄FEV1/FVC Indicates

A

Asthma
COPD
Bronchiectasis

49
Q

Reduced TLC Indicates

A

Interstitial Disease
Chest Wall Disease
Neuromuscular Disease

50
Q

Decreased DLCO Indicates

A

Associated with COPD and/or ILD

Isolated indicates Primary Pulmonary HTN

► Med - Pathology (203 decks)

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