Pulmonary Function Testing (Selby)

Question 1

What are the five components of PFT?

Answer 1

1) Spirometry w flow volume loops
2) Lung volumes and capacities
3) Diffusing capacity of CO (DLCO)

4) Bronchodilator therapy - 12% or more increase in FEV1 or FVC and an absolute volume increase o 200ml or more

–> Positive=Asthma, Negative=COPD

5) Bronchoprovocation - methacholine challenge

Positive: more than 20% reduction in FEV1

Question 2

What is the purpose of pulmonary function testing (PFT)

Answer 2

• Evaluate sx’s and signs of lung disease (i.e., cough, dyspnea, wheezing, hyperinflation, etc.
• Assess progression of lung disease
• Monitor effectiveness of therapy
• Evaluate preoperative patients in selected situation
• Screen people at risk for pulmonary disease such as smokers or people with occupational exposure
• Monitor for potentially toxic effects of certain drugs/chemicals

Question 3

Indications for PFT

Answer 3

DOE

Cough

Asthma

Suspected bornchiectasis or bronchiolitis

Suspected ILD

Suspected neuromuscular or chest wall disease

Question 4

Pulmonary function tests are not indicated in which patients; may be confusing when what is present?

Answer 4

Not indicated in pt’s without sx’s

May be misleading when non-pulmonary diseases that effect the pulmonary system are active (i.e., CHF); pt may appear to have pulmonary disease

Question 5

What are the 3 most important values measured during pulmonary function testing?

Answer 5

• FVC
• FEV₁
• FEV₁/FVC ratio

Question 6

What is the FEV₁/FVC ratio used to determine?

Answer 6

If pattern is obstructive, restrictive, or normal

Obstructive: < 0.70 of normal

Question 7

Which gas is used to assess the diffusion capacity of the lungs (DLCO)?

Answer 7

Carbon monoxide

Question 8

For obstructive disease, measurement of the RV and TLC can be used to demonstrate what?

Answer 8

Airway obstruction

Hyperinflation

Question 9

What value is needed to confirm true restriction and to better quantitate the degree of restriction in a restrictive lung disease?

Answer 9

TLC

Question 10

If the FEV₁/FVC ratio is either normal or increased this may indicate restrictive disease or normal study, how can the FVC value be used for further interpretation?

Answer 10

If the FVC is NOT less than the lower limit of normal = normal study

If FVC is less than the lower limit of normal = restrictive pattern

Question 11

What is the FVC like in an obstructive vs. restrictive pattern of disease?

Answer 11

Obstructive = decreased or normal

Restrictive = decreased

Question 12

What is the FEV₁ like in an obstructive vs. restricitve pattern of disease?

Answer 12

Obstructive = decreased

Restrictive = decreased or normal

Question 13

What is the TLC like in an obstructive vs. restricitve pattern of disease?

Answer 13

Obstructive = normal or increased

Restrictive = decreased

Question 14

Using the FEV₁ as % of predicted value for classifying the severity of an obstruction which value indicates mild, moderate, moderately severe, severe, and very severe?

Answer 14

• Mild = >70%
• Moderate = 60-69%
• Moderately severe = 50-59%
• Severe = 35-49%
• Very severe = <35%

Question 15

Air trapping will lead to an increase in which value of lung volume?

Answer 15

RV

Question 16

What are 4 extra-parenchymal causes of restrictive lung disease?

Answer 16

Obesity

Neuromuscular disease

Chest wall deformities

Large pleural effusions

Pneumothorax

Question 17

Which value can be used to distinguish between parenchymal vs. extraparenchymal causes of restrictive lung diseases?

Answer 17

Diffusing capacity of the lung

If below lower limit of normal after correcting for lung volumes = parenchymal disease likely

Question 18

DDX for obstructive lung diseases?

Answer 18

COPD: Chronic bronchitis, Emphysema

Asthma

Bronchiactasis

Bronchiolitis

Question 19

DDX for restrictive lung disease?

Answer 19

Chest Wall: Kyphosis, Scoliosis, Obesity, Chronic Pleural Effusion, Ankylosing Spnondylitis

Drugs

ILD

Neuromuscular: Amyotrophic lateral sclerosis (ALS) Guillain-Barr (GBS) Myasthenia Gravis (MG)

Question 20

What are the PFT characteristics of obstructive lung diseases?

Answer 20

FEV1 < 80%

FVC may be normal or reduced

FEV1/FVC < 0.70

Scooped/concave chair on loop

RV and TLC insreased

DLCO normal (asthma) or low (emphysema)

Asthma will have positive bronchodilator response

COPD and others will have negaive response

Question 21

If the FVC is less than normal, how can using the TLC and RV determine if there is a mixed pattern of obstructive/restrictive or if there is obstruction with air trapping?

Answer 21

If there is mixed pattern, the TLC will be decreased (<5 percentile of predicted) and the FEV1/FVC will also be low.

If air trapping is occurring then the TLC will be normal or elevated and the RV will be significantly increased

Question 22

What are the PFT characteristics of restrictive lung diseases?

Answer 22

FEV1 normal or mildly reduced

FVC < 80%

FEV1/FVC normal to > 0.70

Peaked or “witches hat” loop

RV and TLC decreased

DLCO low (e.g. ILD) or normal (NMSK)

Question 23

What is this flow-volume curve indicative of?

Answer 23

Vocal cord dysfunctions

Question 24

What is this flow-volume curve indicative of?

Answer 24

Asthma

Question 25

What do the curves of A-C represent?

Answer 25

A) Normal

B) Obstructive (i.e., asthma or COPD)

C) Restrictive