Pulmonary Function Tests (PFT)

Question 1

Three main PFT’s

Answer 1

• Spirometry = to identify obstruction
• Lung volume Determination = to identify restriction
• Diffusion Capacity Measurement = to identify a diffusion defect

Question 2

What is normal PFT measurement relative to predicted values?

Answer 2

values between 80% and 120 %

Question 3

What are signs of obstruction on spirometry?

Answer 3

Reduced ratio of FEV1 to FVC (normal is 70%)

-“Scooping” of Flow volume loop

Question 4

FEV1 severity guidelines

Answer 4

mild = 60 -80%
moderate = 40 - 60%
severe =

Question 5

Reversibility guidelines

Answer 5

-FEV1 increase by 200 cc and 12% with bronchodilator

Question 6

Hyper-reactivity challenge

• What do you give them?
• Decrease by how much?

Answer 6

• methacholine

- FEV1 decrease by 20 %

Question 7

Small airway obstruction

Answer 7

• gradually decreasing airflow
• obstruction worsens as lung volume decreases
• –due to decreased tethering of bronchioles at low volumes

Question 8

Upper airway obstruction

Answer 8

• airflow is fixed

- –even at high lung volumes since large airways don’t depend upon tethering to remain open

Question 9

Where is the obstruction located if it affects the inspiratory limb?

Answer 9

-extra thoracic

Question 10

Where is the obstruction located if it affects the expiratory limb?

Answer 10

-Intra thoracic

Question 11

What tests are used to measure lung volumes?

Answer 11

Helium Dilution

Body Box Plethysmography

Question 12

Restrictive Lung Disease guidelines

Answer 12

-less than 80% of predicted

Question 13

Interstitial Lung Disease mnemonic

Answer 13

• Sarcoid
• Hypersensitivity Pneumonitis
• Idiopathic Pulmonary Fibrosis
• Tuberculosis
• Fungal
• Aspiration/Asbestosis
• Connective Tissue Diseases/ (Cancer)
• Eosinophilic granuloma
• Drugs

Question 14

Three categorical causes of Restrictive Lung Diseases

Answer 14

• Interstitial lung Disease
• Chest wall Disease
• Neuromuscular Disease

Question 15

What is the method of measure diffusion capacity?

Answer 15

Measuring Inhaled vs. Exhaled Carbon Monoxide

Question 16

What is the normal diffusion capacity?

Answer 16

25 mL/min/mmHg

• correct for anemia/low Hbg
• correct for patient’s lung volume

Question 17

Reasons for decreased diffusion capacity

Answer 17

Both obstructive and restrictive diseases

• Loss of alveoli (emphysema or Interstitial lung disease)
• Loss of capillaries
• Anemia

Question 18

Reasons for increased diffusion capacity

Answer 18

• Alveolar hemorrhage
• CHF
• Polycythemia