Lung Function Tests

Question 1

Briefly outline how to carry out a simple spirometry test

Answer 1

• Procedure is performed sitting in a chair or standing
• Nose clip worn during procedure
• Sterile mouthpiece used
• Patient breathes normally and then does a forced vital capacity

Question 2

Describe the measurement of forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1.0)

Answer 2

• Forced vital capacity is the total volume change after forced expiration
• FEV1 is the forced expiratory volume after 1 second
  In a healthy individual, - FEV1 = 80% of FVC

Question 3

State the axis of a flow volume loops

Answer 3

• Flow over volume

- Expiration above the x axis and inspiration below the x axis

Question 4

How are obstructive and restrictive patterns seen on spirometry

Answer 4

• In obstruction, it takes longer for lungs to empty
  
  • Creates a ‘scooped out’ flow volume graph
  • Decreased flow and volume
• In restriction, exhalation the same rate as healthy person - good flow
  
  • Reduced vital capacity
  • Lungs cannot expand as much - decreased inspiration and volume

Question 5

Give examples of obstructive and restrictive disorders

Answer 5

• Obstructive - COPD (emphysema, bronchitis), asthma, cystic fibrosis
• Restrictive - pulmonary fibrosis, sarcoidosis, scoliosis, neuromuscular disease (ALS, muscular dystrophy)

Question 6

Identify where to find peak expiratory flow rate (PEFR) and vital capacity on a flow volume loop

Answer 6

• PEFR located at the peak

- Vital capacity is the volume change on the x-axis

Question 7

Outline how FEV1 and FVC are affected in obstructive and restrictive disorder

Answer 7

• In obstructive disorder
  
  • FEV1 is reduced (cannot empty lungs)
  • FVC may be reduced
  • FEV1/FVC is reduced
• In restrictive disorder
  
  • FEV1 appropriate for lung volume
    
    • FVC reduced (lungs cannot expand as much)
  • FEV1/FVC is normal

Question 8

State whether obstructive and restrictive problems are seen on inspiration or expiration

Answer 8

• Obstructive - expiration

- Restrictive - inspiration

Question 9

State whether extra-thoracic and intra-thoracic abnormalities are seen on inspiration of expiration

Answer 9

• Intra-thoracic - expiration

- Extra-thoracic - inspiration