Lung function tests

Lung function tests are used for the following reasons:

• to diagnose respiratory impairment
• to quantify the severity of any impairment

There are four functional divisions of the respiratory system which can be analysed by pulmonary function tests:

• airways:
  • diseases of the airways may increase resistance to air flow
    
    
• alveoli:
  • diseases of the alveoli reduce gas exchange
    
    
• thoracic wall - the respiratory pump:
  • including the ribs, muscles of respiration, diaphragm
    
    
• neurological control system:
  • the depth and rate of breathing is determined in the brain