Last reviewed 07/2021

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