Lung Function Testing

Respiratory function tests measure how well patients move air in and out of their lungs. Also, how well oxygen enters the body. The most common tests are spirometry, body plethysmography, diffusion studies and provocational tests.

Respiratory function tests allow your Doctor to

  • Compare your lung function with known standards
  • Measure the effect of chronic diseases eg asthma, chronic obstructive lung disease (COPD)
  • Identify changes in lung function including narrowing of the airways
  • Show if exposure to chemicals in your home or workplace may have affected your lung function
  • Determine your ability to tolerate surgery or certain medical procedures

To obtain the most accurate results

  • Do not smoke for at least 1 hour before testing
  • Do not eat a large meal or drink alcohol within 4 hours before the test
  • Do not wear tight clothing which makes it difficult for you to take a large breath
  • Ask your Doctor if there are any medications that you should not take on the day of your test

Spirometry

Spirometry is one of the most commonly ordered lung function tests. The study measures how much air you can breathe into your lungs and then blow quickly out of your lungs. The test is often repeated after inhaling a medication (bronchodilator) to see if this improves your breathing.

The scientist carrying out the study may ask you to repeat the test 2 or 3 times in order to get accurate results. This person will help you to carry out the test properly. Spirometry takes approximately 30 minutes to complete.

Plethysmography

This test is designed to measure you total lung capacity. You cannot empty out all the air from your lungs. The amount of air remaining after you breathe out can be measured. In this test, the patient sits in an enclosed plastic box that they can see through. The study takes approximately 15 minutes.

Diffusion Studies

This test is to measure how efficiently gasses move from the lungs into the blood stream. The time for this study is approximately 15 minutes.

Bronchial Challenge Testing

Used for diagnosis and management of asthma, to assess a person for suitability to SCUBA dive or employers may request the test for employees with a history of possible previous asthma.

  • Please tell the supervising scientist if you do not understand their instructions.
  • Please notify the laboratory if you have a cold or flu. These illnesses may temporarily affect your lung function and the staff may want to reschedule your study.
  • When booking the tests, please ask if any of your medications need to be stopped and for how long the medication should not be taken before the test.
  • The results from your tests will usually be sent to the referring Doctor within 3 working days.