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Lung Function Tests

The Gold Coast Lung Function Laboratory has been in operation over the past 22 years, under the direction of Dr Michael Thompson, Respiratory and Sleep Physician. The laboratory equipment is the State of the Art Sensormedics VMax system. The laboratory provides a service to hospital inpatients and outside practitioners.

Two qualified Respiratory Scientists are available for tests from Monday to Friday by appointment.

Find out more about the lung function tests we conduct: 


Many common lung conditions can cause problems by narrowing the airways and causing shortness of breath. Narrow airways are hard to breathe through; the more the narrowing, the harder the breathing becomes. Spirometry allows us to measure this, as well as assessing the volume of air used in single breath.

This test involves you taking a full breath in and blowing out as hard and fast as you can for as long as possible into a calibrated spirometer. Measurements are made of how well your lungs can be emptied and filled with air. The test is performed while sitting down and takes 20 minutes to half an hour. It is usually done before and after breathing a bronchodilator spray such as Ventolin or Bryanyl to measure whether or not these agents are able to improve your breathing.

Prior to the test you will be asked to stop taking your reliever puffers for 6 hours or your controller puffers for 12 hours. If you think you cannot stop taking your puffers for this long please speak to our laboratory scientist beforehand.

Diffusing Capacity

This test is used to assess the ability of the lungs to diffuse inhaled oxygen from the lungs into the bloodstream and is the most common test performed after spirometry. It is often performed in conjunction with spirometry and lung volumes as part of a Complex Lung Function Test.

This test involves the inhalation of a test gas which is held for 10 seconds then blown out. A sample of the exhaled test gas is collected and analysed and compared to your predicted values. A change in concentration of the test gas reflects how well your lung tissue (parenchyma) is able to deliver oxygen to the red blood cells in the bloodstream. You may be asked to have a blood test if your diffusing capacity is impaired to exclude anaemia.

Lung Volumes

The lung volume test tells us how much air is left behind which can help your doctor what condition you may have present in your lungs and how much is left behind when you breathe out.

The test uses the nitrogen washout technique and takes about 20 mins. You will be required to gently breathe in and out through a mouthpiece and the test is not uncomfortable. This test requires you to breathe in 100% oxygen, and then the nitrogen in the lungs is washed out and measured. Exhaled Nitrogen is used to determine lung volumes in this test since normal room air that you breathe contains higher concentrations of Nitrogen (78%) compared to Oxygen, which is only 21%. It is important that your lips remain tightly sealed around the mouthpiece to prevent contamination with room air during the test. The scientist is able to detect any leaks during the test.


This test measures the muscle strength of the lungs. The maximum inspiratory pressure (MIP) measures the strength of your muscles that are you use during the inspiration of air during normal and forced breathing in. The maximum expiratory pressure (MEP) measures the strength of the muscles that are used during normal and forced breathing out.

This test requires you to blow in as hard as you can and to breathe out as hard as you can. The pressure you make when you breathe like this tells us the strength of your chest muscles. This test is repeated a few times and can be tiring.

Mannitol Challenge Test

This is the most modern test of bronchial reactivity which is less prone to false negative results than other traditional bronchial challenge tests. Bronchial provocation tests are commonly performed to assist with the diagnosis and treatment of asthma.

Increasing doses of a simple sugar (mannitol) impregnated with a dehydrating agent are inhaled at specific intervals and are intended to mimic the effects of physical exercise on the airways. Dehydration of the airways in this way will trigger a cascade of physiological processes which cause the smooth muscle in the bronchial airways to contract, akin to the effects of asthma. Spirometric measurements are conducted after each dose inhalation to gauge airway constriction.

A positive response is suggestive of active airway inflammation and airway hyper-responsiveness that is consistent with a diagnosis of asthma.

Find out what you need to do in preparation for Lung Function Tests, or contact the labratory for more information.

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