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Spirometry involves blowing out as fast as possible into a special piece of equipment called a Spirometer.

The test will be performed with you seated and your nose may be sealed with a noseclip. You will be asked to breathe normally into a mouthpiece and instructed to take a deep breathe in and then to blow out as fast as possible and try and keep blowing until your lungs are empty. This will be performed a minimum of three times, but you will be given adequate rest between each blow.

This test measures the volumes and speed of the air you can blow out from your lungs and will give the doctor an indication of how clear the airways are in your lungs. For example the airways may be narrower in conditions such as COPD (Chronic Obstructive Pulmonary Disease) or Asthma.

Spirometry may then be repeated after you have been given an inhaler or nebuliser. This will be to see if there is any improvement in your airways as a result of taking this medication.

When the maximal blow is performed together with a maximal suck this test is sometimes referred to as a 'Flow Volume Loop'.

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