Spirometry (measuring the lung capacity) is the most important test to diagnose and monitor COPD.

COPD causes narrowing of the bronchial tubes (or airways), resulting in shortness of breath. The greater the narrowing, the more difficult breathing becomes. Spirometry is a test which measures exactly how much the bronchial tubes have narrowed.  The spirometer measures the speed your lungs can be filled and emptied of air, giving an indication of how well your lungs are performing. This enables your doctor to make decisions about your lung condition and to plan the best treatment for you. Further spirometry tests later on can help decide whether treatments should be continued, changed, or are no longer needed.

What happens?

Having a spirometry test is straightforward. It may occasionally be tiring and make you feel a bit puffed, but usually it is not uncomfortable. The test involves taking a full breath in and blowing out with your best effort into a tube attached to the spirometer machine. Various measurements will indicate how your lungs are working. The test is performed whilst seated and usually takes 10 to 20 minutes. It is sometimes carried out before and after inhaling a reliever drug such as Ventolin or Bricanyl to measure the effect of these drugs. In this case, your doctor may ask you not to take your usual reliever medication for a few hours prior to the test.

To ensure the test is done accurately, you will be asked to:
  • Breathe in as deeply as you can
  • Seal your lips around the mouthpiece
  • Blow out as hard and fast as you can, and keep going as long as possible.

This test will be repeated three times.

Don't forget to breathe is a guide for patients with Chronic Obstructive Pulmonary Disease (COPD). Download your free copy.

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