What is Spirometry?

Spirometry is a type of lung function test, which we can carry out at Sloane Street Surgery. A spirometer is a mouthpiece connected to a special machine. By breathing into the mouthpiece, as we instruct you, the machine can measure:

  1. the amount of air you can breathe out in one second (forced expiratory volume or FEV1)
  2. the amount of air you can breath out in one forceful breath (forced vital capacity or FVC)

These measurements are then compared with a normal result for someone of your age, height and sex.


What does it involve?

We usually start by measuring your height and weight. Then we will ask you to breathe in fully, seal your lips around the mouthpiece, and breathe out as fast and far as you can. We may ask you to do this 2-3 times to check that the readings are the same each time. For your second type of breath, we will ask you to breathe in fully, seal your lips around the mouthpiece, and breathe out more slowly and far as you can. Again, we may ask you to repeat this.

If you already use inhalers, it is very helpful to bring them to the appointment but best to avoid using them before the test that day. A bronchodilator is an inhaler which dilates the airways, as its name describes. If you have a diagnosis of asthma already or we suspect you might have asthma, we may ask you to perform spirometry, then use a bronchodilator inhaler and wait 15 minutes before repeating spirometry to see if it helps to improve your lung function. This test is known as a bronchodilator reversibility test.

Some people can get a little light-headed when doing these tests but we can take our time.

As an aside, it is probably best to avoid spirometry during an acute infection. We also wouldn’t recommend spirometry if you have had a recent major health event which may be aggravated by forced expiration eg recent surgery, recent lung collapse, heart attack, stroke or perforated ear drum.


What can it tell us?

The two measurements (FEV1 and FVC) above can help us to work out if you have:

  1. Normal airways
  2. An obstructive airway disease: narrowing of the airways will make it hard to blow out most of your air in one second. The commonest types of obstructive airway disease are asthma and chronic obstructive pulmonary disease (COPD). COPD is sometimes known as ‘smokers lung’ by non-medics.
  3. A restrictive airway disease: lung tissue is damaged restricting the ability of the lungs to hold as much air (reduced capacity). The commonest type of restrictive airway disease is lung fibrosis.
  4. A combined obstructive/restrictive airway problem.

A lung function test, on the other hand, wouldn’t be as helpful in diagnosing a condition such as pneumonia or lung cancer.


Who is it for?

We particularly recommend spirometry if you have had a long-term cough or long-term breathlessness, are over 35 years old and smoke or you smoked for many years previously. Also, if you already have a certain lung condition, it can be used to monitor how well it is being controlled. Before major operations, spirometry also helps to give an idea of lung fitness beforehand.


What can we do to help you if we diagnose a lung function problem?

Depending on the abnormality found, we might want to perform further investigations such as more advanced lung function tests or imaging. We might be able to recommend medication to help with your lung condition there and then. Alternatively, we might recommend referring you to a respiratory physician.

If you have unexplained chest symptoms or feel you may benefit from a spirometry test, please book an appointment online here or call us on  0207 245 9333.

A 30-minute respiratory review with spirometry costs £250.

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