Lung function

How to get an appointment

A doctor or consultant from our hospitals will refer you for lung function tests.

Changing or cancelling your appointment

Pathway coordinator: 020 7188 7188, extension 55676

If there is no answer, please call reception:

If you're running late for your appointment, please let us know. We may not be able to see you if you're more than 15 minutes late.

Before your appointment

Please tell us if you have:

  • a current chest infection
  • coughing up blood within 3 days of appointment
  • a positive coronavirus (COVID-19) test within 3 weeks of appointment
  • a heart attack within 6 weeks of appointment
  • a collapsed lung or blood clot in the lung within 6 weeks of appointment
  • eye, abdominal or chest surgery within 6 weeks of appointment
  • chest, stomach or brain aneurysm within 6 weeks of appointment

If you have any of these, we may need to rearrange your appointment.

Please do not:

  • exercise 30 minutes before your test
  • eat a large meal 2 hours before your test
  • drink alcohol 4 hours before your test
  • smoke 24 hours before your test
  • wear tight fitting clothing which can restrict your chest or abdomen

For an exercise test, mannitol challenge or hyperventilation test, please arrive 30 minutes before your test to do a COVID-19 lateral flow test.


If you use an inhaler, please do not use:

  • Salbutamol/Ventolin and Terbutaline/Bricanyl for 6 hours before your appointment
  • Spiriva for 24 hours before your appointment
  • long-acting bronchodilators (such as Serevent, Symbicort, Seretide or Flutiform) for at least 24 hours before your appointment

Exercise test and 6-minute walk test

Please wear comfortable clothes and shoes. Please do not wear nail polish on the day of testing.

Skin prick test

For 3 full days before your test, please do not use antihistamine tablets and nasal sprays such as:

  • Zyrtec
  • Telfast
  • Claratyne

Manitol challenge

Before your mannitol challenge test, please stop taking:

  • inhaled non-steroidal anti-inflammatory agents, such as sodium cromoglycate, nedocromil sodium, 6 to 8 hours before
  • short-acting beta 2 agonists, such as salbutamol, terbutaline, 8 hours before
  • inhaled corticosteroids, such as beclomethasone, budesonide, 12 hours before
  • ipratropium bromide, 12 hours before
  • inhaled corticosteroids plus long-acting beta agonists, such as fluticasone and salmeterol; budesonide and formoterol, 24 hours before
  • long acting beta 2 agonists, such as salmeterol, eformoterol, 24 hours before
  • theophylline, 24 hours before
  • tiotropium bromide, 3 days before
  • antihistamine tablets and nasal sprays, such as cetirizine, fexofenadine and lorotadine, 3 days before
  • leukotriene-receptor antagonists, such as montelukast, 4 days before

During your appointment

We'll carry out lung function or breathing tests to understand how well:

  • you move air in and out of your lungs
  • oxygen enters your body

Depending on which tests you need, it will take 30 minutes to 1 hour.

Common lung function tests

We'll provide more information about the test you are having at your appointment.

The NHS website has information about spirometry.

A gas diffusion test measures how well you're able to move oxygen from your lungs into your blood supply. During this test you'll breathe in some gas and then breathe into a machine through a mouthpiece.

A static lung volumes test measures how much air you have left in your lungs after blowing all the way out. There are 2 different methods:

  • helium dilution involves you breathing a gas mixture (helium and oxygen), you'll breathe normally into a mouthpiece connected to a machine for about 5 minutes.
  • body plethysmography involves you sitting in a booth similar to a phone box, the door will be closed and you'll be attached to a mouthpiece. You’ll place your hand on your cheeks and breathe normally. At various stages during the test a shutter will briefly block the mouthpiece. Pressure measurements will be taken as you continue to breathe normally against the shutter.

Mannitol challenge tests if you have over-sensitive airways. Mannitol is a natural sugar. You'll breathe in a powder form of Mannitol in increasing doses from an inhaler. You'll then perform a breathing test 1 minute after each dose until a change is observed or the test is completed. You may experience increased coughing, wheeziness and breathlessness during this test. An inhaler can be given at the end to relieve any symptoms.

The 6-minute walking test involves you walking for 6 minutes up and down a corridor. Your oxygen saturation levels and heart rate are monitored by a finger probe. During the test you can rest.

The skin prick allergy test checks if you're allergic to airborne allergens, such as grass pollen and animal hair.

The fitness to fly test checks if you need oxygen when flying on an aeroplane. You'll breathe nitrogen gas for 20 minutes while we monitor your oxygen saturation levels.

The exercise bike test (CPET) measures your heart and lungs during exercise. During the test you'll sit on an exercise bike with ECG electrodes attached to your chest to monitor your heart. You'll have:

  • a facemask attached to monitor your breathing
  • a blood pressure cuff placed around your arm
  • a finger probe to monitor oxygen saturation levels.

You'll cycle at a low resistance which will gradually increase until you:

  • no longer feel that you can cycle, or
  • you're unable to turn the pedals at a specific rate

There'll be a recovery period to see how long it takes for your heart rate and breathing to return to pre-exercise levels.

After your appointment

The results of your tests will be sent to the health professional at our hospital who asked for them. They'll discuss the results with you during your appointment. They'll also send a copy of your results and report to your GP.

You should have a follow-up appointment with a doctor or consultant at our hospitals.

Contact us

For more information, please contact us.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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