Lung function laboratory

These are tests that show how much air you are able to breathe in and out and how fast you can blow out and breathe air back in. We will ask you to breathe in fully and then blow out as hard and as fast as you can for as long as possible, before quickly breathing back in.

This test measures how efficiently oxygen passes from your lungs into your blood. We will ask you to breathe in a harmless gas through a mouthpiece and then hold your breath for about 10 seconds before breathing the gas back out. The exhaled gas will then be analysed and compared to the gas you breathed in, and from this we can see how much oxygen you can transfer across your lungs.

This test tells us exactly how big your lungs are and gives more detailed results than spirometry. The test will involve sitting inside a glass cubicle and breathing in and out for about a minute, with a noseclip on. We will give you clear instructions throughout the test via a microphone.

This test looks at your oxygen levels during mild exercise. A clip will be attached to one of your fingers to monitor your oxygen levels and pulse rate. We will ask you to walk up and down a corridor close to the lung function laboratory, for six minutes, accompanied by one of our members of staff. We will also measure how far you have walked.

We may be asked to assess how well your airways respond to medication. 

After completing the routine tests, you will be asked to breathe in a controlled dose of an inhaler (usually Salbutamol) through a small breathing device called a spacer. You will then take a seat in the waiting area and after 15 minutes will be asked to repeat the flow-volume loop. 

This will demonstrate how much your airways have been opened up by the inhaler.

• You can eat and drink as normal but should avoid eating a heavy meal two hours before the test
• You should wear loose, comfortable clothing that does not restrict your breathing
• Try not to smoke for at least 24 hours and refrain from drinking alcohol for at least 4 hours before the test
• Do not perform any rigorous exercise in the 30 minutes before your tests
• If you use inhalers
• If you take inhaled steroids, such as Flixotide, or steroids in tablet form, you can continue to use them as prescribed by your doctor
• If you use Ventolin, please do not take for 4 hours before your tests
• If you take Atrovent, please do not take for 6 hours before your tests
• You should stop taking Serevent 12 hours before your tests

If it is difficult to manage without your inhaler, please continue to use it when required but make a note of the time you take it and inform a member of staff in the lung function laboratory when you arrive for your tests.

Please let us know if you have recently:

• had any operations on your chest, abdomen or eyes
• broken or cracked a rib
• had any problems with your neck vertebrae
• had a collapsed lung

You should not have any side effects during or after the tests. 

The tests do not cause any pain or discomfort. However, you may feel a little tired afterwards. This is quite normal and will disappear quickly.

During the tests, you may feel a little breathless or light-headed, as your lungs are working harder than they would normally do. Should you need to rest between tests, have any pain or experience any other problems during the tests, please tell a member of staff. We will stop the tests and give you time until you feel well enough to continue.

The lung function laboratory at UCLH is situated on the first floor podium within the outpatients department, in Clinic E, and can be reached either by stairs or by lift.

Please contact the lung function unit as soon as possible on 020 3447 3112 so that we can give your appointment to another patient.

We will then offer you an alternative appointment date or time.

The lab is based within the outpatient department on the first floor podium at UCH.