The point of pulmonary function tests, or lung function tests as they are often called, is to investigate how well you are breathing and how efficiently oxygen is getting into your body. Large studies have established what is ‘normal’ for men and women of various ages and your test will compare your lung function with the ‘optimum’ for your age. If your lung function is lower than it should be, this indicates that we need to find out why.

Pulmonary function testing is also done to monitor the progression of chronic diseases such as chronic obstructive pulmonary disease (COPD), cystic fibrosis and severe asthma. It can reveal whether a treatment is working well, or if inhaling a toxic substance (such as smoke during a fire) has damaged your lungs.

What is spirometry?

Spirometry, the most common lung function test, is available at The Physicians’ Clinic and is done on an outpatient basis. It involves breathing in and then blowing out through a mouthpiece that is attached to a spirometer as hard and for as long as you can. The spirometer measures how much air comes out of your lungs, so helps to measure your lung volume and also measures the rate at which you can blow out. You will need to repeat the test several times to provide an accurate assessment so a spirometer tests usually takes about half an hour.

How do I prepare for a lung function test?

There are no special preparations but you will be more comfortable if you do not have a large meal within a couple of hours of your test. If you are a smoker, you should not smoke on the day of the test. If you have asthma or you are taking medication for a known lung problem, your consultant will advise you about whether to continue with this before the test. You may be given a bronchodilator or other drugs during the lung function test. If you feel unwell, dizzy or breathless during the testing, you need to alert us immediately.

What happens after lung function testing?

You will see your consultant again once the results are available and you will then discuss either a new course of treatment or a change to your current treatment.