If your child is able to (usually after the age of 5 or 6) they may be asked to perform a lung function test (spirometry) when they attend. This is a test to see how well the air flows out of the lungs. One of the specialist physiologists at the clinic will carefully explain the test to you and your child at the time. The results of the test will be known to the doctor when you are seen in the clinic, and can help the doctor in making a diagnosis of your child’s problem, or how to alter treatment to give your child maximum benefit.