A lung function test is a blowing test. It helps to diagnose different types of lung diseases – obstructive or restrictive lung diseases. Children from the age of five can start doing spirometry.
How is the test done
The test is done by blowing into a handheld lung function machine, via a mouthpiece. First you breathe in fully, and then blow out forcefully, as fast and as hard as you can, until your lungs are completely empty. It’s a bit like blowing out all the candles on a cake. It can take several tries to get the technique perfect, especially if it is the first test done. The best of three attempts is usually used as the final reading.
What does the test measure
FEV1 is the forced expiratory volume in one second and indicates if there is obstruction to the smaller airways of the lungs, like in asthma.
FVC is the forced vital capacity and is an indirect measure of your lung size.
Several other volumes are also measured, which helps determine the type of lung problem you have.
Bronchodilator response test
You may need to do a bronchodialator test, if the diagnosis is not certain. After doing an initial lung function test, you take a bronchodilator (inhaler that opens your lungs), and then do another lung function test.
Usually the second test is done fifteen minutes after the inhaler is given, to allow time for the lungs to open. The results before and after the bronchodilator can be compared to give a more accurate diagnosis, and to keep a record of progress in controlling the lung condition.
