Lung function testing in children
Lung (or pulmonary) function tests are performed for a variety of reasons in children. They may help with making the diagnosis and determining the severity of respiratory disease, and also help with monitoring response to treatment.
What types of tests are available?
The more commonly used tests in older children include spirometry and peak flow measurement. Other tests, which are available at respiratory departments in teaching hospitals, include exercise testing and measurement of lung volumes.
There are also some more specialised tests that have mainly been used in research but are now beginning to be used in clinical practice.
Spirometry
Spirometry is a test of lung function that measures the amount of air breathed in and out. Children older than 7 years are usually able to perform spirometry. They may be tested with a spirometer in their doctor’s surgery or local laboratory.
Spirometry gives a measure of the maximum amount of air a person can breathe out (after taking in a deep breath) and how much they can breathe out in one second.
Spirometry is commonly used in older children to help make a diagnosis of asthma, to determine how severe asthma is, and monitor the success of treatment. It is also part of the routine management of people with respiratory diseases that get worse with time (such as cystic fibrosis) or progressive neuromuscular conditions (such as Duchenne muscular dystrophy).
Peak flow measurement
Peak flow meters measure the greatest speed reached when a person breathes out through the meter as hard and fast as possible (having taken a deep breath in first). Peak flow measurement is not the recommended test for diagnosing asthma.
A peak flow meter is a small portable device that can generally be used by children older than 7 years. Your doctor may suggest using a peak flow meter at home as part of monitoring the status of your child’s asthma and the success of their treatment, but spirometry is the best test to determine the severity of asthma at any given point in time.
Other tests
Lung volume measurements are used for distinguishing between people with obstructive airways disease and air trapping (such as may occur in cystic fibrosis) and people with restrictive lung disease (such as in some neuromuscular diseases).
Exercise testing may be used to assess older children (older than 8 years) who complain of shortness of breath, often associated with exercise. It can help to determine whether the diagnosis may be asthma, restrictive lung disease, anxiety or lack of fitness.
Last Reviewed: 08 June 2007
