We have a few different types of lung function tests in young children. We can perform lung function in infants and preschool children using the same techniques, but slightly different ways of doing them. We use three different lung function tests in young children.
This test is designed to find out how evenly children breathe. We do this because we know that lung disease in cystic fibrosis begins in the edges of the lungs and results in more air going to some parts of the lungs (the normal parts) that to others (parts with early lung disease). In this test children breathe in a tracer gas to mix through the lungs. We then turn off the gas and measure how quickly children breathe the gas out. Children with normal lungs breathe the gas out of their lungs quickly, but children with early lung disease take longer to clear the gas from their lungs.
This test uses a sound wave to measure children's lung function. It is similar to the way a fisherman uses sonar to find fish. The sound waves that are made by a loud speaker change depending on how resistant the airways are and how stiff they are.
Lung function is measured in adults and older children by asking them to take in a big breath and to blow out as fast as they can. We use this lung function test (spirometry) in children who are older than 5 years in combination with the first two lung function tests. This test requires children to take a big breath in and blow out as fast as they can for a period of 6 seconds. Babies (children under 2) cannot do this so we help them. We help them take a big breath in by gently filling their lungs with air from a pump. When their lungs are full we inflate an inflatable jacket, which is wrapped around their chest, to help them blow out as fast as they can. This test was one of the first developed for measuring lung function in babies and has been used all around the world for the last 20 to 30 years. This test gives us similar information about lung function in babies as it does in adults. Those with abnormal lung function cannot blow out as much air as quickly as those with normal lung function.
We have found that infants with cystic fibrosis have worse lung function compared to healthy controls. We are investigating how lung function changes with an infection and with the presence of inflammation. We are also looking at how lung function changes over time and if we can predict how sick children are, or will be, based on their lung function in infancy.
Last updated 26 September 2008
