Pulmonary (pool-mo-NARE-ee) function tests measure how well your child’s lungs are working. They measure how fast air can flow through the airways, how much air is in the lungs and how stiff the lungs are. This information is important in diagnosing breathing problems and checking to see if current treatments are working. The results of these tests can show if your child’s lungs or airways are obstructed (blocked) in any way because of asthma or other conditions that affect breathing.
In older children who are able to follow instructions, lung function is checked through a test called spirometry, which measures breath capacity as a child blows out into a tube. When children are too young—or are unable—to follow instructions, lung function is measured with infant pulmonary function testing (iPFT). iPFT uses special equipment to measure lung function while the child is asleep. iPFTs are very safe and can be performed even on tiny babies.