Hyperinflated lungs occur when air gets trapped in the lungs and causes them to overinflate. Hyperinflated lungs can be caused by blockages in the air passages or by air sacs that are less elastic, which interferes with the expulsion of air from the lungs.
Hyperinflated lungs are often seen in people with chronic obstructive pulmonary disease (COPD) — a disorder that includes emphysema. Certain lung problems, such as asthma and cystic fibrosis, also can cause hyperinflation.
In some cases, lungs can appear hyperinflated on X-rays for reasons unrelated to lung function. If it isn't clear what's causing the hyperinflation, your doctor might recommend additional testing, such as a computerized tomography (CT) of the chest and pulmonary function tests.