Hyperinflated lungs can be caused by obstructions in the passages that deliver air to your lung tissue. Air gets trapped within the lung and causes it to overinflate. Hyperinflation can also occur when the air sacs in your lungs become less elastic, which interferes with the expulsion of air from your lungs.
One of the most common causes of hyperinflated lungs is chronic obstructive pulmonary disease (COPD) — a disorder that includes emphysema. Lung problems such as asthma and cystic fibrosis can also cause hyperinflation.
In some cases, lungs may appear hyperinflated on X-rays for reasons unrelated to lung function. If you aren't experiencing shortness of breath, there's probably nothing to worry about. But the only way to know whether you have something that causes truly hyperinflated lungs is to do a lung function test. If your lung function is abnormal, you should see a lung specialist to identify and treat the underlying problem.