The chest x-ray can reveal clues about the presence of chronic lung disease (COPD), especially if the amount of disease in the lung is moderate or severe. But it does not provide an accurate measure of disease, and in fact, the x-ray can appear normal even in a significantly diseased lung. The signs of COPD that we look for in an x-ray are:
- Increased lung size.
- Decreased normal lung blood vessels and other markings (both of these findings are more common in emphysema).
- Flattening of the diaphragm (long muscle separating the chest and abdomen).
- Increased air between the front part of the chest and the heart.
In most cases, a diagnosis of COPD should not be made from a chest x-ray. If COPD is suspected on the basis of an x-ray, further studies should be done.
Pulmonary Or Lung Function Studies
Lung function studies are used to better clarify the state of disease in the lungs. The most common of these tests is spirometry.
Spirometry
Spirometry is designed to measure the amount of air you can move in and out of your lungs and how quickly you can move it. You do this test by breathing through a tube connected to a machine that measures volumes and flows. First you take several normal breaths (called tidal breaths) after which you take in as big a breath as you can and blow it out as fast as you can. Recording the volumes and flow rates of these breaths provides a measurement of the maximum volume, or amount, of air you can move in and out of your lungs (vital capacity, or FVC) and how rapidly you can breathe it out of your lungs (forced expiratory volume or FEV).
