Tests performed to determine if someone is suffering from emphysema include
Pulmonary function tests (PFTs) to measure how much air your lungs can hold. These tests also measure the extent of gas exchanged between your alveolar wall and capillary membrane.
Chest X-ray to rule out other possible lung problems.
Arterial blood gas analysis, to measure how well your lungs transfer oxygen and remove CO2 in the bloodstream.
Computerized tomography (CT) scan, which can detect emphysema more reliably and sooner than a chest X-ray.