Final answer:
A definitive diagnosis of COPD is made using Spirometry, a test that measures the rate of air expelling from the lungs, assessing lung function for obstructive conditions like COPD.
Step-by-step explanation:
The diagnosis of Chronic Obstructive Pulmonary Disease (COPD) can be firmly made by option A, Spirometry. This diagnostic tool measures the rate at which air can be expelled from the lung, which is critical in detecting obstructive diseases like COPD. Spirometry is an essential test because it provides objective information about pulmonary function, specifically the volume of air an individual can exhale and the speed of the exhalation.
COPD, which can result from conditions such as chronic bronchitis or emphysema, leads to a breakdown of connective tissues in the lungs, reducing the number and elasticity of alveoli. Consequently, patients are unable to fully exhale air from the lungs, causing air to become trapped and resulting in hampered gas exchange. Low oxygen levels and an excess of carbon dioxide in the blood can be consequences of this trapped air.
While other methods such as X-ray chest, auscultation, or blood tests can provide additional information or assist in assessing COPD, it is the spirometry test that is the cornerstone of a definitive diagnosis. Understanding and interpreting spirometry test results is essential in diagnosing respiratory diseases or determining the effectiveness of disease treatment.