Chronic Obstructive Pulmonary Disease (COPD) diagnosis is made by measuring lung function. Spirometry is the name given to the test used to measure how well you can breathe. The test requires you to take a deep breath and blow out as fast as possible into a small device called a Spirometer. Spirometry should be performed both before and after inhalation of bronchodilating medicines. It is not possible to establish the COPD diagnosis without spirometry.
If spirometry shows a reduced airflow through the airways, the patient is having obstructive reduction of lung function. If the lung function is still reduced after inhalation of bronchodilating medicines, the obstruction is chronic and synonymous with chronic obstructive pulmonary disease. Please note that asthma is also an obstructive lung disease but that inhalation of bronchodilating medicines normalizes the lung function. Asthma could therefore be called a periodically obstructive lung disease. Both asthma and COPD are chronic diseases but only COPD has chronic obstruction.
Spirometry is the basis of determining the severity of the disease, the more reduced the lung function is, the more severe the disease is. People who have a lung function under 50% of what is normal for their age group and sex, that is people who have lost more than half of their lung function, are considered to have a severe disease.
In diagnosing COPD a chest X-ray, and sometimes a computed tomography of the chest, should also be taken. These examinations are done primarily to exclude other causes of the symptoms.
If you suspect you have COPD, please contact your Doctor or other health professional for more information and advice.
UK/GEN/15/0058c Date of preparation: December 2015