[COPD: spirometry in general medicine].

Chronic Obstructive Pulmonary Disease (COPD) is a major cause of chronic morbidity and mortality throughout the world. COPD typically develops for a number of years before seeking medical help. Early detection by primary care physicians is a unique opportunity to intervene when the disease is not yet a health problem. COPD is characterized by airflow limitation that is not fully reversible. Pulmonary function test is thus the cornerstone for the early diagnosis of this disease. Determination of two lung volumes is enough to detect airway obstruction by spirometry: the Force Expiratory Volume during the first second (FEV1) of expiration and the Vital Capacity. Unlike electrocardiography, the procedure is a key stage in the performance of a spirometry. However, with some precautions described in the present paper, the manoeuvre is easy to perform properly. Technical considerations and limitations are also described. The interpretation of the results obtained needs a good understanding of the "normal value" and of the definition of an obstructive defect. When an obstruction is demonstrated with this simple test, it must be completed by more advanced tests to confirm the nature of the obstruction. Among these tests, the bronchodilators challenge testing, the evaluation of hyperinflation by plethysmography and the diffusing capacity of the lungs are the most currently realised tests in pulmonary function laboratories. Early detection and accurate diagnosis are necessary steps to improve the management and prevention of COPD.