which diagnostic procedure is commonly used to confirm the diagnosis of COPD?

Mr. Santos, a 65-year-old male, presents to the clinic with complaints of chronic cough, dyspnea and wheezing. He has a history of smoking for 40 years and has been exposed to occupational dust for the past 20 years. Physical examination reveals barrel chest, decreased breath sounds and prolonged expiration. Spirometry shows a reduced Fev1 / FVC ratio.