Can you tell me how could chronic obstructive pulmonary disease affect your gas exchange?

COPD. Chronic obstructive pulmonary disease (COPD) is mainly a problem that results in difficulty exhaling air due to airway narrowing. This results in air being trapped within the lung because it can't be exhaled, the trapped air doesn't participate in gas exchange. Also in severe COPD, many people also have emphysema which is destruction of lung tissue that participates in gas exchange.