What are the key diagnostic criteria for emphysema in a patient presenting with respiratory symptoms?

Key diagnostic criteria for emphysema in a patient presenting with respiratory symptoms include:

• Presence of respiratory symptoms such as exertional breathlessness, chronic cough, regular sputum production, wheeze, and frequent winter bronchitis, especially in people over 35 with a history of smoking or other risk factors.
• Confirmation of airflow obstruction by spirometry showing a post-bronchodilator FEV1/FVC ratio of less than 0.7, which supports the diagnosis of COPD, of which emphysema is a subtype.
• Assessment of severity of airflow obstruction by the degree of reduction in FEV1 post-bronchodilator.
• Consideration of additional investigations such as chest CT scan to identify emphysematous changes, especially if symptoms are disproportionate to spirometric impairment or to exclude other diagnoses.
• Exclusion of alternative diagnoses such as asthma, cardiac disease, or bronchiectasis through clinical history, examination, and relevant tests.
• Consideration of alpha-1 antitrypsin deficiency testing in younger patients, those with minimal smoking history, or family history, as this can cause emphysema.

These criteria align with the diagnosis of COPD, which includes emphysema as a component, and rely primarily on clinical presentation supported by spirometry and imaging where indicated ¹.