Emphysema · What Is It, Difference From COPD, and More

Emphysema is a lung disease characterized by damage to lung parenchyma, which is the lung tissue responsible for gas exchange. It’s one of the most common preventable lung diseases globally.  

The lung parenchyma mainly consists of alveoli, or tiny air-filled sacs in the lungs. Within the alveoli, carbon dioxide is transferred from the arterial blood to the alveoli to be exhaled, while oxygen is transferred from the alveoli to the venous blood. With emphysema, alveoli are damaged, leading to impaired gas exchange.  

Chronic lung damage due to cigarette smoking causes the majority of cases of emphysema. Exposure to secondhand smoke also greatly increases the risk of developing emphysema. Other causes of lung damage include exposure to air pollution, chemical fumes, and dust, such as that from coal mining or wood smoke. Long-term exposure to these directly damages the lung tissue and causes an immune response, leading to inflammation and obstruction of airflow. As a result, gas exchange becomes increasingly obstructed, leading to progressively worsening symptoms. 

Some individuals may also develop emphysema as a result of certain chronic diseases like cystic fibrosis; or genetic abnormalities, such as alpha-1 antitrypsin deficiency, which is an inherited condition characterized by a deficiency in the protein that helps prevent lung damage.  

• Chronic obstructive pulmonary disease: Emphysema is a subtype of COPD, often caused by long-term smoking.
• Alpha-1 antitrypsin deficiency: A genetic cause of early-onset emphysema, especially in non-smokers or younger patients.
• Chronic bronchitis: Often coexists with emphysema and presents with chronic productive cough.

• Asthma: May mimic COPD but is typically reversible with bronchodilators and has an earlier onset.
• Bronchiectasis: Can present with chronic cough and sputum production but involves airway dilation and recurrent infections.
• Interstitial lung disease: May present with dyspnea and abnormal imaging but typically shows restrictive patterns on pulmonary function tests.
• Heart failure (especially right-sided): Can cause dyspnea and wheezing, mimicking obstructive lung disease.

• Pulmonary Langerhans cell histiocytosis: A smoking-related lung disease that can cause cystic changes similar to emphysema.
• Tuberculosis: Can cause cavitary lesions and chronic respiratory symptoms but has a different radiographic and clinical profile.
• Sarcoidosis: May involve the lungs but typically presents with hilar lymphadenopathy and granulomatous inflammation.

• Pneumothorax: Spontaneous or secondary to emphysema; presents with sudden dyspnea and requires urgent intervention.
• Pulmonary embolism: Can mimic COPD exacerbation with acute dyspnea and hypoxia.
• Lung cancer: Especially in smokers; may present with cough, weight loss, or hemoptysis.
• Severe COPD exacerbation with respiratory failure: Requires prompt recognition and management to prevent decompensation.

Diagnosis often begins with a history and physical examination. The physical exam usually includes measurements of lung function using spirometry and pulse oximetry. Spirometry is a pulmonary function test that measures the quantity of air an individual can inhale and exhale as well as the speed at which air is exhaled. This is recorded by the forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), respectively. The ratio of FEV1/FVC can assist in determining whether there is a breathing limitation present as seen with emphysema.  

On the other hand, pulse oximetry is a test that measures the percentage of oxygen molecules attached to hemoglobin, or the saturation. It’s a quick, painless, and simple method to evaluate oxygen content within the blood. 

Blood samples may also be used to evaluate arterial blood gas levels. A chest X-ray and electrocardiogram may also be used to rule out other possible causes of the individual's symptoms, such as chronic bronchitis, pneumonia, or heart disease. 

Although emphysema cannot be cured, treatments can help manage symptoms and slow the progression of the disease while minimizing complications. If associated with tobacco smoking, cessation of smoking is highly encouraged. If necessary, emphysema may also be managed with medications, such as long-acting bronchodilators, inhaled steroids, or a combination of both. Short-acting bronchodilators may also be prescribed for flares. For some, oxygen therapy may be required to provide the individual with supplemental oxygen.  

Typically, physical therapy is also prescribed to improve muscle strength and movement and maintain activity tolerance. Some individuals with emphysema may take part in a pulmonary rehabilitation program, which provides comprehensive and personalized care designed by an interdisciplinary team. These programs consist of a wide range of activities, including education, exercises, and peer support.  

If emphysema is severe, surgical procedures may be recommended. These may include a bullectomy to remove giant bullae (i.e., large air sacs created by the merging of hundreds of destroyed alveoli); a lung volume reduction surgery to remove damaged lung tissue; or a lung transplant.  

In addition, vaccinations, such as for pneumonia, influenza, and respiratory syncytial virus (RSV) are recommended due to the increased risk of infection and subsequent complications.