Emphysema

Emphysema is a lung disease characterized by damage to lung parenchyma, which is the lung tissue that carries out gas exchange. It is one of the most common preventable lung diseases globally. 

The lung parenchyma mainly consists of alveoli, or tiny air-filled sacs in the lungs. At the alveoli, the carbon dioxide is transferred from the arterial blood to the exhaled air, while oxygen is transferred from the inhaled air to the venous blood. With emphysema, the damaged alveoli impairs this gas exchange. 

COPD stands for chronic obstructive pulmonary disease, which is a general term for chronic lung diseases, and occurs when airflow is blocked, or obstructed, from entering the lungs. The two primary types of COPD are emphysema and chronic bronchitis. Chronic bronchitis refers to long-term inflammation of the large air passageways in the lungs, called the bronchi, which increases susceptibility to lung infections. In most cases, individuals with COPD will experience both emphysema and chronic bronchitis; however, individuals can also present with just one. 

Chronic lung damage due to cigarette smoking causes about 90% of all emphysema cases in the United States. Exposure to secondhand smoke also greatly increases risk of developing emphysema. Other causes of lung damage include exposure to air pollution, chemical fumes, and dust (i.e., from coal mining or wood smoke). Long-term exposure to these aforementioned toxic chemicals directly damages the lung tissue and causes an immune system response, leading to inflammation and the obstruction of airflow. As a result, gas exchange may become more and more obstructed, leading to progressively worsening symptoms.

Some individuals may also develop emphysema as a result of chronic disease, lung abnormalities, or genetic abnormalities. For example, alpha-1 antitrypsin deficiency, characterized by a deficiency in the protein that inhibits elastase, can cause emphysema. Inflammatory cells, like neutrophils, release elastase to break down the elastin that is located on the membrane of the alveoli. When alpha-1 antitrypsin is deficient, the unregulated elastase leads to increased lung damage over time, thereby causing emphysema.

The most common symptoms of emphysema include progressively worsening shortness of breath, a productive cough (i.e., with mucus), wheezing, and weight loss. Early on in disease progression, individuals may only experience few, if any, signs and symptoms. Often, the only symptoms present may be prolonged expiration or wheezing on forced exhalation. When the disease becomes severe, people with emphysema may also present with a barrel chest, which gives the appearance that the individual is always holding a deep breath. Physical activity may be limited due to increased fatigue and weakness from insufficient blood oxygenation. 

Diagnosis often begins with medical examination, including history of present illness; medical, family, and social history; and a physical examination. The physical exam usually includes measurements of lung function through spirometry and pulse oximetry. Spirometry is a pulmonary function test that measures the quantity of air a person can inhale and exhale as well as the speed at which air is exhaled.This is recorded by the FVC (forced vital capacity) and FEV1 (forced expiratory volume in one second), 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 oxygen saturation of blood. Blood samples may also be tested to provide accurate measurements of the arterial blood gas levels (i.e. oxygen and carbon dioxide). Chest X-rays and electrocardiograms 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, treatment typically involves reducing risk factors and managing symptoms in order to slow the progression and minimize complications. If associated with tobacco smoking, cessation of smoking is highly encouraged to reduce progression of emphysema and COPD. If necessary, emphysema may also be managed with medications, such as long-acting bronchodilators (e.g., tiotropium), inhaled steroids (e.g., fluticasone), or a combination of both. Short-acting bronchodilators (e.g., albuterol) may also be prescribed for exacerbated events. 

In the case that there is not enough oxygen in an individual’s blood, oxygen therapy may be administered to provide the individual with supplemental oxygen. 

Typically, physical therapy is also prescribed to improve muscle strength and movement. Some individuals with emphysema may take part in a pulmonary rehabilitation program, which provides comprehensive and personalized care designed by a team of healthcare providers (i.e., doctors, nurses, dieticians, etc.). These programs consist of a wide range of activities, including education, exercises, and peer support. 

When emphysema is severe, surgical procedures may be utilized. Possible surgeries include a bullectomy to remove giant bullae (i.e., large air sacs created by combining hundreds of destroyed alveoli), a lung volume reduction surgery to remove damaged lung tissue, or a lung transplant. 

In addition, vaccinations for pneumonia and the annual flu are recommended for people with emphysema due to their increased risk of severe respiratory disease.

Emphysema, a common lung disease characterized by damage to alveoli, is one of the major types of chronic obstructive pulmonary disease (COPD). Emphysema can be caused by anything that damages the lung tissue over a long period of time, most commonly long-term tobacco smoking. Signs and symptoms of emphysema typically include shortness of breath, productive cough, or wheezing. Emphysema is often diagnosed by a medical examination, including lung function testing. Treatment involves minimizing exposure to damage causing agents (e.g., stopping smoking); taking medications to improve breathing, like bronchodilators; and physical therapy.