Chronic obstructive pulmonary disease, or COPD, one of many chronic lung diseases, is now the third leading cause of death, following heart disease and cancer. More than 15.3 million people have the disease and many don't realize it. Left untreated, COPD can worsen dramatically.

COPD is a disorder characterized by persistent obstruction to airflow through the lungs, usually caused by harmful inhaled particles such as those found in tobacco smoke. Yale Medicine, through the Chronic Obstructive Pulmonary Disease (COPD) Program, is at the forefront of the research to develop more targeted, individualized treatments for patients.

Emphysema and chronic bronchitis are forms of chronic obstructive pulmonary disease (COPD).

Emphysema is a lung condition that damages tiny air sacs in the lungs, impairing their ability to introduce oxygen into the lungs and remove carbon dioxide from them.

In chronic bronchitis, the air passages (bronchial tubes) become inflamed and restrict airflow, resulting in chronic coughing and sputum (mucus) production.

Primary symptoms of chronic obstructive pulmonary disease (COPD) include:

• Chronic cough that may be intermittent and may be accompanied by mucus
• Difficulty performing activities due to shortness of breath and/or leg fatigue. In severe cases, this may even include daily activities, such as bathing, dressing, walking, or eating.
• Intermittent wheezing
• Persistent shortness of breath that worsens with exertion and over time

COPD symptoms are also very common in other conditions, such as heart disease. Diagnostic tests are recommended if a patient is experiencing some of the primary symptoms along with a history of exposure to smoke, chemicals or fumes, or a family history of COPD.

Common secondary symptoms of COPD include wheezing, chest tightness, fatigue, and difficulty sleeping. Given that COPD may be concurrent with conditions such as heart disease, anxiety, depression, and anemia, patients with those conditions may also experience additional associated symptoms.

The severity of COPD symptoms often varies somewhat from day to day. It is not unusual for patients with COPD to experience a sudden increase in symptoms over and above what is typical for them. This is called an acute exacerbation, characterized by worsening lung function and quality of life, as well as increased risk of need for urgent medical care.

While the severity of acute COPD exacerbation is different for every person, patients usually require a change in medication during the event.

A combination of environmental exposures and genetics increases a person’s risk of developing chronic obstructive pulmonary disease (COPD), including:

• Smoking: Regular exposure to tobacco smoke, firsthand and/or secondhand
• Other irritants: Frequent exposure to other non-tobacco smokes (e.g., cannabis), industrial chemicals and fumes, and indoor air pollutants such as biomass fuels (e.g., coal)
• Genetics: Alpha-1 antitrypsin deficiency, a genetic condition associated with lung disease. It’s found to be a cause of about 1% of COPD cases.
• Age: There is a higher correlation of COPD with middle-to-older age patients. In 2011, more than 90% of emphysema cases occurred among people aged 45 and older.
• Poverty: Studies show a high prevalence of COPD in poor areas and countries.
• Early childhood respiratory complications: Studies have found that patients who had childhood lung conditions are more likely to develop COPD later in life.

Diagnosis begins with lung function testing. The most common method is spirometry, a simple test that measures the amount and speed of air that a patient blows into a mouthpiece.

If necessary, other lung function tests may also be conducted, including:

• A second spirometry, 10 to 30 minutes after a patient inhales bronchodilators (medications used to dilate the bronchial tubes).
• Testing lung volumes to measure the amount of air a patient can inhale and test for the presence and extent of trapped air
• Testing lung diffusing capacity to measure the ability of the lungs to transfer oxygen from the air sacs to the blood moving through the lung’s blood vessels. In this test, the patient inhales air containing a small amount of a tracer gas, such as carbon monoxide. The patient then holds his or her breath for 10 seconds, then rapidly exhales into a mouthpiece. This exhaled air is then analyzed to determine how much of the tracer gas was absorbed in the inhaled breath.

Additional diagnostics beyond lung function testing may also be performed on subsequent visits. This helps to rule out other conditions and to monitor and understand the complexity of the patient’s COPD:

• Chest X-ray
• Computerized tomography (CT) scan of the lungs
• A walking test, to evaluate shortness of breath and blood oxygen saturation level
• Various blood tests to screen for anemia or alpha-1 antitrypsin deficiency
• Overnight oxygen saturation monitoring
• Arterial blood gas tests to measure oxygen, carbon dioxide levels and blood acidity
• Ultrasound of the heart and/or stress testing to screen for heart disease

COPD is not curable, but it is treatable. Most patients are prescribed a combination of lifestyle changes and medical therapies, and rehabilitative therapies are recommended if symptoms persist. Surgery may be considered for some patients with very severe disease.

Treatment of COPD depends on the specifics and severity of a patient’s condition and can include:

Lifestyle changes: Cessation of smoke exposure is the first step in treatment.

Medical therapies: Most patients are treated with bronchodilators, which dilate the bronchial tubes (air passageways into the lungs). Some people benefit from inhaled corticosteroids, which reduce airway inflammation and mucus. Phosphodiesterase inhibitors may be used for patients with chronic bronchitis who have frequent exacerbations despite the use of inhaled bronchodilators. Additionally, noninvasive ventilation may be used for patients who have trouble breathing during sleep, and alpha-1 antitrypsin augmentation may be used for patients with a genetic deficiency of the enzyme.

Oxygen therapy: Supplemental oxygen is recommended for those with low blood oxygen levels at rest, during exertion, and/or during sleep.

Physical therapies: Pulmonary rehabilitation, a supervised program of physical exercise and education, is recommended if patients remain symptomatic despite regular use of their medications. This helps patients reduce their shortness of breath, improves their ability to exercise and do activities of daily living, and works in conjunction with their health care providers to maintain control of and adjust to the disease. Regular physical activity in daily life is also recommended.

Surgery: Lung volume reduction surgery may be recommended for some individuals with emphysema to allow the remaining lung to work more effectively. In some severe cases where the patient has no relief from medical therapies, lung transplantation surgery may be recommended.

Vaccinations: Flu, pneumonia, and COVID-19 vaccinations are recommended as preventive measures, since these conditions can cause severe illness for people with COPD.

This article was medically reviewed by Maor Sauler, MD, a Yale Medicine doctor who specializes in adult pulmonary medicine and critical care.