Chronic obstructive pulmonary disease, or COPD, is an umbrella term for lung conditions that block airflow and make breathing difficult.
"Think of COPD as a spectrum of disease, with chronic bronchitis on one end and emphysema on the other," says?Jeffrey Michaelson, MD, a pulmonologist with WellStar Medical Group in Marietta, Georgia.
What Is Emphysema?
Emphysema occurs when the air sacs of the lungs (alveoli) become damaged and enlarged, causing breathlessness. Each lung has an average of 480 million alveoli, according to past research. (2)
When you inhale, the alveoli expand and stretch, taking in oxygen and transporting it to the blood via small capillary vessels within their thin walls. Those same capillary vessels also transport carbon dioxide out of the blood; when you exhale, the alveoli deflate,?expelling the carbon dioxide out of the body through the airways.
In people with emphysema, the walls of the alveoli are damaged and the alveoli lose their normal elasticity, causing the smaller airways to the lungs (bronchioles) to collapse.
“Symptoms of emphysema deal with progressive shortness of breath that limits activity,” says Dr. Michaelson. Other common symptoms include chronic cough, frequent respiratory infections, wheezing, reduced appetite, and fatigue.
What Is Chronic Bronchitis?
Bronchitis?is an inflammation of the bronchial tubes (airways), which bring air to and from the lungs. When the bronchial tubes are inflamed, the lining, or mucous membrane, of the airways swells and grows thicker. It also produces an excess amount of?mucus.
Bronchitis can be either acute or chronic. Acute bronchitis typically results from temporary infections and lung irritants, and is commonly caused by the same viruses that cause colds and the flu. Most cases of acute bronchitis clear up within a few days.
Chronic bronchitis is a far more serious, incurable lung disease involving periods of persistent coughing that signals underlying structural changes to the bronchial system. Aside from the mucus-laden cough, people with chronic bronchitis experience shortness of breath, tightness of the chest, wheezing, and fatigue.
COPD symptoms can develop slowly. There may be no apparent symptoms at first.
Early signs and symptoms of COPD may be mild and include:
- Persistent cough that may contain mucus, referred to as “smoker’s cough”
- Chest tightness
- Dyspnea, or shortness of breath that worsens with activity
As the condition worsens, other symptoms may develop, such as:
- Cyanosis, a blueness of the skin, particularly the lips and fingernail beds
- Weight loss
- Rapid heartbeat
- Edema, or swelling of the feet and ankles
In severe cases, COPD may also cause mental confusion and disorientation.
People with COPD often experience exacerbations, or periods of time when symptoms worsen, which usually are the result of a respiratory infection or an increase in air pollutants.
Signs and Symptoms of COPD
The Stages of COPD and Their Symptoms
The?Global Initiative for Chronic Obstructive Lung Disease (GOLD)?— which was launched in collaboration with the NHLBI, the National Institutes of Health (NIH), and the World Health Organization (WHO) — established a system to determine the severity of airflow restriction, or stages, of COPD.
The GOLD guidelines break down COPD severity into four stages based on a unit of measurement known as?forced expiratory volume (FEV1). FEV1 is the maximum amount of air exhaled by the lungs in one second. The lower the FEV1, the lower a person’s lung capacity and the more severe the COPD.
By comparing a patient’s FEV1 with expected values considered to be healthy, a doctor calculates a percentage that determines what stage COPD a person has, notes the Lung Institute. (3)
The four COPD stages or grades are:
- Mild COPD, characterized by an FEV1 of around 80 percent or more of the expected value
- Moderate COPD, characterized by an FEV1 between 50 percent and 80 percent
- Severe COPD, characterized by an FEV1 between 30 percent and 50 percent
- Very Severe COPD, characterized by an FEV1 of less than 30 percent
Another COPD-related measurement is the forced vital capacity (FVC) test, which is the amount of air a person can force out of the lungs after inhaling as much as possible.
The ratio of FEV1 to FVC is used to determine lung capacity — an FEV1/FVC ratio of around 80 percent is considered healthy. All four COPD stages are characterized by an FEV1/FVC ratio of less than 70 percent. (3)
Other factors — including the severity of symptoms, risk of exacerbations, and the presence of other medical conditions — are relevant to patients’ reality of living with COPD and their prognosis, and are included in newer staging systems, such as the revised GOLD classification.
Stage 1: Mild COPD
Mild COPD involves minor airflow limitation.
Symptoms may include:
- Some coughing
- Coughing up mucus or sputum
- Difficulty breathing or shortness of breath (dyspnea)
Treatment may include a short-acting bronchodilator and smoking cessation if the patient smokes.
Stage 2: Moderate COPD
With moderate COPD, airflow limitation begins to worsen.
Symptoms, which are similar to mild COPD, include:
- Chronic coughing
- Increased sputum production
Treatment may include long-acting inhalers and pulmonary rehabilitation.
Stage 3: Severe COPD
Severe COPD means that lung function has been seriously impaired, and the condition is having a noticeable impact on the patient’s quality of life.
In addition to chronic coughing, sputum, and dyspnea, severe COPD symptoms include:
- Weight loss
- Tiredness and difficulty exercising
- Respiratory infections
Stage 4: Very Severe or End-Stage COPD
Very severe COPD, also known as end-stage COPD, means that the patient’s breathing difficulties have become life-threatening. The disease starts to affect the heart and circulatory system.
In addition to severe COPD symptoms, signs of end-stage COPD include:
- Blueness of the lips or fingernail beds (cyanosis)
- Chronic respiratory failure
Treatment may require oxygen therapy or surgery.
Causes and Risk Factors of COPD
All forms of COPD, including emphysema and chronic bronchitis, stem from airborne irritants that are inhaled.
Smoking is the main cause of COPD, though nonsmokers can also get the disease. According to the?American Lung Association, between 85 and 90 percent of all COPD cases are caused by cigarette smoking. (4) Long-term exposure to other lung irritants, such as secondhand smoke, can also contribute to COPD, notes the Centers for Disease Control and Prevention (CDC). (5)
Most people who develop COPD symptoms are at least 40 years old. People younger than 40 years of age can have COPD, too, but it's uncommon.
In rare cases, emphysema can be caused by the hereditary disorder?alpha-1 antitrypsin (A1AT) deficiency. People with this deficiency have low levels of a protein made in the liver, which can lead to lung damage if exposed to airborne irritants.
Unlike some cases of emphysema, chronic bronchitis is not caused by the genetic disorder alpha-1 antitrypsin (A1AT) deficiency.
Other causes of COPD include:
- Indoor air pollution
- Exposure to dust and chemical fumes in the workplace
- Frequent childhood respiratory infections
How Is COPD Diagnosed?
Diagnosing COPD usually involves an assessment of the patient’s health history combined with performing certain tests.
To determine whether you have COPD, the doctor will typically begin by asking questions regarding symptoms, smoking habits, exposure to airborne irritants, and family history of COPD or the genetic disorder alpha-1 antitrypsin (A1AT) deficiency, which can cause emphysema.
A physical examination is performed to inspect the strength and function of your lungs and heart, and to look for any visible signs of COPD, such as cyanosis.
Your doctor may order one or more lung function tests, such as:
- Spirometry?This involves blowing into a tube connected to a spirometer, a machine that measures the airflow into and out of the lungs. This is frequently the only test needed to diagnose COPD.
- Bronchial Provocation Test?In this test, the patient undergoes spirometry after breathing in a certain drug (methacholine or a?histamine) to evaluate the sensitivity of your lungs. Pulmonologists only rarely order this test but they may use it when they strongly suspect COPD yet the initial spirometry test was normal.
- Exercise Tolerance Test?This can identify dyspnea and evaluate how exercise affects the ability of your heart and lungs to provide oxygen to, and remove carbon dioxide from, the bloodstream. This test is rarely done to diagnose COPD but rather to explore alternate diagnoses.
- Exercise for Desaturation Test?Also known as the six-minute walk test, this assessment measures your oxygen needs while at rest and during exercise.
Your doctor might also order blood tests and imaging scans, such as:
- Arterial Blood Gas Test?This?evaluates your lungs' gas exchange capabilities by measuring the amounts of oxygen and carbon dioxide in your blood.
- A1AT Deficiency Blood Test
- Chest X-rays?X-rays?are performed to look for lung enlargement, bronchial scarring, and the formation of air-filled cavities in the lungs called bullae.
- Computerized Tomography (CT) scans?CT scans?provide more information than typical X-rays, such as whether there is airway inflammation.
Other diagnostic tests may also be necessary, such as a heart test called electrocardiogram (EKG), bronchoscopy (where a thin tube with a camera is inserted into the airways to examine the lungs), and a lung or bronchial biopsy.
Treatment and Medication Options for COPD
Treatment focuses on relieving symptoms, improving quality of life, and correcting lifestyle habits that may worsen the condition.
To slow the progression of the disease, it's important to stop smoking and avoid exposure to lung irritants.
Pulmonary rehabilitation, which can improve your well-being, may include:
- A special exercise or activity plan to strengthen the muscles used for breathing
- Breathing strategies
- Psychological counseling
- Dietary changes to maintain a healthy weight
Medication that may be part of a COPD treatment plan may include:
- Bronchodilators (inhalers) to open the airways
- Steroids to reduce airway inflammation
- Antibiotics to treat respiratory infections
Duration of COPD
There is no cure for COPD and it's a chronic, lifelong condition. But treatment can help you manage symptoms and slow the progression of the disease, delaying the onset of later-stage COPD.
People can live a long time with COPD and life expectancy depends upon the stage of the disease. The BODE index is a tool that's used to predict mortality. It looks at four factors in people with COPD: body-mass index (B), degree of airflow obstruction (O) and dyspnea (D), and exercise capacity (E), as measured by a six-minute walk test. A higher score on the BODE index indicates a higher risk of death, per past research. (6)
Prevention of COPD
One of the best ways to prevent getting COPD is to never start smoking, or to stop smoking if you already do.
If you have trouble quitting smoking, there are numerous options to help you, including gums, patches, and prescription medication. Additionally, support groups and classes to help you quit smoking can often be found through hospitals, workplaces, and community associations.
Heavy and long-term exposure to various lung irritants, including air pollution, dust and chemical fumes in the workplace, and secondhand smoke, can also cause COPD.
Here are some tips to reduce your exposure to COPD-causing irritants:
- Make sure any wood-burning stove or fireplace is well ventilated.
- Stay indoors if there's noticeable air pollution outside.
- Make your home an environment free from secondhand smoke.
- If you work in an environment where you are exposed to chemical fumes and dust, speak with your supervisor about respiratory protective equipment and other ways to protect yourself.
Research and Statistics: Who Gets COPD?
Nearly 15.7 million Americans report having been diagnosed with COPD, according to the?CDC. But the number may be much higher, because more than one-half of all adults with low pulmonary function have?COPD without knowing it. (7)
Chronic lower respiratory disease — of which COPD is the biggest component — was the fourth leading cause of death in the United States in 2018, according to data from the?National Center for Health Statistics. (8?PDF).
Certain groups of people are more likely to report having COPD. (7) Among these groups are:
- People between ages 65 and 74, and those 75 and older
- Current or former smokers
- People with a history of asthma
- American Indians/Alaska Natives and multi-racial non-Hispanics
- People who were unemployed, retired, or unable to work
- People with less than a high school education
- People who were divorced, widowed, or separated
Related Conditions of COPD
COPD shares many signs and symptoms with asthma, and there is also overlap in treatment. “[COPD and asthma] are both lung diseases that affect the airways, and they have similar symptoms, including cough, shortness of breath, wheezing, and chest tightening,” says?David A. Beuther, MD, PhD,?a pulmonologist at National Jewish Health in Denver. But the conditions are very different, according to past research. (9)
Asthma is a chronic disease in which the lung’s airways (bronchial tubes) become inflamed and sensitive to environmental triggers, such as dust, smoke, pet dander, or cold air. Most people are diagnosed with asthma in childhood and develop symptoms by age 5. Symptoms of asthma are intermittent, with periods of time when no symptoms exist. Asthma episodes are usually associated with variable airflow obstruction of the lungs, as opposed to the chronic airflow limitation associated with COPD.
People with COPD, on the other hand, usually don’t get diagnosed until they are 40 or older. Smoking is the main risk factor for developing this progressive disease. Symptoms of COPD are persistent.
People with asthma may eventually develop COPD. A?study published in May 2016 in the?New England Journal of Medicine?found a link between persistent childhood asthma and COPD in early adulthood. (10) Researchers followed nearly 700 participants and found that 11 percent suffered from COPD as young adults.
Rheumatoid arthritis has also been linked to a higher risk for COPD in women.
Certain disorders, such as eosinophilic esophagitis (EoE), a chronic disease of the esophagus, may look like COPD or occur along with it.
Resources We Love
There are many resources available to learn more about COPD, its causes, prevention, and treatment. There are also support groups for people who have been diagnosed with the disease or who are caregivers for people with COPD.
Additional reporting by?George Vernadakis.
Editorial Sources and Fact-Checking
- What Is COPD??National Heart, Lung, and Blood Institute.
- Ochs M, Nyengaard JR, Jung A, et al. The Number of Alveoli in the Human Lung.?American Journal of Respiratory and Critical Care Medicine.?January 1, 2004.
- What Is FEV1??Lung Institute. August 13, 2021.
- COPD Causes and Risk Factors.?American Lung Association. March 5, 2021.
- Smoking and COPD.?Centers for Disease Control and Prevention. February 15, 2021.
- Bartolome R,?Celli, B, Cote, C., et al. The Body-Mass Index, Airflow Obstruction, Dyspnea, and Exercise Capacity Index in Chronic Obstructive Pulmonary Disease. The New England Journal of Medicine. March 4, 2004.
- Basics About COPD.?Centers for Disease Control and Prevention. June 9, 2021.
- Mortality in the United States, 2018.?National Center for Health Statistics. January 2020.
- Kim SR, Rhee YK. Overlap Between Asthma and COPD: Where the Two Diseases Converge.?Allergy, Asthma, and Immunology Research. October 2010.
- McGeachie?M, Yates K, Zhou X, et al. Patterns of Growth and Decline in Lung Function in Persistent Childhood Asthma. New England Journal of Medicine. May 12, 2016.