- Related Topics:
- human disease
- human respiratory system
- oxygen therapy
- mechanical ventilation
- lung
- On the Web:
- Harvard Health Publishing - COPD (Nov. 01, 2026)
chronic obstructive pulmonary disease
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What is chronic obstructive pulmonary disease (COPD)?
Chronic obstructive pulmonary disease (COPD) is a progressive respiratory ailment characterized by emphysema and bronchitis. COPD is commonly caused by prolonged exposure to noxious particles, such as tobacco smoke and air pollution.
COPD is characterized pathologically by the destruction of lung tissue, which is replaced by holes characteristic of emphysema, and by a tendency for excessive mucus production in the airway, which gives rise to symptoms of bronchitis. COPD affects tens of millions globally and is a leading cause of death. In 2021, COPD was responsible for approximately 3.5 million deaths.
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How does COPD affect the lungs?
Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disease that occurs when emphysema and chronic bronchitis occur together. Emphysema destroys gas-exchanging tissues in the lungs, causing large air spaces, loss of alveolar walls, and destruction of alveolar capillaries. As a result, the surface area available for oxygen and carbon dioxide exchange is reduced. Similarly, chronic bronchitis causes excessive mucus production in the airway. COPD is characterized pathologically by the destruction of lung tissue, which is replaced by holes characteristic of emphysema.
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What are the two main conditions included in COPD?
Chronic obstructive pulmonary disease (COPD) is a group of conditions causing irreversible respiratory impairment by obstructing airflow in the lungs. COPD commonly includes chronic obstructive bronchitis and pulmonary emphysema, which can occur in varying degrees.
Emphysema is characterized by the destruction of gas-exchanging tissues in the lungs, resulting in abnormally large air spaces. Chronic bronchitis involves long-standing inflammation of the bronchial tree, accompanied by a deep cough and sputum production. Both conditions contribute to shortness of breath during exercise and general disability.
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What happens to the airways and air sacs in someone with COPD?
In chronic obstructive pulmonary disease (COPD), specifically in emphysema, the gas-exchanging tissues of the lungs are destroyed, leading to enlarged air spaces and reduced surface area for oxygen and carbon dioxide exchange. The destruction of alveolar walls and capillaries results in impaired gas transfer.
The loss of elasticity in the alveolar walls causes the lungs to expand, compressing small bronchi and increasing airflow resistance, especially during exhalation. This damage can manifest as centrilobular emphysema, common in smokers, or panacinar emphysema, often linked to alpha-1 antitrypsin deficiency.
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Why does COPD make it difficult for people to breathe out?
Chronic obstructive pulmonary disease (COPD) is a progressive condition affecting millions worldwide, characterized by damage to the airways and reduced airflow in and out of the lungs. COPD includes emphysema, which destroys lung tissue, and chronic bronchitis, which causes excessive mucus production. This combination makes it hard to exhale, leading to increased lung volume and breathlessness.
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How does smoking cause the pathological changes seen in COPD?
Smoking is a primary cause of pathological changes observed in chronic obstructive pulmonary disease (COPD). Cigarettes contain harmful chemicals like poisonous gas carbon monoxide and tar, which can lead to various health risks, including bronchitis and emphysema.
Smoking can cause an increase in the size and number of mucous glands, leading to excessive mucus production and chronic cough. It can also trigger the destruction of alveolar walls, resulting in enlarged air spaces and reduced surface area for gas exchange, which are characteristics of emphysema.
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chronic obstructive pulmonary disease (COPD), progressive respiratory disease characterized by the combination of signs and symptoms of emphysema and bronchitis. It is a common disease, affecting tens of millions of people and causing significant numbers of deaths globally. Sources of noxious particles that can cause COPD include tobacco smoke, air pollution, and the burning of certain fuels in poorly ventilated areas. In rare cases COPD is caused by a genetic defect that results in deficiency of an enzyme known as α1-antitrypsin, which is necessary for the physiological repair of lung tissue. Although primarily a lung disease, it is increasingly recognized that COPD has secondary associations, including muscle weakness and osteoporosis. Identifying and treating these secondary problems via pulmonary rehabilitation (supervised exercise) and other methods may improve the functional status of the lungs.
COPD is distinguished pathologically by the destruction of lung tissue, which is replaced by holes characteristic of emphysema, and by a tendency for excessive mucus production in the airway, which gives rise to symptoms of bronchitis. These pathological characteristics are realized physiologically as difficulty in exhaling (called flow limitation), which causes increased lung volume and manifests as breathlessness. Other early symptoms of the condition include a “smokers cough” and daily sputum production. Coughing up blood is not a feature of COPD and when present raises concern about a second, tobacco-related condition, particularly lung cancer. Patients with COPD are vulnerable to episodic worsening of their condition (called exacerbation). Exacerbations are triggered by infection, either bacterial or viral. Therefore, antibiotics, which work against bacteria, are not always required. Frequent exacerbations, particularly if severe enough to warrant hospital admission, indicate a poor prognosis.
The only therapeutic intervention shown to alter the course of COPD is removal of the noxious trigger, which can be accomplished in most cases by cessation of smoking. Treatments used in the early stages of disease include vaccination against influenza and pneumococcal pneumonia and administration of drugs that widen the airways (i.e., bronchodilators). Inhaled corticosteroids are commonly prescribed, especially for patients with frequent exacerbations. Short courses (typically five days) of oral corticosteroids are given for exacerbations but generally are not used in the routine management of COPD. A six–eight-week course of pulmonary rehabilitation often benefits patients who have symptoms despite inhaler therapy. This should be followed by a community/home maintenance program or by repeat courses every two years.
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In COPD patients with low blood-oxygen levels, the prescription of home oxygen can reduce hospital admission and extend survival but does not alter the progression of lung disease. Some COPD patients do not find oxygen attractive, since they need to use it for 16 hours each day to derive benefit, which leads to further difficulties in mobility. In addition, oxygen is extremely flammable, and the prescription of oxygen for patients who smoke remains controversial because of the risk for explosion. Specialized centres can offer treatments for patients with advanced disease, including noninvasive ventilation and surgical options (i.e., lung transplantation and lung-volume reduction).