COPD
Meaning of COPD: Two overlapping processes sit under one abbreviation: inflamed, narrowed airways and air sacs whose walls have broken down.
Definition of COPD
COPD, short for chronic obstructive pulmonary disease, is a long term lung condition in which air moves out of the lungs more slowly than it should and never fully returns to normal. It develops over years, usually after prolonged exposure to tobacco smoke or other inhaled irritants, and it makes breathing steadily harder as the obstruction worsens.
What are the two processes behind it?
COPD is an umbrella term rather than a single lesion, and most people have some of each process below.
| Process | What happens in the lung | What it produces |
|---|---|---|
| Chronic bronchitis | The lining of the bronchi is persistently inflamed, mucus glands enlarge and the airway walls thicken and narrow | A cough that brings up sputum on most days, recurring over successive years |
| Emphysema | The walls between neighboring alveoli break down, merging many small air sacs into fewer large ones and destroying the elastic recoil that empties the lung | Less surface for gas exchange, and air trapped in the chest on breathing out |
The proportions differ from person to person, which is why two people carrying the same label can look quite different.
What causes the damage?
Long term cigarette smoking is the dominant cause where smoking is common, but it is not the only one. Smoke from indoor cooking and heating fuel, workplace dust, fumes and vapors, and heavy outdoor air pollution all produce the same pattern of injury. A small number of cases trace to alpha-1 antitrypsin deficiency, an inherited shortage of a protein that normally protects lung tissue from the enzymes released by inflammatory cells, and these cases tend to appear at a younger age than usual. Lungs that grew poorly in childhood, or were damaged by severe early infection, start from a lower reserve and reach the same threshold sooner.
Why is the obstruction called irreversible?
Airway narrowing in asthma opens up substantially with a bronchodilator; in COPD it does not, and that persistence is what breathing tests look for. Because destroyed alveolar walls and remodeled airways do not regrow, assessment centers on how much function remains and how quickly it is changing rather than on undoing damage. Symptoms are also punctuated by exacerbations, periods of days to weeks when cough, sputum and breathlessness worsen sharply, often triggered by infection. People with COPD carry a raised risk of lung cancer as well, partly because the two share the same leading exposure.
Also known as
Used in a sentence
The patient's history of long term smoking and progressive shortness of breath led to a workup for COPD.
Good to know
COPD is an umbrella term that includes chronic bronchitis and emphysema, and a given person with COPD may have features of one, the other, or both processes together.