Progressive damage to the lungs, usually caused by smoking, resulting in wheezing and shortness of breath
- More common over the age of 40
- Twice as common in males
- Rarely, due to an abnormal gene inherited from both parents
- Smoking especially, and air pollution are risk factors
In chronic obstructive pulmonary disease (COPD), the airways and tissues of the lungs gradually become damaged over time, causing increasing shortness of breath. Eventually, some people with COPD become so short of breath that they are seriously disabled and unable to carry out even simple daily activities. COPD is twice as common in men and is almost always caused by smoking.
People with COPD usually have two separate lung conditions, chronic bronchitis and emphysema. Either one may be dominant. In chronic bronchitis, the bronchi (airways) become inflamed, congested, and narrowed, and this obstructs the flow of air through them. In emphysema, the alveoli (air sacs) in the lungs become enlarged and damaged, making them less efficient in transferring oxygen from the lungs to the bloodstream. Damage to the lungs caused by bronchitis and emphysema is usually irreversible, although coughing and sputum production may lessen after a person gives up smoking. COPD affects about 1 in 6 people over 40 in the UK, and is a leading cause of death.
What are the causes?
The main cause of both chronic bronchitis and emphysema, and hence of COPD, is smoking. Atmospheric pollution also contributes to the condition. For this reason, COPD is more common in industrialized areas where there is a high percentage of smokers in the population. Occupational exposure to dust, noxious gases, or other lung irritants can worsen existing COPD.
In chronic bronchitis, the linings of the airways of the lungs respond to smoke irritation by becoming thickened, narrowing the passages that carry air into and out of the lungs. Mucus glands in the bronchial linings multiply so that more mucus is produced, and the normal mechanism for clearing the airways and coughing up excess mucus as sputum is impaired. As the disease progresses, retained mucus in the airways easily becomes infected, which may lead to further damage. Repeated infections eventually cause the linings of the airways to become permanently thickened and scarred.
In emphysema, tobacco smoke and other airborne pollutants damage the air sacs. The sacs lose their elasticity, and the lungs become distended. Eventually, the air sacs tear and merge, reducing their total surface area, and air becomes trapped in the dilated sacs. As a result, the amount of oxygen that enters the blood with each breath is reduced. Rarely, the principal cause of emphysema is an inherited condition known as alpha1-antitrypsin deficiency. In such cases, damage occurs whether or not the person smokes, but smoking accelerates the disease.
What are the symptoms?
The symptoms of COPD may take many years to develop. When they do appear, symptoms often occur in this order:
Coughing in the morning that produces sputum.
Coughing throughout the day.
Increasing production of sputum.
Frequent chest infections, especially in the winter months, producing yellow or green sputum.
Wheezing, especially after coughing.
Shortness of breath on mild exertion, becoming progressively worse so that eventually breathlessness occurs even when at rest.
Cold weather and infections such as influenza cause symptoms to worsen. Some people with emphysema develop a barrel-shaped chest as their lungs become distended. Respiratory failure may develop, in which lack of oxygen causes the lips, tongue, fingers, and toes to turn blue. In addition, there may be swelling of the ankles caused by reduced kidney function and chronic heart failure. Some people with severe narrowing of the airways compensate by working hard at breathing and manage to keep their oxygen levels within a normal range when they are at rest. They tend to have a rosy flush to the skin and may be thin because of the amount of energy they need to expend on breathing and because they find it difficult to eat and breathe at the same time. Other people with severe COPD can only manage shallow, ineffective breathing and consequently carbon dioxide builds up in the blood and oxygen levels fall. These people tend to have a blue complexion and tissue swelling in the feet and legs because there is insufficient oxygen reaching the kidneys. Their condition is often compounded by heart failure.
How is it diagnosed?
If you have a history of smoking, the doctor may suspect COPD from your symptoms and a physical examination. He or she may arrange for you to have lung function tests to assess the extent of damage to the lungs. You may have a chest X-ray or CT scanning to exclude other disorders and look for evidence of lung tissue damage. Part of the assessment of lung function may involve taking samples of your blood to check the levels of both oxygen and carbon dioxide (see Measuring blood gases).
If members of your family have developed COPD before the age of 60, you may need a blood test to check the levels of the enzyme alpha1-antitrypsin to look for a deficiency. Your doctor may take a sample of sputum to check for infection, and you may also have electrocardiography (see ECG) or echocardiography to see if your heart is working unusually hard to pump blood through the lungs.
Chronic asthma can produce similar symptoms to those of COPD. If your doctor suspects that you have asthma, you may be prescribed corticosteroid drugs (see Corticosteroids for respiratory disease). If your symptoms improve dramatically, this suggests that you may have asthma rather than COPD.
What can I do?
If you develop COPD and you smoke, giving up permanently is the only action that can slow the progression of COPD. Simply cutting down on your smoking will have little or no effect on the progression of the disorder. Your environment should be kept as free as possible from smoke, pollution, dust, dampness, and cold. If you are overweight, losing the excess weight may help to alleviate breathlessness. Gentle exercise may help to build up your tolerance to exercise but will not improve the function of your lungs.
How might the doctor treat it?
The damage caused by COPD is largely irreversible but there are treatments that may ease the symptoms. You doctor may prescribe an inhaler containing a bronchodilator drug to open up the airways of the lungs by relaxing muscle in the walls of the bronchi. If the bronchodilator drug does not relieve symptoms adequately, your doctor may suggest an inhaled corticosteroid drug in addition to the bronchodilator. For people with severe COPD, it may be recommended that the drugs are taken via a nebulizer (which converts the drugs to a fine mist that is inhaled through a face mask or mouthpiece) rather than by an inhaler.
Some people may be offered continuous home oxygen therapy to relieve shortness of breath. However, this must be used continuously for at least 15 hours each day to help prevent heart failure and improve life expectancy.
If you have swollen ankles, your doctor may prescribe diuretics to reduce the build-up of fluid. Antibiotics may be prescribed if a chest infection develops. You should be immunized against influenza, and you may also be given a vaccine to protect against infection with the bacterium Streptococcus pneumoniae. Both these infections are likely to be serious in people with COPD.
In rare cases of very severe COPD in which the lungs are distended, surgery may be suggested. A procedure called lung volume reduction surgery involves removing damaged areas of lung to allow the remaining areas to inflate and deflate more easily and increase oxygen in the blood. As a last resort for a very small minority of patients who are terminally ill with COPD, a lung transplant may be a possibility.
What is the prognosis?
If your COPD is mild and has been diagnosed at an early stage, you may be able to avoid severe, progressive lung damage by giving up smoking at once. However, most people with COPD do not realize they have the condition until it is well advanced. These people may need to retire from work early and may become inactive and housebound by shortness of breath. Fewer than 1 in 20 people with COPD survives for longer than 10 years after diagnosis.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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