COPD stands for Chronic Obstructive Pulmonary Disease, a condition characterized by an obstruction of the airways that interferes with normal breathing. Cigarette smoke is the main cause of this disease.
Chronic bronchitis and emphysema are the two most common conditions of COPD:
- chronic bronchitis is the inflammation of the tissue lining the bronchi, i.e. the structures that are responsible for transporting air to and from the lungs.
- emphysema is a degeneration of the structure of the pulmonary alveoli, which are gradually destroyed. Lung damage caused by COPD is not reversible, but treatment can help control symptoms and slow down disease progression.
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Symptoms
Symptoms of COPD often don’t appear until significant lung damage has occurred, and the damage usually worsens over time. For chronic bronchitis, the main symptom is a persistent cough for at least three months a year for two consecutive years.
Other signs and symptoms of COPD may include:
- Dyspnoea, especially during physical activities
- Wheezing
- Chest tightness
- Excessive secretion of mucus in the airways
- A chronic cough that produces abundant and persistent mucus
- Blueness of the lips or fingernail beds (cyanosis)
- Frequent respiratory tract infections
- Asthenia
- Weight loss
Causes
Emphysema
The main cause of COPD is tobacco smoking. However, in the developing countries, COPD often occurs in women exposed to fumes from burning fuel for cooking and heating in poorly ventilated homes. Around 20% of chronic smokers will develop COPD. Some smokers develop less common lung conditions. These may be misdiagnosed as having COPD until a more thorough evaluation is performed.
Air travels down the trachea and into the lungs through two large tubes (bronchi). Inside the lungs, these tubes divide like the branches of a tree, to form smaller tubes (bronchioles) that end in clusters of tiny air sacs (alveoli). Air sacs have very thin walls full of tiny blood vessels (capillaries). Inhaled oxygen passes into these blood vessels and enters the bloodstream. At the same time, carbon dioxide, a gas that is a waste product of metabolism, is released in the alveoli and exhaled.
The mechanism through which the lungs inhale and exhale air is based partly on the natural elasticity of the airways. COPD causes them to lose their physiological elasticity and collapse, reducing their lumen and therefore reducing the volume of air exchanges. This causes a more or less severe respiratory insufficiency.
Causes of airway obstruction:
- Emphysema. This lung disease causes destruction of the fragile walls and elastic fibres of the alveoli. Small airways collapse when you exhale, reducing airflow in the lungs.
- Chronic bronchitis. In this condition, bronchial tubes become inflamed and narrowed and the lungs produce more mucus, which can further block the narrowed bronchi. The body reacts by developing a chronic cough with the aim of trying to clear the mucus obstructing the bronchial lumen.
- Cigarette smoke and other irritants In the vast majority of cases, the lung damage that leads to COPD is caused by long-term cigarette smoking. But there are likely other factors at play in the development of COPD, such as a genetic susceptibility to the disease, because only about 20 percent of smokers develops COPD.
Other irritants can cause COPD, including cigar smoke, secondhand smoke, pipe smoke, air pollution and workplace exposure to dust, smoke or fumes.
- Alpha-1-antitrypsin deficiency
In about 1 percent of people with COPD, the disease results from a genetic disorder that causes low levels of a protein called alpha-1-antitrypsin. Alpha-1-antitrypsin (AAt) is made in the liver and secreted into the bloodstream to help protect the lungs. Alpha-1-antitrypsin deficiency can affect the liver as well as the lungs. Damage to the lung can occur in infants and children, not only adults with long smoking histories.
Risk factors
Risk factors for COPD include:
- Exposure to cigarette smoke. The most significant risk factor for COPD is long-term cigarette smoking. The more years you smoke and the more packs you smoke, the greater your risk. Pipe smokers, cigar smokers and marijuana smokers also may be at risk, as well as people exposed to large amounts of secondhand smoke.
- People with asthma who smoke. The combination of asthma, a chronic inflammatory airway disease, and smoking increases the risk of COPD even more.
- Exposure to dusts and chemicals at work. Long-term exposure to chemical fumes, vapours and dusts in the workplace can irritate and inflame your lungs, therefore increasing the risk of COPD.
- Age. COPD develops slowly over years; in the vast majority of cases, symptoms appear after the age of 35 – 40.
- Genetics. A rare genetic disorder known as alpha-1-antitrypsin deficiency is the cause of some cases of COPD. Other genetic factors likely make certain smokers more susceptible to the disease.
Complications
Complications of COPD include:
- Respiratory tract infections. People with COPD are more likely to catch colds, the flu and pneumonia. Any respiratory infection can make it much more difficult to breathe for people suffering with COPD, and it could cause further damage to lung tissue. An annual flu vaccination and regular vaccination against pneumococcal pneumonia can prevent some of these infections.
- Arterial hypertension. COPD may cause high blood pressure in the arteries that bring blood to the lungs (pulmonary hypertension).
- Cardiac issues. For reasons that aren’t fully understood, COPD can increase your risk of heart disease, including heart attack.
- Lung cancer. Smokers with chronic bronchitis have a higher risk of developing lung cancer compared to smokers who don’t suffer with chronic bronchitis.
Depression. Difficulty breathing can keep you from doing activities that you enjoy, therefore compromising the quality of life.
Tests and diagnosis
Spirometry
COPD is often misdiagnosed. Former smokers are often told that they have COPD, when in reality they may have other respiratory issues; in the same way, many people who suffer with COPD are not identified as such, so that the diagnosis is delayed to a much later stage of the disease.
If you have symptoms of COPD and a history of exposure to lung irritants, particularly to cigarette smoke, your doctor may recommend these tests:
- Pulmonary function test. Spirometry is the most common lung function test. During this test, you’ll be asked to blow into a large tube connected to a small machine called a spirometer. This machine measures how much air your lungs can hold and how fast you can blow the air out of your lungs. Spirometry can detect COPD even before you have symptoms of the disease. It can also be used to track the progression of disease and to monitor how well treatment is working for patients suffering with COPD.
- Chest radiography. A chest X-ray can show emphysema, one of the main causes of COPD. An X-ray can also rule out other lung problems or heart failure.
- CT scan. A lung CT scan can help detect emphysema and help determine if you might benefit from surgery for COPD. CT scans can also be used to screen for lung cancer, which is more common in people suffering with COPD.
- Arterial blood gas analysis. This test measures the efficacy of gas exchanges between the blood and the air contained by the alveoli.
