Emphysema is a chronic lung condition in which the lungs' natural airspaces, called alveoli, become larger but decrease in number. The tissue surrounding the alveoli loses elasticity so that the airspaces can no longer expand and shrink as usual. This reduces the amount of oxygen transferred by the lungs to the bloodstream, making it more difficult for you to breathe.
Emphysema usually results from exposure to toxins like cigarettes as well as air pollution, dust, chemical fumes, and irritants. Older adults are more likely to be affected and many people who have emphysema are not aware that they have it.
Cigarette smoking is the number one cause of emphysema. Although smoking has decreased in North America since 1964, it's still a major concern among young people. A huge majority of emphysema sufferers have smoked heavily in the past. Smoking is responsible for 80% to 90% of chronic obstructive pulmonary disease (COPD) cases, including emphysema. Smoking is also responsible for at least 85% of all lung cancer cases in Canada. A burning cigarette emits over 4,000 different chemicals, many of which are carcinogenic (cancer-causing) or otherwise toxic to living tissue.
Infections of the respiratory tract can also destroy lung tissue and thus contribute to the development or worsening of emphysema. Likewise, having emphysema increases the likelihood of infection.
Heredity is occasionally a factor in emphysema. Carriers of a specific genetic abnormality called homozygous alpha-1-antitrypsin deficiency are at high risk of developing emphysema. However, it is relatively rare and accounts for less than 1% of cases. If you have alpha-1-antitrypsin deficiency, it's vital not to smoke.
Aging naturally brings changes to the lungs and air sacs even in non-smokers. The loss of elasticity can eventually become severe enough to be classified as emphysema. Air pollution can also irritate the lungs and cause emphysema, although pollution alone is rarely the cause.
Symptoms and Complications
There may be few symptoms at the beginning of the disease. As the air sacs become damaged, shortness of breath with physical activity is usually the first symptom. As emphysema progresses, you may experience shortness of breath even when you're resting. This can make normal activities such as eating difficult, which can lead to a reduced appetite and weight loss. Other symptoms include chest tightness, fatigue, and chronic cough.
As the air sacs become more stretched, air gets trapped in pockets called bullae that form in the lungs. This can produce a characteristic "barrel chest," which is the shape of the hyper-expanded chest.
Chronic lung damage prevents the heart from circulating blood normally. Lung damage can cause pressure elevations in the part of the heart that moves blood through the lungs. This is called pulmonary hypertension and is suspected when people with emphysema develop leg swelling, abdominal bloating, or prominent pulsations in the veins in the neck.
Bullae can rupture outside the lung into the pleural space (the space that surrounds the lung). As the air accumulates outside the lung, it may result in a life-threatening condition called pneumothorax. The body will also attempt to compensate for the low oxygen level by increasing the number of red blood cells (secondary polycythemia). Sometimes, the increase in red blood cells can be so severe that it causes blood clots.
Making the Diagnosis
A doctor who suspects emphysema will likely want to know your history and will also perform lung function tests. The tests may include:
- spirometry: The forced expiratory volume exhaled after one second (FEV1) test measures the amount of air you can exhale in one second. The forced vital capacity (FVC) test measures the total amount of air that the lungs can expel. These are the most common measures of lung function.
- pulmonary function tests: These include spirometry, but also measurements of lung size, oxygenation, and gas diffusion testing.
- chest X-ray or high-resolution CAT scan: A scan is often needed to eliminate the possibility of other medical conditions, such as lung fibrosis or other lung diseases.
- oximetry: Measurement of oxygen in the blood is tested by a small device that clips on the finger, toe, or ear.
- arterial blood gases: Blood tests provide relevant information on the amount of oxygen and carbon dioxide in your bloodstream.
Treatment and Prevention
The first treatment for emphysema is to stop smoking. Your lungs won't repair themselves, but at least further damage can be slowed. There's still no way to repair emphysematous lung tissue in humans, although researchers are studying the use of retinoic acid (a vitamin A derivative) for this purpose.
- Oxygen therapy, which is used to increase the percentage of oxygen that the body receives on each breath. Machines that concentrate oxygen may be used in the home.
- Bronchodilators such as beta-agonists and anticholinergic medications, which help to relax and open the airways.
- Corticosteroids that reduce inflammation may be used, and these may prevent flare-ups that require hospitalization.
- Antibiotics when there is evidence of infection.
- Exercise can help strengthen leg muscles so that less demand is placed on the lungs with activity.
- Lung surgery,or a lung transplant, can be lifesaving in the small number of people who are candidates for it. In a newer type of surgery called lung volume reduction, the most diseased part of the lung (20% to 30%) is removed. This allows the remaining lung and muscles to work better, improving breathing. Research is ongoing to determine if the same benefit can be achieved by removing the emphysematous lung tissue non-surgically (i.e., by using valves or glue).
- Surgery for pneumothorax is done by permanently joining the separated portion of lung wall and chest wall. An irritant such as talc is blown into the gap, forming scar tissue that binds the two surfaces.
- Purified human alpha-1-antitrypsin for treatment of emphysema due to alpha-1-antitrypsin deficiency.
- Vaccinations against influenza and pneumonia, as recommended by your doctor to help avoid respiratory infections. This doesn't treat the emphysema but can prevent flare-ups.
For the vast majority of people with emphysema, the best way to prevent it and slow it down is to not smoke. This outweighs all other considerations.
Following these tips can help protect your lungs if you have emphysema:
- Don't smoke.
- Avoid secondhand smoke.
- Avoid air pollution as much as possible.
- Use air conditioning with a filter and humidity control.
- Avoid allergic "triggers" that can aggravate emphysema if asthma coexists.
- Avoid high altitudes.
- Wash your hands and brush your teeth frequently to avoid infections.
- Drink plenty of fluids to reduce the buildup of thick mucous in your air passages.