Definition:
Emphysema is a chronic lung condition in which the lungs' natural airspaces "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 to breathe.

Causes
Cigarette smoking is the number one cause of emphysema. A burning cigarette emits over 4,000 different chemicals, many of which are carcinogenic (cancer-causing) or otherwise toxic to living tissue. 5 out of every 6 lung cancer victims are smokers. A huge majority of emphysema sufferers have smoked heavily in the past.

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. People who are carriers of a specific genetic abnormality called "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 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.

Emphysema can also be the results from the exposure to toxins like air pollution, dust, chemical fumes, and irritants.

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 warning sign.

As emphysema progresses, you may experience shortness of breath even when you're resting. This can make normal activities such as eating difficult. This 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 hyperexpanded chest.

Pneumothorax:

Pneumothorax

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 hold. 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 across the alveolar membrane.
chest X-ray or high-resolution CAT scan: A scan is often needed to eliminate the possibility of other medical conditions such as tuberculosis or lung cancer.
oximetry: Measurements of oxygen in the blood as based on a clip 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.

Treatments include:
► 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 in a small percentage of people who have an asthmatic component
    to their emphysema, or with more severe disease and frequent exacerbations.
► Antibiotics: when there is evidence of bacterial infection.
► Exercise: to help to strengthen the muscles that surround the lung. Better-conditioned lungs bring in more air, increasing
    the body's oxygen supply.
► Lung surgery: is often necessary if an expanded lung is pressing against the heart. Lung transplants for emphysema in the
    US have increased from only 2 in 1994 to over 800 in 1999. In a newer type of surgery called lung volume reduction, the
    most diseased (20% to 30%) part of the lung is removed. This allows the remaining lung and muscles to work better,
    improving breathing. The technique is safer, easier, and cheaper than a transplant.
► 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 1-antitrypsin: for treatment of emphysema due to 1-antitrypsin deficiency. This is useless against
    emphysema due to smoking. Gene therapy for this deficiency is being studied.

Vaccinations against influenza and pneumonia, as recommended by your doctor to help avoid respiratory infections.

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