Smoking: Cigarette smoke is by far the most common cause of emphysema. The damage begins when tobacco smoke temporarily paralyzes the microscopic hairs (cilia) that line the bronchial tubes. Normally, these hairs sweep irritants and germs out of the airways. But when smoke interferes with this sweeping movement, irritants remain in the bronchial tubes and infiltrate the alveoli, inflaming the tissue and eventually breaking down elastic fibers. Shortness of breath (dyspnea) is caused by the lungs being over inflated trying to get more oxygen to the tissues.
Genetic protein deficiency: In a small percentage of people, emphysema results from low levels of a protein called alpha-1-antitrypsin (AAt), which protects the elastic structures in the lungs from the destructive effects of certain enzymes. A lack of AAt can lead to progressive lung damage that eventually results in emphysema.
Pulmonary function tests (PFTs): These noninvasive tests can detect emphysema before symptoms are seen. They measure how much air the lungs can hold and the flow of air in and out of the lungs. They can also measure the amount of oxygen and carbon dioxide exchanged in the lungs. They include a spirometry test and lung volume test.
In a spirometry test, a person breathes into mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that is breathed in and out over a specified time. Some of the test measurements are obtained by normal, quiet breathing, and other tests require forced inhalation or exhalation after a deep breath.
Lung volume measurement detects restrictive lung diseases. In this set of diseases, a person cannot inhale a normal volume of air. Restrictive lung diseases may be caused by inflammation or scarring of the lung tissue (interstitial lung disease) or by abnormalities of the muscles or skeleton of the chest wall.
Lung volume measurement can be performed in two ways. The most accurate way is for an individual to sit in a body plethysmograph (a sealed, transparent box that resembles a telephone booth) while breathing in and out a mouthpiece. Changes in pressure inside the box allow determination of the lung volume. Lung volume can also be measured when a individual breathes nitrogen or helium gas through a tube for a specified period of time. The concentration of the gas in a chamber attached to the tube is measured, allowing estimation of the lung volume.
Chest X-ray: A chest X-ray can help rule out other lung problems (such as lung cancer) rather than to diagnose emphysema. Even in the advanced stages of emphysema, chest X-rays are often normal.
Blood tests: Arterial blood gases (ABGs) measure how well the lungs transfer oxygen to the bloodstream and how effectively they remove carbon dioxide from the bloodstream. A blood test for the alpha-1-antitrypsin (AAt) gene, which is found in some individuals with emphysema, may also be used.
Pulse oximetry: This test involves use of a small device that attaches to the fingertip to measure the amount of oxygen in the blood. To help determine whether the individual needs supplemental oxygen, the test may be performed at rest, during exercise and overnight.
Sputum examination: Analysis of cells in sputum (matter coughed up from the respiratory tract) can help determine the cause of some lung problems. If bacteria are present, there is infection. Blood may also be present in sputum.
Computerized tomography (CT) scan: A CT scan allows a healthcare professional to see the organs in two-dimensional images or "slices." Split-second computer processing creates these images as a series of very thin X-ray beams are passed through the body. A CT scan can detect emphysema sooner than an X-ray can, but it cannot assess the severity of emphysema as accurately as a pulmonary function test.
signs and symptoms
Shortness of breath: Shortness of breath (dyspnea), especially during activity, is one of the earliest symptoms of emphysema. As the disease progresses, shortness of breath becomes constant, even during rest.
Fatigue: Shortness of breath causes a reduced capacity for physical activity, becoming worse as the disease progresses. An individual is likely to feel tired both because it is more difficult to breathe and because the body is getting less oxygen.
Lowered immunity: In addition, individuals may suffer from frequent colds accompanied by coughing.
Others: Other symptoms include distress resulting from the inability to get enough air, wheezing, chronic mucus production, weight loss, exhaling through pursed (puckered) lips or grunting before exhaling, needing to lean forward to breathe while sitting, and anxiety (nervousness) and/or depression. Individuals with emphysema are often thin and have very pink skin. Individuals with advanced disease may have the characteristic barrel chests from the increase in lung size.
Individuals with emphysema have a higher death rate than those with normal lung function. Causes of death include cancer, stroke (lack of blood flow and oxygen to the brain), respiratory failure, lung infections such as pneumonia and influenza, and heart attack. Eventually, severe shortness of breath will limit the person's normal daily activities.
Individuals who continue to smoke will have worsening shortness of breath. They may have panic attacks when they are unable to get enough air in and out. People with advanced emphysema are often incapacitated. They are short of breath even when confined to a chair or bed.
Smoking: The single greatest risk factor for emphysema is smoking. Emphysema is most likely to develop in cigarette smokers, but cigar and pipe smokers and marijuana smokers also are susceptible, and the risk for all types of smokers increases with the number of years and amount smoked. Men are affected more often than women are, but this statistic is changing as more women take up smoking.
Age: Although the lung damage that occurs in emphysema develops gradually, most people with tobacco-related emphysema begin to experience symptoms of the disease between the ages of 50-60.
Exposure to secondhand smoke: Secondhand smoke, also known as passive or environmental tobacco smoke, is smoke that is inadvertently inhaled from someone else's cigarette, pipe or cigar.
Pollution and chemical exposure: An individual breathing fumes from certain chemicals such as chlorine or pesticides, dust from grain, cotton, wood, or working around toxic fumes, is more likely to develop emphysema. The risk is even greater if the person smokes. Breathing indoor pollutants such as fumes from heating fuel as well as outdoor pollutants such as car exhaust, increases the risk of emphysema.
Heredity: A rare, inherited deficiency of the protein, alpha-1-antitrypsin (AAt), can cause emphysema, especially before age 50, and even earlier if the individual smokes.
Connective tissue disorders: Some conditions that affect connective tissue (provides body framework and support) are associated with emphysema. These conditions include cutis laxa (a rare disease that causes premature aging) and Marfan syndrome (a disorder that affects many different organs, especially the heart, eyes, skeleton and lungs).