Pulmonary fibrosis is scarring in the lungs.
Pulmonary fibrosis develops when the alveoli, tiny air sacs that transfer oxygen to the blood, become damaged and inflamed. The body tries to heal the damage with scars, but these scars collapse the alveoli and make the lungs less elastic. If the cycle of inflammation and scarring continues, the lungs become increasingly unable to deliver oxygen to the blood. Changes in the lungs can also increase the blood pressure in the pulmonary artery.
Pulmonary fibrosis can result from many different lung diseases including sarcoidosis, drug reactions, autoimmune diseases, environmental allergies such as Farmer's lung, and exposure to toxic dusts and gases.
Pulmonary fibrosis that develops without a known cause is called idiopathic pulmonary fibrosis. This disease is equally common in men and women. It is usually diagnosed between the ages of 40 and 60.
Causes and symptoms
The causes and risk factors vary with the underlying disease. They may include genetics, environmental factors, and infections.
The first symptom of pulmonary fibrosis is usually shortness of breath—at first, during exercise, but later also while resting. Patients may also have a dry cough,a rapid heartbeat, or enlargement of the fingertips and ends of the toes. Some people feel tired or have a fever, weight loss, muscle or joint pains. In late stages of the disease, the lack of oxygen in the blood can give the skin and mucus membranes a blue tinge known as cyanosis.
Pulmonary fibrosis is often referred to a lung specialist. Several tests are usually needed to diagnose this disease and determine its cause. They include a physical examination, detailed history of the symptoms, chest x rays, lung function tests, and blood tests, including a measurement of the amount of oxygen in the blood. Computed tomography (CT scan) may give a more detailed picture of the lungs. Bronchoscopy may be done to examine the air passages and analyze the cells found deep in the lungs.
Lung biopsies are necessary to diagnose some diseases. Lung biopsies can be done through a needle inserted into the chest through the skin, during bronchoscopy, or as a surgical procedure under general anesthesia.
The treatment of pulmonary fibrosis depends on the underlying cause. Many diseases are treated by suppressing inflammation with corticosteroids. Stronger immune suppressants such as cyclophosphamide (Cytoxan) or azathioprine (Imuran) may also be tried. Some patients need supplemental oxygen. A lung transplant may be an option for incurable diseases. Approximately 60–80% of patients live for at least two years after the transplant.
There is no good treatment for idiopathic pulmonary fibrosis. Only 10–20% of patients with this disease respond to corticosteroids.
The prognosis depends on the specific disease. Some cases may stop progressing or improve, particularly if the cause can be identified and treated. Others may develop quickly or slowly into end-stage lung disease. The course of idiopathic pulmonary fibrosis is very difficult to predict; however, average survival is approximately five to seven years.
There is no known prevention for idiopathic pulmonary fibrosis.
Some ways to prevent other causes of pulmonary fibrosis are:
- avoid exposure to particle dust such as asbestos, coal dust, and silica
- avoid exposure to chemical fumes
- do not smoke
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Pulmonary Fibrosis Association. P.O. Box 75004, Seattle, WA 98125-0004. (206) 417-0949. <http://pulmonaryfibrosisassn.com>.
Pulmonary Fibrosis Foundation. 1075 Santa Fe Drive, Denver, Colorado 80204. (720) 932-7850. <http://pulmonaryfibrosis.org>.
The American Lung Association. 1740 Broadway, New York. NY 10019. (212) 315-8700. <http://www.lungusa.org>.
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Anna Rovid Spickler, D.V.M., Ph.D.
Alveoli—Tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged with the blood.
Autoimmune disease—A disease that develops when the immune system attacks normal cells or organs.
Bronchoscopy—The examination of the air passages through a flexible or rigid tube inserted into the nostril (or mouth). Sometimes cells are collected by washing the lungs with a small amount of fluid.
End-stage lung disease—The final stages of lung disease, when the lung can no longer keep the blood supplied with oxygen. End-stage lungs in pulmonary fibrosis have large air spaces separated by bands of inflammation and scarring.
Farmer's lung—An allergic reaction to moldy hay, most often seen in farmers, that results in lung disease.
Inflammation—The body's reaction to an irritant, characterized by the accumulation of immune cells, redness, and swelling.
Lung function tests—Tests of how much air the lungs can move in and out, and how quickly and efficiently this can be done. Lung function tests are usually done by breathing into a device that measures air flow.
Mucous membranes—The moist coverings that line the mouth, nose, intestines, and other internal organs.
Pulmonary artery—The blood vessel that delivers blood from the heart to the lungs.
Sarcoidosis—A disease of unknown origin that results in clumps of immune cells and inflammation in organs throughout the body.