Interstitial Lung Disease & Asbestos

Numerous environmental factors such as asbestos, silica dust, coal dust, cotton dust, and hard metal dusts can cause several forms of interstitial lung disease (ILD). Diseases such as lupus, rheumatoid arthritis, sarcoidosis, and other connective tissue and blood-related disorders can also cause ILD. It is sometimes caused by certain medications and infections, including pneumonia and cytomegalovirus. The form of interstitial lung disease caused by asbestos is called asbestosis. Asbestosis is also known as pulmonary fibrosis and interstitial pneumonitis.

The term interstitial pneumonitis is sometimes confusing because the name is similar to pneumonia. However, this condition is not the same as pneumonia, as it is not caused by an infection. If you have interstitial pneumonitis that was caused by asbestos exposure, your doctor will most likely refer to it by the name asbestosis.

What Is Interstitial Lung Disease?

This disease is an inflammation of the lungs that causes severe scarring. The small airways within your lungs, known as bronchioles, contain clusters of air sacs called alveoli. The alveoli are lined by the interstitium, which is the tissue that supports them. As the inflammation causes thickening and scarring of the interstitium, the air sacs also become thicker and they begin to lose their elasticity. Gradually, the air sacs lose more and more of their capability to put oxygen into the blood and remove carbon dioxide.

The exact mechanism that triggers this scarring process is not clearly understood by scientists. The respiratory system is generally successful in its attempts to clear foreign matter such as dust from the body, but asbestos fibers are especially difficult for the lungs to expel. When the body responds to this type of injury, the repair process often leads to scarring and injury.

Interstitial lung disease from asbestos exposure can take 10 to 30 years to appear from the time of the initial exposure. The good news for people with asbestosis is that the scarring process slows when asbestos exposure ceases. Asbestosis is a progressive disease, meaning scarring continues and symptoms worsen with time. Lung damage caused by asbestos exposure cannot be reversed, though it can be treated to relieve symptoms.

Other Types of Interstitial Lung Disease

There are a number of different types of ILD in addition to asbestosis.

Idiopathic pulmonary fibrosis is the diagnosis given when the cause of fibrosis is unknown (idiopathic). This form of ILD is chronic and progressive, just like asbestosis.

Interstitial pneumonia involves inflammation of the interstitium and is caused by exposure to bacteria, fungi or viruses. It is usually temporary.

Desquamative interstitial pneumonitis is a form of ILD caused by smoking cigarettes.

Hypersensitivity pneumonitis is caused by repeated inhalation of irritants such as dust or mold.

Sarcoidosis is an inflammatory disease that can affect several organs, but usually affects the lungs and lymph nodes.

Symptoms

The symptoms of asbestosis and other interstitial lung diseases are similar to the symptoms of other lung conditions such as COPD and asthma. Unfortunately, by the time the symptoms appear, permanent lung damage has already occurred.

The following symptoms are the most common signs of interstitial lung disease:

  • Becoming short of breath
  • Increasing fatigue during exertion
  • Coughing
  • Chest pain
  • Some patients may experience clubbed fingers
  • Fever
  • Weight loss

Diagnosis

The similarity of ILD symptoms to other lung conditions can often make it difficult for doctors to diagnose the condition. A wide variety of diagnostic tools, including chest X-rays, CT scans, and pulmonary function tests are used to diagnose these diseases.

Chest X-rays are used to rule out other lung conditions such as a collapsed lung or emphysema, but they cannot definitively detect interstitial lung disease. A special computerized tomography (CT) scan called the high-resolution computerized tomography scan (HRCT) can produce highly detailed images of the lungs. HRCTs are very helpful in the diagnosis process.

Doctors may also use pulmonary function tests and exercise tests to determine lung capacity. A short, simple lung capacity test requires a patient to blow into a spirometer, an instrument used to measure lung capacity. A doctor may also evaluate a patient’s lung capacity as they ride a stationary bike or walk on a treadmill.

An oximetry test may be used to monitor oxygen saturation in the blood, which can help track progression of the disease. In advanced cases, blood oxygen levels drop.

Sometimes an echocardiogram is used to determine the amount of pressure being placed around the heart. This test uses sound waves to produce images of the heart and can help visualize where pressure is originating.

Sometimes a tissue sample from the lungs is needed before a definite diagnosis can be made. This can be obtained with a bronchoscopy (transbronchial biopsy) or a bronchoalveolar lavage. For a transbronchial biopsy, the doctor will insert a fiber-optic, flexible tube (bronchoscope) through the mouth and into the lungs to obtain tiny tissue samples.

To obtain a sample through the use of a bronchoalveolar lavage, the doctor will use a bronchoscope to inject a saline solution (salt water) into a section of the lung. The solution, which captures cells from the air sacs, will be immediately suctioned out from the lung and it will then be studied to determine the condition of the lung. A bronchoalveolar lavage is most frequently used to check on the progress of interstitial lung disease in someone who has already been diagnosed with the condition.

Occasionally, a surgical lung biopsy is necessary to obtain a definite diagnosis. The surgeon will make a small cut between the ribs and then insert a tube with a camera on the end (an endoscope) to view the lungs. This is also called video-assisted thoracoscopic surgery or VATS. Through another small incision, the surgeon will insert an instrument to obtain a lung tissue sample.

Treatment

Treatment of interstitial lung disease is aimed at relieving symptoms and preventing complications, such as high blood pressure and heart disease. Oxygen may be prescribed to help a patient who is experiencing shortness of breath. Anti-inflammatory medications such as corticosteroids may be prescribed as well.

Anti-fibrotic medication, such as pirfenidone, can reduce the rate of progression. A class of drugs called tyrosine kinase inhibitors can reduce the progression of fibrosis. One such drug used in the treatment of idiopathic pulmonary fibrosis is called nintedanib.

If the cause is a temporary form of pneumonia, such as pneumonia caused by bacterial infection, a course of antibiotics is prescribed. The type of antibiotic prescribed will depend upon the suspected bacterium causing the infection.

Pulmonary rehabilitation is an option for many people with ILD. However, it is generally underused because few physicians are aware it benefits ILD patients and thus don’t know to recommend the therapy. Pulmonary rehabilitation involves working with a trained therapist who teaches breathing exercises and techniques to improve lung function.

A person with fluid in their lungs may have a doctor drain any excess fluid to help them breathe easier. In rare cases where the lungs are extremely damaged, a lung transplant may be recommended. Fortunately, most people with asbestosis do not require such an extreme treatment.

A doctor will also advise a patient to take precautions to avoid the flu since people with interstitial lung disease are prone to complications from any respiratory infection. Your health provider may suggest a vaccination against the flu and against pneumonia. Regular monitoring of your condition can also help prevent any other complications.

Complications

The complications of asbestosis and other interstitial lung conditions can be life-threatening, since pulmonary hypertension (high blood pressure in the lungs) is a serious problem with these diseases. Pulmonary hypertension occurs when the blood vessels in the alveoli are extremely damaged by scarring. To treat this problem, a patient may receive medicines that will relax or expand the blood vessels. Medications to prevent blood clots (blood thinners) are also used for these conditions.

People with asbestosis may also experience other complications. The Mayo Clinic reports that people with asbestosis who smoke have a greatly increased risk of developing lung cancer. The decision to quit smoking can not only reduce your risk of lung cancer, but also improve your overall lung function and quality of life.

Additional lung damage such as pleural plaques and pleural effusions may also occur if you have asbestosis. Pleural plaques are calcium deposits on the pleura, which is the lining of the lungs. Pleural effusions are abnormal accumulations of fluid between the membranes of the lungs. Although pleural effusions are benign, they do indicate that a person has been exposed to asbestos or another hazardous material. The amount of asbestos exposure necessary to cause asbestosis can also cause malignant mesothelioma (cancer of the pleura).

Prognosis

If detected and treated early, asbestosis may not lead to severe complications. The severity of interstitial lung disease caused by asbestos exposure depends on the length and amount of asbestos exposure, as well as on your overall physical condition and factors such as smoking. People who smoke while exposed to asbestos are especially likely to develop asbestosis. Because asbestosis is not cancer, people can live many years, even decades, with the disease.

Prevention

Since the late 1970s, many regulations have been enacted to protect workers from asbestos exposure. Reducing or eliminating asbestos exposure is the best way to prevent asbestosis. If your home was built before or during the 1980s, it may contain asbestos-containing construction materials. As long as these products are in good condition they are considered safe and not a source of asbestos exposure. Asbestos exposure can occur when asbestos-containing materials are removed from a building. If you need to remove any materials that might contain asbestos, consult an asbestos-abatement professional before you begin the project.

Additional Resources

  1. Medline Plus. (2015, June 22). Asbestosis. Retrieved from http://www.nlm.nih.gov/medlineplus/ency/article/000118.htm
  2. Mayo Clinic. (2015, June 11). Interstitial lung disease. Retrieved from http://www.mayoclinic.com/print/interstitial-lung-disease/DS00592/DSECTION=all&METHOD=print
  3. Medscape. (2011, May 11). Antifibrotic drug promising in idiopathic pulmonary fibrosis. Retrieved from http://www.medscape.com/viewarticle/742827
  4. National Jewish Health. (n.d.). Interstitial lung disease: types. Retrieved from http://www.nationaljewish.org/healthinfo/conditions/ild/types
  5. Ryerson, C.J., Garvey, C., & Collard, H.R. (2010). Pulmonary rehabilitation for interstitial lung disease. Chest; 138(1):240-241. doi:10.1378/chest.10-0550

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