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Interstitial Lung Disease (Pulmonary Fibrosis)

Illustration of  the  anatomy of the respiratory system, adult
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What are interstitial lung diseases?

Interstitial lung disease, or ILD, is a common term that includes more than 100 chronic lung disorders, which may be:

  • Nonmalignant (noncancerous)

  • Noninfectious

Interstitial lung diseases are named after the tissue between the air sacs of the lungs called the interstitium--the tissue affected by fibrosis (scarring).

Interstitial lung diseases may also be called interstitial pulmonary fibrosis or pulmonary fibrosis.

The symptoms and course of these diseases may vary from person to person, but the common link between the many forms of ILD is that they all begin with an inflammation.

  • Bronchiolitis. Inflammation that involves the bronchioles (small airways).

  • Alveolitis. Inflammation that involves the alveoli (air sacs).

  • Vasculitis. Inflammation that involves the small blood vessels (capillaries).

Most interstitial lung diseases are diagnosed as pneumoconiosis, a drug-induced disease, or hypersensitivity pneumonitis. The other types are:

  • Sarcoidosis

  • Idiopathic pulmonary fibrosis (idiopathic means a disease for which a cause is unknown)

  • Bronchiolitis obliterans

  • Histiocytosis X

  • Chronic eosinophilic pneumonia

  • Collagen vascular disease

  • Granulomatous vasculitis

  • Goodpasture's syndrome

  • Pulmonary alveolar proteinosis

How does interstitial lung disease occur?

In interstitial lung disease, the lung is affected in three ways:

  1. Lung tissue is damaged in some known or unknown way.

  2. The walls of the air sacs in the lungs become inflamed.

  3. Scarring (fibrosis) begins in the interstitium.

Fibrosis results in permanent loss of that tissue's ability to breathe and carry oxygen. Air sacs, as well as the lung tissue between and surrounding the air sacs, and the lung capillaries, are destroyed by the formation of scar tissue.

The diseases may run a gradual course or a rapid course. People with ILD may notice variation in symptoms--from very mild, to moderate, to very severe. The condition may remain the same for long periods of time or it may change quickly. The course of ILDs is unpredictable. If they progress, the lung tissue thickens and becomes stiff. The work of breathing then becomes more difficult and demanding. Some of the diseases improve with medication if treated when inflammation occurs. Some people may need oxygen therapy as part of their treatment.

What causes interstitial lung diseases?

The cause of interstitial lung disease is not known; however, a major contributing factor is thought to be inhaling environmental or occupational pollutants, such as inorganic or organic dusts.

Other contributing factors include:

  • Sarcoidosis

  • Certain drugs or medications

  • Radiation

  • Connective tissue or collagen diseases

  • Family history

What are the symptoms of interstitial lung diseases?

The following are the most common symptoms for interstitial lung diseases. However, each individual may experience symptoms differently. Symptoms may include:

  • Shortness of breath, especially with exertion

  • Fatigue and weakness

  • Loss of appetite

  • Loss of weight

  • Dry cough that does not produce phlegm

  • Discomfort in the chest

  • Labored breathing

  • Hemorrhage in the lungs

The symptoms of interstitial lung diseases may resemble other lung conditions or medical problems. Consult your doctor for a diagnosis.

How are interstitial lungs diseases diagnosed?

In addition to a complete medical history and physical examination, the doctor may also request the following tests:

  • Pulmonary function tests. Diagnostic tests that help to measure the lungs' ability to move air into and out of the lungs effectively. The tests are usually performed with special machines into which the person must breathe. Two types of pulmonary function tests are:

    • Spirometry. A spirometer is a device used by your doctor to assess lung function. Spirometry, the evaluation of lung function with a spirometer, is one of the simplest, most common pulmonary function tests and may be necessary for any or all of the following reasons:

      • To determine how well the lungs receive, hold, and utilize air

      • To monitor a lung disease

      • To monitor the effectiveness of treatment

      • To determine the severity of a lung disease

      • To determine whether the lung disease is restrictive (decreased airflow) or obstructive (disruption of airflow)

    • Peak flow monitoring (PFM). A device used to measure the fastest speed at which a person can blow air out of the lungs. During an asthma or other respiratory flare-up, the large airways in the lungs slowly begin to narrow. This will slow the speed of air leaving the lungs and can be measured by a PFM. This measurement is very important in evaluating how well or how poorly the disease is being controlled.

  • Chest X-rays. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.

  • Blood tests. Arterial blood gas to analyze the amount of carbon dioxide and oxygen in the blood.

  • High-resolution computed tomography scan (also called an HRCT, CT, or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce sharper and more detailed horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. HRCT scans are more detailed than general X-rays.

  • Bronchoscopy. The examination of the bronchi (the main airways of the lungs) using a flexible tube (bronchoscope). Bronchoscopy helps to evaluate and diagnose lung problems, assess blockages, obtain samples of tissue and/or fluid, and/or to help remove a foreign body. Bronchoscopy may include a biopsy or bronchoalveolar lavage.

  • Bronchoalveolar lavage. A medical procedure to remove cells from the lower respiratory tract to help identify inflammation and exclude certain causes.

  • Lung biopsy. A procedure to remove tissue from the lung for examination in the pathology laboratory.

What is the treatment for interstitial lung diseases?

Specific treatment will be determined by your doctor based on:

  • Your age, overall health, and medical history

  • Extent of the disease

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Treatments may include:

  • Oral medications, including corticosteroids and cyclophosphamide (Cytoxan)

  • Pulmonary rehabilitation

  • Oxygen supplementation from portable containers

  • Lung transplantation