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Thursday, April 7, 2011

What is Interstitial Lung Disease (ILD)

Interstitial Lung Disease (ILD) consists of a variety of diseases that cause a "progressive scarring of lung tissue" that ultimately leads to progressively worsening and irreversible dyspnea and hypoxemia.

Some diseases that fit under this category are:
  1. Interstitial pneumonitis (UIP),
  2. Bronchiolitis obliterans with organizing pneumonia (BOOP),
  3. Lymphocytic interstitial pneumonitis (LIP), and
  4. Desquamative interstitial pneumonitis (DIP).
  5. Pulmonary Fibrosis
  6. Children's Interstitial Lung Disease (chILD)
  7. Asbestosis
  8. Nonspecific interstitial pneumonitis
  9. Respiratory bronchiolitis-associated interstitial lung disease
  10. Familial pulmonary fibrosis
The Mayo Clinic says says that "the walls of the air sacs may become inflamed, and the tissue (interstitium) that lines and supports the sacs becomes increasingly thickened and scarred. Normally, the air sacs are highly elastic, expanding and contracting like small balloons with each breath. But scarring (fibrosis) causes the thin, interstitial tissue to become stiffer and thicker, making the air sacs less flexible. Instead of being soft and elastic, scarred air sacs have the texture of a stiff sponge, which makes it more difficult to breathe and harder for oxygen to enter your bloodstream through the thickened walls."

So what causes ILD?  Generally, something occurs in your lungs that causes an abnormal healing response that results in this permanent scarring. Normally your body will do a good job of repairing damaged tissue, but with ILD the healing process goes "awry," according to the Mayo Clinic, "producing excess scar tissue that increasingly interferes with lung function."

Many environmental substances may be responsible for instigating changes in the lungs that lead to ILD, thus making it difficult to pinpoint the exact cause.  Usually diagnosis is made by a good question and answer session. Possible causes include:
  1. Occupational Hazard: Workers who inhale certain chemicals over a long period of time, such as silica, dust, asbestos fibers, or hard metal dust.
  2. Pollutants: Inhaling some pollutants over a long period of time. This may actually be very difficult to diagnose.
  3. Infections: The healing process as a result of bacterial or viral infections, especially in those with weakened or underdeveloped immune responses, which would include newborn infants. Such infections include pneumonia, fungal infections, histoplasmosis, and parasitic infections.
  4. Radiation: Exposure from radioactive therapy for breast or lung cancer long term can cause damage to the lungs.
  5. Drugs: Chemotherapy drugs, meds used to treat heart arrhythmias, and some antibiotics.
  6. Other lung disorders: Lupus, scleroderma, rheumatoid arthritis, dermatomyositis, polymyositis, Sjogren's syndrome and sarcoidosis all can result in ILD. Some researchers think that gastroesophageal reflux disease (GERD) can also cause ILD and asthma because the acid can destroy lung tissue.
  7. Oxygen: Inhaling greater than 40% oxygen over for a period greater than three hours.
  8. Idiopathic: If the source is unknown, the diagnosis is often idiopathic ILD or idiopathic pulmonary fibrosis. Another similar disease is interstitial pneumonitic, which is often called idiopathic ILD or fibrosis, where the ILD develops not throughout the lung but in patches. These patients will have some normal parts of the lung and some scarred parts of the lung.
  9. Smoking: Does not directly cause ILD, but can increase progression and make the disease worse.
  10. Genetics: Familial pulmonary fibrosis is one type that runs in the family. The gene has not yet been identified.
  11. Age: It usually occurs in adults over 50, although there are some exceptions.
Over time inhaled oxygen is able to make it into the lungs, yet become unable to cross the membrane between the alveolar sacs and the arterioles. This causes shunting that results in a lowered saturation.

Because the lungs become stiff, this results in pulmonary hypertension as a result of the right heart having to work extra hard to pump blood through the lungs. This often results in right heart failure in later stages, and ultimately to left heart failure. Left heart failure, or an enlarged heart, is often a key finding to diagnosing late stage lung disease.

The final complication is respiratory failure.

Diagnosis can be made by any of the following:
  1. X-ray
  2. CT
  3. High resolution computerized tomography
  4. Pulmonary function testing
  5. Bronchoscopy
  6. Bronchiolar lavage
  7. Video assisted thoroscopic surgery
Since there is no cure, treatment is supportive.  Physicians should make sure the patient is first removed from the causative agent, if this hasn't happened already.  Patients who smoke should be encouraged to quit.

Obviously there will be some life changes forced on these patients.  Avoiding the cause, quitting smoking, and learning to comply with a treatment regime can become an arduous and stressful task for anyone.  Many will eventually be forced to stay at home while events they would like to attend are occurring, such as parties where people tend to smoke cigarettes.  They will also have to cope with dyspnea that progressively worsens over time, making even the simplest of activities seem difficult.

While dyspnea is a concern, so too is managing anxiety.

Other possible treatments may include:
  1. Corticosteroids: These help some with ILD, although the side effects can become more debilitating than the benefits. Ideally these should not be used long term.
  2. Mucomyst: This can help break up thick secretions and make it easier to cough up junk.
  3. Anti-fibrotics: These drugs can help reduce the development of scar tissue. Penicillamine, colchicine and interferon gamma-1b are presently in the testing phase and have shown some efficacy in treating ILD.
  4. Oxygen therapy: Most patients with ILD will eventually need supplemental oxygen, and usually this is required 24 hours a day.
  5. Pulmonary Rehabilitation: This is a program to help lung patients stay physically fit in order to live normal active lives. While this does not improve lung function, it is essential.  Staying fit also helps with anxiety. 
  6. Lung Transplantation: May be an option for severe or end stage cases.
  7. Diet: The patient will want to eat a healthy diet. This should include eating small meals, as overeating may cause the diaphragm to push up against the lungs making less room to breathe. It's also recommended not to drink carbonated beverages for the same reason.
  8. BiPAP:  Positive pressure breaths are supplied via a mask to support breathing and keep airways patent and improve oxygenation.  It's usually worn while sleeping, although sometimes patients use it during the day too. 
  9. Anti-anxiety meds: As the disease progresses, it may cause anxiety. This can be treated with medicines like Ativan and Xanax.
  10. Support groups.  Meeting other people with a similar disease condition is always a good way to feel better about your disease.  One way of meeting people is through a pulmonary rehabilitation program. Another is through support groups, many of which can be found online. Another method is to read about your disease and keep up with the latest developments so that you can stay up on the latest developments to assure you are getting the best treatments.
Further Reading:

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