October 31, 2014
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Pulmonary Fibrosis

(Interstitial Pulmonary Fibrosis, Lung Fibrosis)

The Facts on Pulmonary Fibrosis

Fibrosis refers to scar tissue that has replaced healthy tissue. This is what happens in the lungs of people with pulmonary fibrosis. Inflammation (swelling) in the lungs usually happens before or at the same time as the formation of scar tissues.

There are several substances known to cause lung fibrosis, but people often develop lung fibrosis even when there is no apparent cause. When the cause is unknown, it's called idiopathic.

Idiopathic pulmonary fibrosis is a serious condition whose cause is not well understood. Another condition very similar to idiopathic pulmonary fibrosis can happen in some people with certain diseases, especially autoimmune diseases like systemic lupus erythematosis or scleroderma. Whether this other condition is the same thing as idiopathic pulmonary fibrosis or slightly different is unknown.

When pulmonary fibrosis is idiopathic, it most often occurs in people 50 years of age and older, but people of any age can develop it. Pulmonary fibrosis can be detected at an early stage or late stage but usually gets worse with time. Sometimes it progresses slowly but it can also progress quickly over just a few years or even months.

Causes of Pulmonary Fibrosis

There are many potential causes of pulmonary fibrosis, such as:

  • rheumatoid arthritis
  • scleroderma
  • lupus
  • mineral dusts - coal, silicon, asbestos (asbestosis), metals
  • poisonous industrial gases such as chlorine and sulphur dioxide
  • radiation treatment to the chest
  • poisons - particularly paraquat
  • medications (e.g., nitrofurantoin, amiodarone, bleomycin, cyclophosphamide methotrexate)

The cause of pulmonary fibrosis, especially when it is idiopathic, is poorly understood. It probably involves deregulation of the immune system in the lungs, but some experts still think it might be caused by an unknown environmental exposure, or even an unusual infection.

A few families are particularly affected by idiopathic pulmonary fibrosis, which may be categorized into two forms - an environmental form and a rarer genetic form. Pulmonary fibrosis is more likely caused by environmental factors in genetically susceptible people. These people have immune systems that overreact in the presence of particular irritants or organisms. This would be typical of autoimmune disease.

The mechanism of the disease is as follows: The lungs become inflamed, usually for no clear reason. White blood cells and liquid fill the alveoli (the lung's tiny air pockets where oxygen is transferred to the blood). If the liquid remains for long enough, blood-clotting agents solidify, leaving scars that can interfere with the function of the alveoli.

The blood vessels of the lungs are separated from the air pockets by walls called interstitia. The interstitium allows oxygen to reach the blood, and carbon dioxide from the blood to pass into the lungs to be breathed out. Fibrosis damages this membrane, thickening it and thus reducing the lungs' ability to add oxygen and remove carbon dioxide from the blood.





Symptoms and Complications of Pulmonary Fibrosis

For the majority of people, the symptoms of pulmonary fibrosis come on slowly over the course of months to years, but for some people the symptoms can develop more rapidly.

Most people with pulmonary fibrosis first see their doctor about increasing shortness of breath during exercise. Some also have a cough. These are often the only symptoms of early pulmonary fibrosis, but you might also feel one or more of the following symptoms:

  • loss of stamina
  • loss of appetite
  • fatigue
  • weight loss
  • diffuse chest pain

Later on, symptoms can include:

  • shortness of breath without exercise - eating, talking, or just resting
  • cyanosis (blue lips, nail beds, and sometimes skin due to lack of oxygen in the tissue)
  • clubbing of the fingers (enlarged fingertips)

Pulmonary fibrosis can lead to several severe complications. Because the lungs don't take in oxygen as well, low blood oxygen levels (hypoxemia) can develop. Lack of oxygen can affect the entire body.

Another complication of pulmonary fibrosis is pulmonary hypertension (high blood pressure in the arteries of the lungs). Scar tissue in the lungs can make it more difficult for blood to flow through them. The increased pressure makes the heart work harder and leads to a weakened and enlarged heart, reducing its pumping efficiency and producing heart failure. This is suspected when people develop fluid accumulations in the abdomen, leg swelling, or prominent pulsations in neck veins.

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