Pulmonary fibrosis refers to several conditions which cause scarring of the lung and destroys its abilitie to extract oxygen from the air. Fibrosis can damage the functional unit of the lung, the alveolus, and can thicken the spaces between the alveoli called the interstitial spaces. This makes it more difficult for oxygen to diffuse from the alveolus to the capillaries of the lung and be transported to the body. Similarly carbon dioxide elimination is less effective. The lungs become stiffer and the volumes of the lungs decrease. This process can be slowly progressive or, rarely, may occur rapidly over a period of months.
Pulmonary fibrosis may be detected on a plain chest x-ray but is seen in more detail on a CAT scan of the chest. Pulmonary function tests will show a restrictive pattern with a reduction in the total lung capacity and diffusion capacity. At times, the oxygenation of the blood is affected.
Pulmonary fibrosis usually presents with unexplained shortness of breath and sometimes a dry cough. It is associated with an abnormal chest x-ray, sometimes confused with congestive heart failure. On physical examination, dry crackling noises called fibrotic rales can be heard over the chest when listening with a stethoscope.
The cause of pulmonary fibrosis can vary considerably. A key distinction is whether the fibrosis is secondary to another more generalized process such as rheumatoid arthritis or lupus, or alternatively is idiopathic. Idiopathic pulmonary fibrosis is often triggered by a viral infection but apparently results in uncontrolled deposition of collagen (scar tissue) in the interstitium of the lung, rather than healing as typically occurs. Idiopathic pulmonary fibrosis (IPF) is more difficult to treat. It is important to note that fibrosis cannot be “undone” but treatment can prevent progression of disease if caught early. The initial evaluation of fibrosis includes a chest x-ray, high-resolution CT of the chest, and complete pulmonary function testing. Blood tests to exclude autoimmune diseases such as lupus are commonly performed, since treatment of the underlying disorder will often prevent progression of the fibrosis. Bronchoscopy with or without biopsy of the lung and performance of ronchoalveolar lavage to analyze the cellular composition retrieved from the alveolar spaces can be helpful in forming a therapeutic plan. Open lung biopsy to assess the severity of the fibrosis is sometimes recommended.
Treatment options for pulmonary fibrosis vary considerably depending on the cause of the scarring and the stage of the disease. Generally antiinflammatory drugs such as prednisone, which decrease the ongoing inflammation leading to fibrosis, are recommended. Other drugs such as Imuran, which is a chemotherapeutic agent that decreases the need for corticosteroids and prevents inflammation, may be recommended. Over-the-counter medication such as NAC (N-acetylcysteine) has an antiinflammatory and antioxidant effect and is sometimes prescribed. There are several experimental protocols available through the Pulmonary Fibrosis Clinic at the University of Alabama in Birmingham that are available. In very severe cases, lung transplantation is considered.