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Wednesday, December 17, 2014
Pulmonary fibrosis means scarring of the lung. Many diseases can cause pulmonary fibrosis including infections, radiation therapy, certain medications, and some diseases such as rheumatoid arthritis, scleroderma, mixed connective tissue disease, and systemic lupus erythematosus. The most common cause of pulmonary fibrosis is idiopathic pulmonary fibrosis (pulmonary fibrosis of unknown cause).
In some types of pulmonary fibrosis, the process starts with inflammation. Evidence suggests that inflammation can contribute to the scarring process. Once scarring sets in, medications can do very little for the disease. The approach in the medical treatment of pulmonary fibrosis is to stop the inflammation in hopes of stopping future scarring, although new medications are focused on attacking the cells producing the scar.
In other types of pulmonary fibrosis (such as idiopathic pulmonary fibrosis), there may be little inflammation before scarring develops. The most common symptoms of pulmonary fibrosis are shortness of breath, particularly with activities, and cough. The fibrosis is usually first suspected by your physician when he or she hears "crackles" when listening to your lungs (sounds similar to Velcro being torn apart) or when he or she sees scarring on a chest x-ray.
To confirm a diagnosis of pulmonary fibrosis, a high-resolution chest CT scan is often performed because it can sometimes determine the cause of the fibrosis. It can also lead the lung specialist to the best part of the lung for biopsy.
The next step is frequently a bronchoscopy with bronchoalveolar lavage and sometimes with transbronchial biopsy. Bronchoalveolar lavage is a technique in which the lung is rinsed out. The rinsings are then analyzed in the laboratory for the type of inflammation present, evidence of cancer cells, and evidence of certain infections. A transbronchial biopsy is performed through the bronchoscope and yields small, pinhead-sized pieces of lung, which can be looked at under the microscope to determine the cause of fibrosis. Because these biopsies are small, they do not permit a confident diagnosis in all types of pulmonary fibrosis.
All in all, high-resolution CAT scan and bronchoscopy will yield a firm diagnosis in about half of cases. If the diagnosis remains uncertain, then an open lung biopsy is often performed. This is done by being admitted to the hospital, being taken to the operating room, and being put under general anesthesia. A surgeon makes an incision in the chest to remove thumbnail-sized pieces of lung for microscopic analysis.
To determine the stage of the pulmonary fibrosis, pulmonary function studies and sometimes pulmonary exercise tests are performed to determine how severely the fibrosis is affecting your lung function. Pulmonary function studies are frequently performed periodically to determine whether the lungs are responding to treatment.
Pulmonary exercise tests can be done either with a 6-minute walk test (when the patient walks in a hallway as fast as possible for 6 minutes) or with a cardiopulmonary exercise test (when a patient rides a stationary bicycle and various breathing measurements are made during exercise).
The treatment of pulmonary fibrosis varies depending on the cause of the condition. For the form of idiopathic pulmonary fibrosis called "usual interstitial pneumonitis" (the most severe form of pulmonary fibrosis), options can include no treatment, conventional treatment with immunosuppressant medications, and experimental treatment.
Conventional medications include prednisone (an oral corticosteroid medication) and/or cyclophosphamide or azathioprine. These medications are usually given a trial of three to six months and if there is no benefit, then they are discontinued. The benefit of these medications in idiopathic pulmonary fibrosis is fairly minimal, but these drugs can be very effective in some forms of pulmonary fibrosis associated with collagen vascular diseases (such as scleroderma, rheumatoid arthritis, etc.). N-acetylcysteine ("NAC") is an over-the-counter medication taken 3 times a day that may be helpful in some patients with usual interstitial pneumonitis, particularly if coupled with prednisone and azathioprine.
If the pulmonary fibrosis continues to advance despite medical therapy, lung transplantation is often considered. Persons who are candidates for lung transplant from pulmonary fibrosis are generally those who are under the age of 65 and who have developed the need for supplemental oxygen. Patients who are eligible for lung transplant cannot have other serious medical problems (such as cancer or severe heart disease) and cannot be obese (defined as a body mass index of > 30). As the scarring advances, the lung's ability to transport oxygen from the air we breathe into the blood stream becomes diminished and supplemental oxygen is often necessary. Initially, this usually means oxygen is needed during exercise, but it can advance to the point that oxygen is required while at rest as well.
Certain types of pulmonary fibrosis advance more slowly than others. For example, pulmonary fibrosis associated with scleroderma tends to have a more benign course and responds better to therapy; it can often be put into remission permanently. Certain types of idiopathic pulmonary fibrosis have a more favorable prognosis as well. There are several types of idiopathic pulmonary fibrosis, which we define by the microscopic appearance of the lung after biopsy.
Desquamative interstitial pneumonitis has the most favorable prognosis and is almost always caused by tobacco smoke. Smoking cessation and corticosteroids generally result in complete or partial resolution. Respiratory bronchiolitis interstitial lung disease has the next most favorable outcome and is also caused by tobacco smoke. It also is generally treated with smoking cessation with or without corticosteroids.
Non-specific interstitial pneumonitis has a variable response to immune suppressant medications such as steroids and/or cyclophosphamide, azathioprine, or mycophenylate. Usual interstitial pneumonitis occasionally responds to cyclophosphamide (or azathioprine) and corticosteroids; however, it is the least responsive and often progresses despite early drug treatment. A number of new treatments are being investigated for usual interstitial pneumonitis. However, these medications are only available as part of clinical trials.
In patients who develop worsened lung function despite treatment and for those who develop a low blood oxygen level requiring supplemental oxygen, referral for lung transplantation is the best alternative. A number of tests must be done before a patient can be placed on a transplant list so referral is made early if further decline in lung function is anticipated by your doctor.
Patients with pulmonary fibrosis can develop a number of respiratory and nonrespiratory symptoms that can often be annoying.
Supplemental oxygen can greatly improve exercise tolerance and can relieve the sensation of breathlessness. Because of the reduced exercise tolerance, patients often become deconditioned (out of shape), and pulmonary rehabilitation programs can be very useful to help you use your muscles most efficiently.
Often what patients need most is information. This includes satisfactory confirmation of the diagnosis, an honest assessment of the prognosis, and risks and benefits to be reasonably expected from treatment. In this regard, community resources such as the American Lung Association and the Coalition for Pulmonary Fibrosis can supplement some of the information provided by your physician.
This article is a NetWellness exclusive.
Last Reviewed: Aug 11, 2014
James N Allen, Jr, MD
Clinical Professor of Pulmonary, Allergy, Critical Care & Sleep Medicine
College of Medicine
The Ohio State University