Pulmonary fibrosis

Definition

Pulmonary fibrosis is a serious disease that causes progressive scarring of your lung tissue.

The current thinking is that pulmonary fibrosis begins with repeated injury to the tissue within and between the tiny air sacs (alveoli) in your lungs. The damage eventually leads to scarring (fibrosis), which stiffens your lungs and makes breathing difficult. The most common symptoms are shortness of breath and a dry cough.

Current treatments for pulmonary fibrosis include medications and therapy to improve lung function and quality of life. A number of new therapies for pulmonary fibrosis are in clinical trials. In the meantime, a lung transplant may be an option for some people with pulmonary fibrosis.

Symptoms

Signs and symptoms of pulmonary fibrosis include:

• Shortness of breath (dyspnea)
• A dry cough
• Fatigue
• Unexplained weight loss
• Aching muscles and joints

The most common pulmonary fibrosis symptoms are shortness of breath, especially during or after physical activity, and a dry cough. These often don't appear until the disease is advanced, and irreversible lung damage has already occurred. Even then, you may downplay your symptoms, attributing them to aging, being out of shape or the lingering effects of a cold.

Breathing problems usually become progressively worse, and eventually you're likely to get out of breath during routine activities — getting dressed, talking on the phone, even eating. At this point, symptoms are impossible to ignore.

The course of pulmonary fibrosis — and the severity of symptoms — can vary considerably from person to person. Some people become ill very quickly with severe disease. Others have more-moderate symptoms that grow worse over a period of months or years.

Causes

The process of breathing
Each time you inhale, air travels to your lungs through two major airways called bronchi. Inside your lungs, the bronchi subdivide like the branches of a tree into a million smaller airways (bronchioles) that finally end in clusters of tiny air sacs (alveoli). You have about 300 million alveoli in each lung. Within the walls of the air sacs are small blood vessels (capillaries) where oxygen is added to your blood, and carbon dioxide — a waste product of metabolism — is removed.

What happens in pulmonary fibrosis
In pulmonary fibrosis, microscopic damage to the alveoli causes irreversible scarring of the paper-thin tissue (interstitium) that lines and separates the air sacs. Normally, the air sacs are highly elastic, expanding and contracting like small balloons with each breath. But scarring makes the interstitial tissue stiff and thick and the air sacs less flexible. Instead of being soft and elastic, the air sacs have the texture of a dry, stiff sponge, making breathing much more difficult.

This buildup of scar tissue isn't normal — ordinarily, your body makes just enough tissue to repair damage. But in pulmonary fibrosis, the repair process goes awry.

For people with pulmonary fibrosis, healing may be thwarted in other ways, too. Normally, the body forms new blood vessels to help bring oxygen and nutrients to injured cells. For instance, if you cut your finger, your body sends nutrients to the finger to help promote healing. But in people with pulmonary fibrosis, some of the new blood vessels develop away from or are occluded by the scar tissue.

What damages the lungs?
Hundreds of factors can cause the lung damage that eventually leads to pulmonary fibrosis. Some of the most common include:

• Occupational and environmental factors. Long-term exposure to a number of toxins and pollutants can damage your lungs. Among them are silica dust (silicosis) and asbestos fibers (asbestosis). Chronic exposure to some organic substances, including grain dust, sugar cane, and bird and animal droppings, also can cause fibrosis.
• Radiation. A small percentage of people who receive radiation therapy for lung or breast cancer show signs of lung damage months or sometimes years after the initial treatment. The severity of the damage depends on how much of the lung is exposed to radiation, the total amount of radiation administered, whether chemotherapy also is used and the presence of underlying lung disease.
• Medications. Many drugs can damage your lungs, especially chemotherapy drugs (methotrexate, cyclophosphamide); medications used to treat heart arrhythmias and other cardiovascular problems (amiodarone, propranolol); certain psychiatric medications; and some antibiotics (nitrofurantoin, sulfasalazine).
• Gastroesophageal reflux disease (GERD). Acid reflux, which occurs when stomach acids back up into your food pipe (esophagus), appears to play a significant role in pulmonary fibrosis. Although people with pulmonary fibrosis frequently have GERD, they may not have typical GERD symptoms, such as heartburn and belching.
• Other medical conditions. Serious lung infections such as tuberculosis and pneumonia can cause permanent lung damage. So can disorders that affect tissue throughout your body, not just your lungs, such as systemic lupus erythematosus, rheumatoid arthritis, dermatomyositis, polymyositis, Sjogren's syndrome and sarcoidosis. In rare cases, scleroderma is associated with a particularly severe form of pulmonary fibrosis.

Idiopathic pulmonary fibrosis: When the cause isn't known
The list of substances and conditions that can lead to pulmonary fibrosis is long. Even so, in most cases, the cause is never found. Pulmonary fibrosis with no known cause is called idiopathic pulmonary fibrosis.

Researchers have several theories about what might trigger idiopathic pulmonary fibrosis, including viruses and exposure to tobacco smoke. And because one type of idiopathic pulmonary fibrosis runs in families, heredity also is thought to play a role, even in people who don't directly inherit the disease.

Risk factors

Factors that make you more susceptible to pulmonary fibrosis include:

• Age. Although pulmonary fibrosis has been diagnosed in children and infants, the disorder is much more likely to affect middle-aged and older adults.
• Your sex. In general, men are more likely to have pulmonary fibrosis than women are.
• Occupational and environmental toxins. You have an increased risk of developing pulmonary fibrosis if you work in mining, farming or construction or you're exposed to pollutants known to damage your lungs.
• Radiation and chemotherapy. Having radiation treatments to your chest or using certain chemotherapy drugs makes you more susceptible to pulmonary fibrosis.

Risk factors for idiopathic pulmonary fibrosis
Even though the causes of idiopathic pulmonary fibrosis aren't known, researchers have identified certain factors that seem to increase your risk:

• Smoking. Far more smokers and former smokers develop idiopathic pulmonary fibrosis than do people who have never smoked.
• Genetic factors. A rare type of idiopathic pulmonary fibrosis runs in families. Researchers haven't yet identified the specific genes involved, but they have discovered genetic changes in proteins in the airways and air sacs of people with other types of idiopathic pulmonary fibrosis.
• Viruses. Many people report developing symptoms of pulmonary fibrosis after a viral illness, especially one caused by a herpes virus such as Epstein-Barr, the same virus that causes mononucleosis. As a result, researchers are investigating the role viruses might play in lung disease.

Complications

Complications of pulmonary fibrosis may include:

• Low blood-oxygen levels (hypoxemia). Because pulmonary fibrosis reduces the amount of oxygen you take in and the amount that enters your bloodstream, you're likely to develop lower than normal blood-oxygen levels. Lack of oxygen can disrupt your body's basic functioning, and severely low levels can be life-threatening.
• High blood pressure in your lungs (pulmonary hypertension). Unlike systemic high blood pressure, this condition affects only the arteries in your lungs. It begins when the smallest arteries and capillaries are compressed by scar tissue, causing increased resistance to blood flow in your lungs. This in turn raises pressure within the pulmonary arteries. Pulmonary hypertension is a serious illness that becomes progressively worse and may eventually prove fatal.
• Right-sided heart failure (cor pulmonale). This serious condition occurs when your heart's lower right chamber (ventricle) has to pump harder than usual to move blood through blocked pulmonary arteries.
• Respiratory failure. This is often the last stage of chronic lung disease. It occurs when blood-oxygen levels fall dangerously low. Low blood-oxygen levels can lead to heart arrhythmias and unconsciousness.

Preparing for your appointment

If your primary care doctor suspects a serious lung problem, you're likely to be referred to a pulmonologist, a doctor who specializes in lung disorders. To help you get the most from your appointment:

• Be aware of any pre-appointment restrictions. At the time you make your appointment, be sure to ask if there's anything you need to do in advance to prepare for diagnostic tests you might have.
• Write down all symptoms and changes you're experiencing, even if they seem unrelated to your lungs or breathing.
• Write down key personal information, including any recent life changes or other stressors.
• Make a list of important medical information, including recent surgical procedures, the names of medications you're taking and any other conditions for which you've been treated.
• Write down questions to ask your doctor. For instance, you'll want to learn more about treatment options for pulmonary fibrosis and the long-term outlook for people who have the disease.
• Have a friend or family member accompany you. Pulmonary fibrosis is a serious and complex disease. A friend or family member can provide emotional support and help remember information that you may have forgotten or missed.

Tests and diagnosis

Diagnosing pulmonary fibrosis can be extremely challenging. The difference between idiopathic and nonidiopathic forms of the disease isn't always clear, and the naming and classification systems for both have historically been confusing and controversial. In addition, many medical conditions, including chronic obstructive pulmonary disease (COPD), asthma and even heart failure, can mimic pulmonary fibrosis, so doctors must rule these out before making a definitive diagnosis.

A complete medical history, physical exam and even a chest X-ray aren't enough to diagnose pulmonary fibrosis, but they can help exclude other conditions. For that reason, you may have tests such as:

• Chest X-ray. This will usually show the scar tissue typical of pulmonary fibrosis and is useful for following the course of the illness and treatment. Occasionally, the chest X-ray is normal and further tests are required to explain the unexplained shortness of breath (dyspnea).
• High-resolution computerized tomography (HRCT) scan. This provides sharper and more-detailed images of your lungs than do conventional CT scans or regular chest X-rays.
• Pulmonary function tests. These tests determine how well your lungs work overall. They measure how much air your lungs can hold, and how quickly you can move air in and out of your lungs.
• Oximetry. This simple test uses a small device placed on one of your fingers to measure the oxygen saturation in your blood. Oximetry can serve as an easy way to monitor the course of the disease, sometimes more accurately than a chest X-ray can.
• Exercise stress test. An exercise test on a treadmill or stationary bike may be used to monitor your lung function when you're active.

Often, though, pulmonary fibrosis can be definitively diagnosed only by examining a small amount of lung tissue (biopsy) in a laboratory. The tissue sample may be obtained in one of these ways:

• Bronchoscopy (transbronchial biopsy). In this procedure, your doctor removes very small tissue samples — generally no larger than the head of a pin — using a small, flexible tube (bronchoscope) that's passed through your mouth or nose into your lungs. The risks of bronchoscopy are generally minor — most often a sore throat and temporary hoarseness from swallowing the bronchoscope — but the tissue samples are sometimes too small for an accurate diagnosis.
• Bronchoalveolar lavage. In this procedure, your doctor injects salt water (saline) through a bronchoscope into a section of your lung, and then immediately suctions it out. The solution that's withdrawn contains cells from your air sacs. Although bronchoalveolar lavage samples a larger area of the lung than other procedures do, it may not provide enough information to diagnose pulmonary fibrosis.
• Surgical biopsy (video-assisted thoracoscopic surgery). In some cases, your doctor may recommend a surgical biopsy. Although this is a more invasive procedure with potential complications, it's often the only way to obtain a large enough tissue sample to make an accurate diagnosis. During the procedure, surgical instruments and a small camera are inserted through two or three small incisions between your ribs. The camera allows your surgeon to view your lungs on a video monitor while removing tissue samples from your lungs. Because video-assisted thoracoscopic surgery doesn't require cutting through a rib, you're likely to have less pain and to heal more quickly than you are with traditional open-lung surgery.

Treatments and drugs

The lung scarring that occurs in pulmonary fibrosis can't be reversed, and no current treatment has proved effective in stopping the ultimate progression of the disease. Some treatments, though, may improve symptoms temporarily or slow the disease's progress. Others help improve quality of life.

Medications
Many people diagnosed with pulmonary fibrosis are initially treated with a corticosteroid (prednisone), sometimes in combination with other drugs that suppress the immune system, such as methotrexate or cyclosporine. None of these combinations has proved very effective. Adding N-acetylcysteine, a derivative of a natural amino acid, to prednisone may slow the disease in some people. And in clinical trials, the drug pirfenidone has been shown to improve lung function and prevent destruction of lung tissue.

Prednisone and other immunosuppressant medications can also cause serious side effects, including diabetes, glaucoma, reduced production of red blood cells, skin cancer and lymphoma. For that reason, treatment is usually discontinued if there's no improvement after six months. Although some people improve temporarily on immunosuppressant drugs, it's not clear why some people respond and others don't.

Lung transplantation
Lung transplantation may be an option of last resort for younger people with severe pulmonary fibrosis who haven't benefited from other treatment options. In order to be considered for a transplant, you must agree to quit smoking if you smoke, be healthy enough to undergo surgery and post-transplant treatments, be willing and able to follow the medical program outlined by the rehabilitation and transplant team, and have the patience and emotional strength and support to undergo the wait for a donor organ. The last requirement is particularly important because donor organs are in short supply.

Other treatment approaches
Other pulmonary fibrosis treatments focus on improving quality of life. They include:

• Oxygen therapy. Using oxygen can't stop lung damage, but it can make breathing and exercise easier, prevent or lessen complications from low blood-oxygen levels, and improve your sleep and sense of well-being. It can also reduce blood pressure in the right side of your heart. You're most likely to receive oxygen when you sleep or exercise, although some people may use it round-the-clock.

• Pulmonary rehabilitation. This is a formal program for people with chronic lung disease that includes, but goes far beyond, medical management. The aim of pulmonary rehabilitation is not only to treat a disease or even improve daily functioning, but also to help people with pulmonary fibrosis live full, satisfying lives. To that end, pulmonary rehabilitation programs focus on exercise, on teaching you how to breathe more efficiently, on education, and on emotional support and nutritional counseling.

  Most often, this multifaceted approach requires a team of health care professionals that may include a doctor, nurse, rehabilitation specialist, dietitian and social worker. Programs can vary widely, however. Your doctor can usually tell you about pulmonary rehabilitation programs in your area. Or contact the American Lung Association for more information.

Treatments under investigation
A number of treatments for pulmonary fibrosis are being developed or are in clinical trials. You can find an extensive listing of clinical trials in the National Institutes of Health clinical trial database on the Web. You can also contact the National Heart, Lung, and Blood Institute for more information. If you think you might be interested in participating in a clinical trial, your doctor can help you find an appropriate program.

Lifestyle and home remedies

Being actively involved in your own treatment and staying as healthy as possible are essential to living with pulmonary fibrosis. For that reason, it's important to:

• Stop smoking. If you have lung disease, the best thing you can do for yourself is to stop smoking. Talk to your doctor about options for quitting, including smoking-cessation programs, which use a variety of proven techniques to help people quit. And because secondhand smoke can be just as harmful to your lungs, don't allow other people to smoke around you.
• Exercise regularly. Exercise is a double-edged sword for people with lung disease. It can make you more short of breath temporarily, yet it helps maintain lung function, reduces stress and improves overall health and well-being. If you're already exercising, don't stop. And if you're not currently physically active, talk to your doctor about an exercise program that might be best for you.
• Eat well. People with lung disease may lose weight both because it's uncomfortable to eat and because of the extra energy it takes to breathe. Yet a nutritionally rich diet that contains adequate calories is essential. A dietitian can give you further guidelines for healthy eating.
• Get plenty of rest. Getting at least eight hours of good-quality rest every night can boost your immune system and sense of well-being.
• Control GERD. If you've been diagnosed with GERD, it's essential to keep it under control. You can help reduce acid reflux by waiting at least three to four hours after eating before lying down, eating smaller meals, avoiding any foods that trigger your symptoms and maintaining a healthy weight.