Pulmonary fibrosis (PULL-mun-ary fi-BRO-sis) is a disease in which tissue deep in your lungs becomes thick and stiff, or scarred, over time. The formation of scar tissue is called fibrosis.
As the lung tissue thickens, your lungs can’t properly move oxygen into your bloodstream. As a result, your brain and other organs don’t get the oxygen they need. (For more information, go to the “How the Lungs Work” section of this article.)
Sometimes doctors can find out what’s causing fibrosis. But in most cases, they can’t find a cause. They call these cases idiopathic (id-ee-o-PATH-ick) pulmonary fibrosis (IPF).
IPF is a serious disease that usually affects middle-aged and older adults. IPF varies from person to person. In some people, fibrosis happens quickly. In others, the process is much slower. In some people, the disease stays the same for years.
IPF has no cure yet. Many people live only about 3 to 5 years after diagnosis. The most common cause of death related to IPF is respiratory failure. Other causes of death include pulmonary hypertension (HI-per-TEN-shun), heart failure, pulmonary embolism (EM-bo-lizm), pneumonia (nu-MO-ne-ah), and lung cancer.
Genetics may play a role in causing IPF. If more than one member of your family has IPF, the disease is called familial IPF.
Research has helped doctors learn more about IPF. As a result, they can more quickly diagnose the disease now than in the past. Also, researchers are studying several medicines that may slow the progress of IPF.
These efforts may improve the lifespan and quality of life for people who have the disease.
How the Lungs Work
To understand idiopathic pulmonary fibrosis (IPF), it helps to understand how the lungs work.
The air that you breathe in through your nose or mouth travels down through your trachea (windpipe) into two tubes in your lungs called bronchial (BRONG-ke-al) tubes or airways.
The airways are shaped like an upside-down tree with many branches.
The windpipe is the trunk. It splits into two bronchial tubes, or bronchi. Thinner tubes called bronchioles branch out from the bronchi.
The bronchioles end in tiny air sacs called alveoli (al-VEE-uhl-eye). These air sacs have very thin walls, and small blood vessels called capillaries run through them. There are about 300 million alveoli in a normal lung.
When the air that you’ve just breathed in reaches these air sacs, the oxygen in the air passes through the air sac walls into the blood in the capillaries.
At the same time, carbon dioxide (a waste gas) moves from the capillaries into the air sacs. This process is called gas exchange.
The oxygen-rich blood in the capillaries then flows into larger veins, which carry it to the heart. Your heart pumps the oxygen-rich blood to all your body’s organs. These organs can’t function without an ongoing supply of oxygen.
The animation below shows how the lungs work. Click the “start” button to play the animation. Written and spoken explanations are provided with each frame.
Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames.
The animation shows how the lungs inhale oxygen and transfer it to the blood. It also shows how carbon dioxide (a waste product) is removed from the blood and exhaled.
In IPF, scarring begins in the air sac walls and the spaces around them. The scarring makes the walls of the air sacs thicker. This makes it harder for oxygen to pass through the air sac walls into the bloodstream.
Various things have been suggested as potential causes, or triggers, of the initial damage to the cells lining the alveoli. These include:
- Cigarette smoking. The disease is more common in people who smoke or have been smokers at some time.
- Viral infections. These include viruses such as the Epstein-Barr virus that causes glandular fever, and the hepatitis C virus.
- Certain medicines.
- Pollutants in the environment.
- Gastro-oesophageal reflux disease. This is where there is long-standing reflux of stomach contents into your gullet, which you may then inadvertently inhale into your lungs. See separate leaflet called Acid Reflux and
- Oesophagitis for more detail.
- Idiopathic pulmonary fibrosis also seems to run in some families. However, in about 4 out of 5 cases, there is no family history of the disease.
(A similar fibrotic lung condition sometimes occurs as a result of exposure at work to certain metals, wood dusts and other chemicals, and as a side-effect to certain medicines.
These conditions are not idiopathic, as the cause can be identified. If you have suspected lung fibrosis, your doctor is likely to ask you about your work history to rule out these conditions.)
How common is idiopathic pulmonary fibrosis?
It is rare. Fewer than 3 in 10,000 people develop this disease. However, it seems to be getting more common. It can affect anybody at any age but it most commonly develops between the ages of 50 and 70. It seems to be more common in men than in women.
What are the symptoms of idiopathic pulmonary fibrosis?
Symptoms tend to develop gradually:
- Breathlessness (shortness of breath) that gradually becomes worse is the main symptom. This is due to the reduced amount of oxygen that gets into the bloodstream. Shortness of breath on exertion may be noticed at first. This may be passed off as ‘just getting older’ for a while until the shortness of breath gets worse.
- A dry cough often develops (a cough with little or no sputum).
- Finger or toenail clubbing occurs in about half of cases. Clubbing is a painless swelling at the base of the nails.
- The cause of clubbing is not clear. It occurs in people with various chest and heart diseases.
- An increased risk of developing chest infections.
As the condition progresses, symptoms can sometimes quickly become worse (called an acute exacerbation). Periods of worse symptoms may be followed by periods where there seems to be some improvement.
If the condition becomes severe then heart failure may develop.
This is due to the reduced level of oxygen in the blood and changes in the lung tissue, which can cause an increase in pressure in the blood vessels in the lungs.
This increase in pressure can put a strain on the heart muscle, leading to heart failure. Heart failure can cause various symptoms including worsening breathlessness and fluid retention.
How Is Idiopathic Pulmonary Fibrosis Diagnosed?
Idiopathic pulmonary fibrosis (IPF) causes the same kind of scarring and symptoms as some other lung diseases. This makes it hard to diagnose.
Seeking medical help as soon as you have symptoms is important. If possible, seek care from a pulmonologist. This is a doctor who specializes in diagnosing and treating lung problems.
Your doctor will diagnose IPF based on your medical history, a physical exam, and test results. Tests can help rule out other causes of your symptoms and show how badly your lungs are damaged.
What are the treatment options for idiopathic pulmonary fibrosis?
At present there is no cure for idiopathic pulmonary fibrosis and the optimal treatment has not yet been found. The aim of treatment is to suppress the symptoms as much as possible.
Because idiopathic pulmonary fibrosis was originally thought to be due to inflammation of the alveoli leading to fibrosis and scarring, treatment has been based on medicines to help suppress (reduce) this inflammation.
These included treatments with corticosteroids (steroids) and immunosuppressant medicines such as azathioprine. These medicines are still used to some extent as they can be helpful in some people. Newer medicines are also being studied.
One or more of the following options may be advised to help to improve symptoms, and to slow down the progression of the disease:
Steroid medication may be tried, usually in combination with immunosuppressant medicines. Previous studies showed that steroid medication improved symptoms in about 1 in 4 affected people.
However, some doctors now wonder if these people for whom the steroids worked actually had another type of lung disease. If steroids are prescribed, a high dose is used at first and then reduced to a lower maintenance dose. If there is no improvement after a few months then the steroids are stopped.
Some people who take steroids develop side-effects. See separate leaflet called Oral steroids for more details of possible side-effects.
Immunosuppressant medicines such as azathioprine may also be tried, usually in combination with steroid medication. These also suppress inflammation. Like steroids, they help in just some cases.
No treatment is another option. Medication can cause serious side-effects in some people. The risk of side-effects has to be balanced with the chance of improving symptoms and slowing down the progression of the disease.
No treatment may be advised, particularly for elderly people if their symptoms are mild or are not getting much worse. A chest specialist usually keeps the situation under review.
Oxygen treatment used in the home may be required if symptoms become severe.
Pulmonary rehabilitation courses may help some people. The courses include education about idiopathic pulmonary fibrosis and physical exercise, as well as psychological and social support. Ask the chest clinic that you attend about your nearest course.
Stop smoking if you are a smoker.
Get immunised against influenza and pneumococcus. They protect against infections that can be particularly severe if you have a disease of the lung.
A lung transplant may be an option. This is becoming more common, particularly in younger people who develop severe disease despite medication.
Various newer treatments have been tried. These include interferon, N-acetylcysteine and pirfenidone. These newer medicines are thought to work by having an effect on the fibrosis that develops in the disease.
However, more trials are needed before the benefit of these medicines can be confirmed.
What is the prognosis (outlook)?
The progression of the disease can vary greatly. Some people respond to medication which may slow the progression of the disease but, in others, it makes little difference.
Some people remain stable for many years after being diagnosed, but others deteriorate much more rapidly. It is difficult to predict at the outset how fast the disease will progress for each affected individual.
Lung transplantation has been shown to improve survival in those people for whom it is suitable and so is being increasingly used as a treatment. Newer treatments with medicines may also be shown to be of benefit in the future.