Asthma is a common disease that affects the lungs. It causes the airways inside the lungs to become…
Interstitial lung disease
- Interstitial lung disease (ILD) is the name for a large group of conditions in which lung scarring leads to breathing problems.
- Risk factors for ILD are increasing age, exposure to lung irritants, and smoking.
- The main symptoms of interstitial lung disease are shortness of breath and a dry cough.
- Once lung tissue is damaged by ILD, the damage cannot be reversed, but treatment can help to manage symptoms and, in some cases, slow the progress of the condition.
What is interstitial lung disease?
Interstitial lung disease (ILD) is a term that covers a large group of medical conditions in which scarring of the lungs leads to long-term breathing problems.
The lungs are sponge-like organs, containing branching airways and millions of tiny air sacs called alveoli. The walls of the alveoli are made up of delicate connective tissue that allows oxygen to travel from air breathed into the lungs into the blood vessels, so it can be transported around the body.
In interstitial lung disease, the tissues of the lungs become scarred and damaged (a state known as fibrosis). It may be due to an abnormal healing response in the lungs.
The scarring reduces the ability of your lungs to expand to take in air and to transport oxygen into the bloodstream. As more of the lung tissue is affected, it becomes more difficult for the body to get the oxygen it needs.
There are also many other causes of ILD. These can include:
- Connective tissue diseases such as rheumatoid arthritis and scleroderma;
- Other diseases such as lymphangioleiomyomatosis and Langerhans cell histiocytosis;
- Exposure to dust and pollutants such as asbestos, silica and animal droppings;
- Exposure to allergens such as pollen and fungal spores;
- Infections such as hepatitis C and Epstein-Barr virus;
- Damage caused to the lungs by gastro-oesophageal reflux disease (heartburn);
- Radiation therapy for lung cancer or breast cancer;
- A wide range of medications, including methotrexate and amiodarone;
- Some recreational drugs, such as heroin, and;
- Inherited conditions, such as tuberous sclerosis and neurofibromatosis.
Factors that can increase the risk of developing interstitial lung disease include:
- Age: although ILD can occur at any age, people are more likely to develop it as they get older;
- Working in occupations in which there is increased exposure to pollutants and dusts, and;
Signs and symptoms
The two main symptoms of interstitial lung disease are:
- Shortness of breath, particularly with physical activity, and;
- A dry cough.
Chest pain or wheezing are uncommon symptoms, but can occur with some types of ILD.
Symptoms of ILD tend to develop gradually, and early on they may be mistaken for just getting older, or being out of shape. If you suspect you have problems with your lungs or breathing, it is important that you have it checked out, since early treatment can help to slow down the damage to the lungs caused by ILD.
Methods for diagnosis
Diagnosing interstitial lung disease is not always straightforward because:
- It has many different types and causes, and;
- Many other medical conditions, such as asthma and chronic obstructive pulmonary disease (COPD), can cause similar symptoms.
It is important for your doctor to identify the condition causing the symptoms because treatments and prognosis can vary. For this reason, your doctor may need to ask you questions about your medical history and your life to help identify what could be causing your symptoms.
Lung function testing
To assess how ILD affects your breathing, your doctor will generally recommend tests to measure lung function, which can include:
- Spirometry, which measures how much air you can breathe in and out, and how fast you can breathe;
- Diffusion capacity, which measures how well gases pass from your breath through your lungs into your bloodstream;
- Oximetry (measurement of arterial blood gases), which can indicate the levels of oxygen in your blood, and;
- An exercise stress test. During this test you perform physical activity, such as riding an exercise bike or walking on a treadmill, while your lung function is monitored.
Other tests that may be used to help diagnose ILD include:
- A chest X-ray or computerised tomography (CT) scans. The pattern of damage to the lung tissue can vary depending on the cause of the condition. These tests may also be used to monitor how your condition progresses;
- Blood tests to check for autoimmune diseases, and;
- Lung tissue samples. Small samples of tissue may be taken via bronchoscopy, in which a thin tube is passed through the mouth or nose and down the windpipe into the lungs. Alternatively, a surgical lung biopsy, in which samples are removed under general anaesthetic, may be recommended.
Types of treatment
Your doctor may recommend:
- Treatment for any underlying medical causes of interstitial lung disease, such as heartburn;
- Stopping any medications that may have caused damage to your lungs, or;
- Stopping or limiting exposure to any pollutants or allergens that may have caused damage to your lungs.
Unfortunately, once lung tissue has been damaged, there is no current treatment that can restore it. Treatments for ILD vary, depending on the cause, and aim to:
- Slow the progression of the condition;
- Improve symptoms, and;
- Help to you to maintain your quality of life as much as possible.
Pulmonary rehabilitation is a type of therapy specifically designed for people with chronic lung conditions who suffer from short breath. A health professional - usually a physiotherapist, exercise physiologist or nurse - will teach you exercises and techniques to help you learn how to maximise your quality of life.
Pulmonary rehabilitation includes:
- Regular, safe physical activity and exercises to promote physical fitness;
- Breathing techniques to help manage breathlessness;
- Information on ways to conserve energy, and;
- Education on healthy eating for people with chronic lung conditions.
Smoking not only increases the risk of developing ILD, but can also make your symptoms worse, and cause the condition to progress more quickly.
If you smoke, your doctor can advise you on treatments and options to help you quit smoking. It is also important to avoid other people's second-hand smoke.
Medications may be recommended to try to help reduce the inflammation and the healing responses that damage the lung.
- Corticosteroids, such as prednisolone, and;
- Immunosuppressant medications, such as azathioprine and colchicine.
These medications have varying rates of success, depending on the type of ILD, but can also have significant side effects. In some cases, particularly if symptoms are mild, your doctor may recommend not using medications and instead simply monitoring your condition.
There is much ongoing research into finding new, more effective medications for ILD. Your doctor may discuss with you whether participating in a clinical trial of one of these medications might be appropriate for you.
If your blood oxygen levels are lower than normal, oxygen therapy can help to reduce breathlessness and the effects on the body.
For cases of ILD that cannot be managed by other methods, a lung transplant may be recommended, particularly for young people.
People with interstitial lung disease can be more vulnerable to respiratory infections and developing pneumonia. Vaccination for pneumonia and flu is an important preventative measure that can help you stay well.
Anxiety and depression
Living with a chronic lung condition can be challenging; people with ILD can be at increased risk of mental health issues such as anxiety and depression. Support groups, counselling or medication may help. If these issues are affecting you, talk to your doctor.
It is a serious condition that can place strain on the right ventricle of the heart and eventually lead to failure of the heart muscle (a type of heart failure). This may require treatment with medication, oxygen therapy or surgery, and can eventually lead to complete respiratory failure and death.
ILD can, in some cases, lead to lung cancer.
Once lung tissue is damaged by interstitial lung disease, the damage cannot be reversed, although treatments can help to manage symptoms and, in some cases, slow the progress of the condition.
Different forms of ILD progress at different rates and some respond to treatment better than others.
Steps that may help to prevent some cases of interstitial lung disease include:
- Not smoking, or giving up smoking if you do, and;
- Following safety precautions with pollutants such as asbestos, silica and bird droppings.