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Interstitial Lung Diseases
What is Interstitial Lung Disease?
The interstitial lung diseases (ILDs) are a group of diseases that lead to lung damage and ultimately fibrosis with loss of the elasticity of the lungs. They are chronic conditions characterised by shortness of breath. There are more than 200 related diseases of the lung known as interstitial lung diseases (ILD). Another term often used for ILDs is “pulmonary fibrosis.” Idiopathic pulmonary fibrosis (IPF) is the most common cause of pulmonary fibrosis. In the ILDs, the lung tissue becomes thickened, stiff and scarred over a period of time. The development of the scar tissue is called fibrosis. As the lung tissue becomes scarred and thicker, the lungs lose their ability to transfer oxygen into the bloodstream. As a result, the brain and other organs don’t get the oxygen they need. The scarring typically progresses making it more difficult to breathe.
What Causes Interstitial Lung Disease?
The cause of the interstitial lung disease may not always be apparent, but may be due to:
- Environmental factors (particularly exposure to certain types of dusts or other allergens) such as in:
– Asbestosis (caused by asbestos exposure, often many years before).
– Hypersensitivity Pneumonitis (HP; also called Extrinsic Allergic Alveolitis, EAA) that may be seen with bird keepers and farmers. In some cases, a patient may be found to have HP/ EAA, but the allergen is not known.
- Autoimmune (or rheumatological) diseases in which the patient’s own immune system attacks their body, such as:
– Rheumatoid Arthritis,
– Systemic Sclerosis (also called Scleroderma), and
– Systemic Lupus Erythematosis (SLE),
– Wegeners Granulomatosis, Churg Strauss Syndrome and other vasculitides .
- Drug reactions, in particular amiodarone, nitrofurantoin and other drugs, have been reported to cause ILD in a small percentage of people that take them over a long time.
- Sarcoidosis is another cause of ILD that is discussed in a separate leaflet.
- There are many other rarer ILDs, but we have dealt with the most common ones here. If you need information about the others, please ask your doctor in clinic.
In all these cases, the interstitial inflammation changes the lung’s ability to function normally. Typically, mild scarring of the lung tissue occurs first, but over months and years, the normal lung tissue is replaced by more heavily scarred lung tissue, which makes it difficult to breathe and deliver needed oxygen to the body.
ILD affects each person differently and the diseases progress at varying rates. For some, the scarring occurs quickly, while in others, it happens over a longer period of time. Symptoms also vary from moderate to severe and may stay the same for a while.
What Are The Symptoms Of ILD?
Symptoms of ILD usually develop gradually and may not be noticed until the disease is well established. Because the disease may develop later in life, a common assumption is that the breathlessness is just part of middle age. If you feel breathless, you should see your doctor. Symptoms may include:
- Dry cough (can be chronic dry, hacking coughing).
- Shortness of breath, especially during or after physical activity.
- Lasting tiredness.
- Weight loss.
- Bulb-like changes of the fingertips and nails (a condition called clubbing).
Often, we do special tests to look for ILD in patients who attend the hospital for other reasons. For example, we routinely do lung function tests on our patients with underlying rheumatological diseases so that we can pick up lung disease early and treat it.
Sometimes, lung disease is the first indication of an underlying rheumatological disease and may occur many years before the patient develops joint pains or other features of these diseases. This is why, when anyone first comes to the clinic with pulmonary fibrosis, we always ask them about their joints, dry eyes, dry mouth and cold fingers as these are clues that there is more going on than just lung disease. We also do blood tests to look for evidence of rheumatological diseases. We also ask about hobbies, jobs, pets and exposure to certain drugs or toxins (such as asbestos).
Diagnosis of ILD can be difficult. The symptoms are similar to those of other diseases such as asthma, chronic obstructive pulmonary disease (COPD) and congestive heart failure. Additionally, ILD can co-exist with these diseases.
In order to confirm the diagnosis of ILD and establish the cause, doctors must take some time to explore and eliminate other possible diagnoses.
Confirming diagnosis may involve one or more of the following tests:
- Blood tests including tests of auto-antibodies, and antibodies against common allergens.
- Pulmonary function test to measure breathing capacity.
- X-ray and CT (“CAT”) scan of your chest to identify the pattern of scarring in your lungs.
- Lung cell sample by passing a small flexible telescope (a bronchoscope) down the breathing tubes in order to examine cells and look for signs of inflammation.
- Lung biopsy.
Sometimes, during examination of the lungs with a stethoscope, a doctor may hear crackling sounds in the chest. These crackles have a very characteristic sound.
The lung function test may show a reduction in the volume of the lungs and the transfer factor (or diffusing capacity) is a measure of the ability of the lungs to exchange gases (oxygen and carbon dioxide) into and out of the blood stream.
The chest X-ray may or may not be abnormal, but a high resolution CT scan will often show abnormalities. The CT may show non specific interstitial pneumonitis (NSIP) or the more classic usual interstitial pneumonitis (UIP). UIP on the CT scan of lung shows up as a scarring of the lungs with small bubbles, that have a characteristic appearance called “honeycomb”.
If your scan shows UIP, all the blood tests are normal and there is no reason found for the honeycomb (UIP) pattern on the CT scan, then the doctor will make a diagnosis of IPF (see IPF section).
If your scan shows NSIP, this makes IPF less likely and your doctor will look even harder for an underlying cause for your lung fibrosis and may suggest a lung biopsy. The biopsy specimen is examined microscopically by a pathologist to confirm the presence of fibrosis. This may show either that the patient has IPF even though the CT scan was not classic, or that this is not a case of IPF and there must be another cause for the fibrosis.
At UCLH, we only carry out a small number of lung biopsies and only in cases in which being more confident about the diagnosis will really make a difference to a patient’s treatment.
Can ILDs Be Treated Or Prevented?
If the lung fibrosis/ ILD is due to exposure to a drug or an allergen (eg bird feathers), then the doctors will suggest that you stop the drug or avoid the allergen, if possible. Sometimes, we will use a trial period of stopping a drug if we are not 100% confident that that drug or allergen is responsible.
Some types of lung fibrosis/ILDs may respond to corticosteroids and other medications that suppress the body’s immune system by decreasing the processes that lead to fibrosis. The goal is to decrease lung inflammation and subsequent scarring.
The side effects of treatments can be serious and a lung specialist is required to determine what treatment is appropriate.
Pulmonary fibrosis causes decreased oxygen levels in the blood which can lead to a condition known as pulmonary hypertension, and patients with pulmonary fibrosis are frequently treated with supplemental oxygen to prevent heart failure. Patients with lung fibrosis will have annual echocardiograms to make sure that they are not developing pulmonary hypertension
In addition to the medicines, there are also non-drug approaches available that can help manage ILDs symptoms. Pulmonary rehabilitation, often combined with oxygen therapy, may help improve the ability to function without severe breathlessness.
Pulmonary rehabilitation involves nutritional advice, exercise and breathing techniques whilst oxygen therapy allows you to continue being as active as possible.
Living With ILD
Please consult your doctor before making changes to your lifestyle.
- Quit smoking to help increase oxygen levels in your blood and lower blood pressure and heart rate.
- Eat less saturated fat and more fruits and vegetables.
- Exercise to help keep your body working as efficiently as possible.
- Lose excess weight to help improve your breathing capacity.
- Avoid situations in which you might catch infections from others.
- Avoid excessive pollutants and dust.
- Try to stay mentally active.
- Seek emotional support through family, friends, healthcare providers and support groups.
- Don’t over exert yourself and ensure you get enough rest.
- Make sure your immunisations are up to date.
- You may be asked to take calcium and vitamin D to protect your bones if you are on long term steroids.
Ongoing Research at UCL Respiratory
Our fantastic research team at the Centre for Inflammation and Tissue Repair (CITR) at UCL, aims to find better ways to diagnose, treat, and ultimately find a cure for pulmonary fibrosis. The research is both clinical, involving patients, and laboratory based.
Click here for more information on Breathing Matters Clinical Trials in ILD