INTERSTITIAL LUNG DISEASE: symptoms, digonosis, and treatment
What is Interstitial lung disease?
Interstitial lung disease (ILD) is an umbrella term used for a large group of diseases that cause scarring (fibrosis) of the lungs. ILD damages the tissues between the small air sacs in your lungs (alveoli) and the blood vessels around them. The scarring causes stiffness in the lungs which makes it difficult to breathe and get oxygen to the bloodstream. Lung damage from ILDs is often irreversible and gets worse over time.
Epidemiology
Interstitial lung disease incidence rates in the United States have been difficult to determine. The estimated incidence is 30 per 100000 per year. The overall prevalence is 80.9 per 100000 per year in males and 67.2 per 100000 per year in females. These statistics are derived from one of the most important epidemiologic studies, undertaken in Bernalillo County in New Mexico.
What are the causes of ILD?
- Long-term exposure in your work environment to some toxins and pollutants can damage your lungs. Common agents are mineral dust, organic dust, and toxic gases. Many different types of mineral dust have correlations, but the ones frequently cited with the disease are silica, asbestos, coal mine dust, beryllium, and hard metal. Organic dust includes mold spores and aerosolized bird droppings. Inhaled toxic gases (methane, cyanide) affect the airways either by direct injury or through reactive oxygen molecules. Epidemiologically, the magnitude of exposure-related injuries is hard to measure. It probably occurs even more commonly than estimated. That is why it is invaluable to thoroughly review a patient’s entire employment history and home to look for any evidence of potential agent-disease relationships. (https://www.ncbi.nlm.nih.gov/books/NBK541084/)
- Underlying systemic conditions such as:
- Autoimmune diseases, such as rheumatoid arthritis, scleroderma and mixed connective tissue disease. These diseases result in an immune response that isn't proper and may cause tissue inflammation and scarring in the body, including in the lungs.
- In Sarcoidosis, there is growth of tiny collections of inflammatory cells called granulomas in any part of your body — most commonly the lungs and lymph nodes. Other commonly affected organs include the eyes, skin, heart, spleen, and liver.
- Certain medical interventions can cause interstitial lung disease in some people. This may or may not be reversible based on the type and length of exposure. Medicines more commonly associated with ILD are:
- Chemotherapy drugs: Drugs designed to kill cancer cells, such as bleomycin, gemcitabine, and immune checkpoint inhibitors, can damage lung tissue.
- Heart medicines: Some drugs used to treat irregular heartbeats, such as amiodarone (Nexterone, Pacerone), may harm lung tissue.
- Some antibiotics: Nitrofurantoin (Macrobid, Macrodantin, others) and daptomycin can cause lung damage.
- Anti-inflammatory drugs: Certain anti-inflammatory drugs, such as methotrexate (Trexall, Xatmep, others) or sulfasalazine (Azulfidine), can damage the lungs.
- Idiopathic ILD: The list of substances and conditions that can lead to interstitial lung disease is long. Even so, in some people, the cause is never found. Conditions without a known cause are grouped together under the label of idiopathic interstitial pneumonia. For example:
- Idiopathic pulmonary fibrosis (IPF): is a typically progressive lung disease that occurs when lung tissue becomes damaged and scarred.
- Cryptogenic organizing pneumonia (COP): is a rare lung condition in which the small airways, called bronchioles, and tiny air-exchange sacs, called alveoli, get inflamed. This inflammation makes it hard to breathe. Imaging tests show pneumonia, but COP is not an infection, and the cause is not known.
- Non-specific interstitial pneumonia: This type of interstitial lung disease causes cells to be inflamed or scar tissue to build up in the spaces between the air sacs in the lungs. It's more likely to happen in people with connective tissue diseases, but it also can be linked to other conditions. (https://www.mayoclinic.org/diseases-conditions/interstitial-lung-disease/symptoms-causes/syc-20353108)
Radiation directed at the chest during treatments for certain types of cancers — breast and lung cancers, for example — may lead to injury or long-term scarring in some people. How severe the damage is may depend on the dosage, area, treatment type, and pre-existing lung condition.
What are the risk factors for getting ILD?
The risk of getting ILD is higher for people who:
- Are 70 years or older.
- Assigned male at birth.
- Smoke or used to smoke.
- Have a history of certain illnesses or conditions, like hepatitis C, tuberculosis, pneumonia, COPD, or connective tissue disease.
- Workaround substances that can irritate your lungs, like asbestos, silica, molds, fungi, or bacteria.
- Have had chest radiation.
What are the symptoms of ILD?
Common symptom of interstitial lung disease include:
- Shortness of breath (dyspnea) that gets worse with exercise or exertion.
- Dry cough
- Fatigue
- Chest discomfort
- Air hunger
Symptoms are usually mild at first but get worse over months or years. You may have additional symptoms depending on the underlying cause of ILD. (https://my.clevelandclinic.org/health/diseases/17809-interstitial-lung-disease)
How is ILD diagnosed?
- Pulmonary function tests like spirometry and diffusion capacity help to measure airflow and oxygen diffusion capacity.
- Oximetry helps to measure peripheral oxygenation.
- Imaging tests like X-rays or high-resolution CT can be used to get pictures of your lungs.
- Blood tests can detect proteins, antibodies, and other markers of autoimmune diseases or inflammatory responses to environmental exposures, such as those caused by molds or bird protein.
- Bronchoscopy: Your provider will insert a thin tube (bronchoscope) through your nose or mouth into your lungs to look at your airways.
Biopsy: Your provider will remove a small sample of tissue from your lung and study it under a microscope to help identify the type of ILD. (https://my.clevelandclinic.org/health/diseases/17809-interstitial-lung-disease)
How is ILD treated?
Because there are so many causes, treatment will vary. Some interstitial lung diseases do not have a cure. Treatment is aimed at preventing more lung scarring, managing symptoms, and helping you stay active and healthy. Treatment can’t fix lung scarring that has already occurred.
- Oral medicine, including corticosteroids to reduce inflammation and cyclophosphamide (Cytoxan) to suppress the immune system.
- Oxygen therapy from portable containers
- Lung transplant
- Pulmonary rehabilitation