Pneumonitis is a general term that refers to inflammation of lung tissue. Pneumonia is one type of pneumonitis caused by an infection. Many other factors can cause pneumonitis, including breathing in animal dander, inhaling small food particles "down the wrong pipe" and receiving radiation therapy to your chest.
A cough and difficulty breathing are the most common signs and symptoms of pneumonitis, but having these problems doesn't necessarily mean that you have pneumonitis. Specialized tests are often necessary to make a diagnosis.
Medications are used to treat some causes of pneumonitis, but other types of pneumonitis can be cured by simply avoiding the substance that triggers inflammation. Identifying and treating pneumonitis promptly is important, because untreated pneumonitis can lead to lung scarring and permanent difficulty breathing.
When you take a breath, air flows down your trachea and enters two airways called bronchi, which direct air to your right and left lungs. From there, air flows into smaller branches of the bronchi called bronchioles and then ends up in clusters of air sacs (alveoli). Oxygen from the air enters tiny blood vessels in the walls of the air sacs. Meanwhile, carbon dioxide, a waste product of metabolism, is released from the blood vessels and makes the reverse journey to exit your
|body when you exhale.
Pneumonitis occurs when some irritating substance — solid particles, liquids, gases, radiation or bacteria — cause the tiny air sacs to become inflamed. This can hamper the exchange of oxygen and carbon dioxide in the air sacs.
There are several types of pneumonitis. They include :
Aspiration pneumonitis. Aspiration pneumonitis occurs when you inhale (aspirate) foreign matter into your lungs. Stomach contents, such as ingested food or liquid, are a frequent cause of aspiration pneumonitis. Accidental inhalation of small food particles, such as tiny pieces of peanuts or vegetables, while swallowing is common in young children.
Chemical pneumonitis is a type of aspiration pneumonitis that develops when you inhale chemicals that are toxic to your lungs. Industrial and household chemicals, such as chlorine gas, ammonia, solvents and pesticides can all cause chemical pneumonitis.
- Hypersensitivity pneumonitis. This type of pneumonitis is nicknamed "farmer's lung," "mushroom picker's disease" and other colorful names with good reason. Dust from animal dander, molds and plants, all potential allergens, can provoke an inflammatory reaction in your lungs. Symptoms usually develop within six hours of exposure to the allergen. Some people are more susceptible to developing hypersensitivity pneumonitis than are others, although it's not certain why.
- Radiation pneumonitis. A few people who undergo radiation therapy for lung cancer, breast cancer, leukemia or lymphoma develop this type of pneumonitis. Taking some types of chemotherapy drugs (doxorubicin, cyclophosphamide, bleomycin) during radiation treatment may increase your risk of developing radiation-induced pneumonitis.
- Drug-induced pneumonitis. A variety of drugs used to treat other conditions can cause pneumonitis. These include certain chemotherapy drugs (bleomycin, methotrexate, carmustine, busulfan, cyclophosphamide), antibiotics (nitrofurantoin, amphotericin B, minocycline), sulfonamides (sulfasalazine, sulfadiazine), nonsteroidal anti-inflammatory drugs (NSAIDs) and the heart medication amiodarone.
Risk factors for developing aspiration pneumonitis include situations that increase your chances of inhaling solids or liquids, especially stomach contents, into your lungs. Seizures, vomiting and undergoing anesthesia are common causes. Others include :
- Medical procedures. A tracheostomy, bronchoscopy or other procedure can interfere with the normal function of the opening at the back of your throat (glottis) leading into the trachea.
- Other disorders. Neurological diseases that can affect your ability to swallow, including multiple sclerosis and Parkinson's disease, or any disorder of the upper gastrointestinal tract, such as gastroesophageal reflux disease (GERD), can lead to aspiration pneumonitis.
The incidence of chemical pneumonitis is usually associated with certain occupational exposures. Cleaning with chlorine bleach in a poorly ventilated area, performing certain types of factory work, such as smelting or welding, and exposure to pesticides or solvents increase the risk of chemical pneumonitis.
In addition, receiving radiation or chemotherapy or taking some types of drugs increases your risk of developing radiation or drug-induced pneumonitis.
When to seek medical advice
Give your doctor a call anytime you have a cough and difficulty breathing, especially if you notice that you develop signs and symptoms that appear after inhaling dust, chemicals or any other substance. Even if your symptoms aren't severe, it's important to get evaluated because chronic pneumonitis can eventually cause lung tissue scarring (fibrosis) and difficulty breathing.
The most common signs and symptoms of pneumonitis are :
- Difficulty breathing
You may also develop :
- A low-grade fever
- A general feeling of being unwell
Other signs and symptoms depend on the type of pneumonitis that you develop. For example, if you breathe in chlorine gas, causing chemical pneumonitis, you may experience a burning feeling in your chest. Chest pain is a feature of radiation-induced pneumonitis. Signs and symptoms of pneumonitis may last anywhere from several hours to days or even longer.
If pneumonitis is left undetected or untreated, you may develop chronic pneumonitis. This is especially common in cases of hypersensitivity pneumonitis, in which you may be continually exposed to an allergen without realizing it. Signs and symptoms of chronic pneumonitis include:
- Shortness of breath while exercising
- Loss of appetite
- Unintentional weight loss
In severe cases, you may begin breathing rapidly (tachypnea) and with difficulty in an effort to meet your body's oxygen demands.
To help determine whether you've been exposed to a substance that may have provoked your signs and symptoms, your doctor will ask you questions about your past and current occupations and your environment, including where you work, if you have pets and whether you've been diagnosed with any allergies. You'll undergo a physical exam, including blood tests, and imaging tests such as a chest X-ray or a computerized tomography (CT) scan of your lungs. To distinguish pneumonitis from other lung disorders, you'll likely have one or more of the following tests :
- Pulmonary function tests. This refers to a series of tests that evaluate how well your lungs are working. A common pulmonary function test, called a spirometry, measures the amount of air that you're able to inhale and exhale in a specific period of time. Your doctor may also measure how efficiently your lungs transfer gases from the air into the bloodstream (diffusion capacity).
Bronchoscopy. A bronchoscopy is a procedure used to view your airways and collect samples from your lungs. In order to make you as comfortable as possible during the procedure, your doctor will spray an anesthetic in the back of your mouth and throat and will give you medication through a vein in your arm to help you relax. A flexible tube called a bronchoscope is passed through your mouth or nose and then down into your lungs.
Once the tube is in place, your doctor may flush a section of your lung with a saltwater solution (saline) to collect lung cells and other materials. This "flushing" procedure is known as a lavage. Your doctor may also insert a tiny needle or brush through the bronchoscope to scrape a sample of cells from the lung tissue (transbronchoscopic lung biopsy).
Pneumonitis that goes unnoticed or untreated can cause irreversible lung damage. Normally, air sacs within your lungs stretch and relax with each breath. Chronic inflammation of the thin tissue lining each air sac can make the air sacs scar and become inflexible. This is called pulmonary fibrosis. In severe cases, pulmonary fibrosis can cause heart failure, respiratory failure and death.
If you have hypersensitivity or chemical pneumonitis, avoiding allergens is a common-sense approach to treatment. By eliminating exposure to the allergen or chemical irritating your lungs, you'll likely notice that your symptoms lessen.
In severe cases of pneumonitis, treatment may include :
- Corticosteroids. Drugs that reduce inflammation, such as prednisone, can help relieve the symptoms of pneumonitis. Corticosteroids are usually taken as a pill. These drugs work by suppressing your immune system, reducing inflammation in your lungs. However, corticosteroid use also increases your risk of developing infections and is associated with the thinning of bones (osteoporosis).
- Antibiotics. Having pneumonitis makes you more susceptible to developing bacterial infections in your lungs. The type of antibiotic you'll receive depends on the bacteria causing the infection. Antibiotic therapy may be given through a vein in your arm or taken as a pill.
- Oxygen therapy. People who have chronic pneumonitis with fibrosis and can't breathe well usually require oxygen therapy. Oxygen therapy involves wearing a mask or a plastic tubing (cannula) with prongs that fit into your nostrils that provides breathing air rich in oxygen. Some people need oxygen therapy constantly, while others might need it only during exercise or sleep.
The outlook following pneumonitis really depends on a variety of factors. Hypersensitivity and aspiration pneumonitis can completely resolve on their own — provided that you've identified the allergen quickly and taken steps to avoid it in the future. If you've developed chronic pneumonitis, irreversible scarring may have already developed.
Even with treatment, radiation and drug-induced pneumonitis are more likely to be associated with long-term lung damage. However, the probability of permanent lung damage varies, depending on radiation and medication dosages, the length of time you're undergoing treatment, and whether you already have lung problems.
Pneumonitis is generally hard to prevent. But one way that you can reduce your risk of developing aspiration pneumonitis is by abstaining from eating or drinking before surgery — if recommended by your doctor. Fasting reduces the risk of inhaling solid particles, liquids or stomach acid during the procedure.
If you've had hypersensitivity or chemical pneumonitis — and have determined what allergen or irritant provoked an inflammatory response in your lungs — you can take steps to prevent it from occurring again.