What is airway inflammation?
Airway inflammation is the result of a chronic and persistent irritant or allergen in the airway that results in excess fluid production, excess mucus, increased swelling and redness, and infiltration of immune cells into the lung tissue. Inflammation of this type can be caused by many factors such as cigarette smoking, pollution from traffic fumes, occupational exposures to dust and chemicals, bacterial infections, viruses, fungi, humidity, cold/dry weather, or even strong emotional responses. In many cases, however, the exact cause is never identified.
Small airways become inflamed first and this inflammation often progresses to larger lung regions. As a result, airflow becomes progressively more restricted as inflammation worsens. This progressive narrowing of the airway can lead to respiratory failure over time. In fact, asthma deaths usually result from a lack of sufficient oxygen to maintain life rather than a lack of breath due to respiratory muscle paralysis.
In those with severe asthma, the infiltration of immune cells into lung tissue may be so great that it leads to the destruction of normal lung architecture including destruction or loss of functioning alveoli (microscopic sacs in the lungs where gas exchange occurs) as well as loss of elasticity in associated lung tissues. This process is called acute or chronic bronchiolitis obliterans.
what are the Causes of airway inflammation?
There are many causes of airway inflammation:
- Allergens such as pollen, mold spores, and animal dander.
- Dust and chemicals are seen in those with occupations involving farming or mining.
- Bacterial or viral infections of the lungs (often called pneumonia).
- Air pollution: primarily from car exhaust fumes.
- Trauma to the chest wall may cause lung injury leading to inflammation within the lung over time. This is often called "silicosis" when caused by occupational exposures to silica dust.
What are the symptoms of inflamed airways?
Symptoms of airway inflammation are similar to those who have asthma, COPD, or Cystic Fibrosis. The severity will vary depending on how much the lungs are involved. Symptoms can include cough, chest tightness, wheezing, shortness of breath, excess mucus production, and fatigue. Sometimes there may be no symptoms at all.
What is the proposed pathophysiology behind airway inflammation?
There are two types of cells that make up lung tissue: epithelial cells which line the surface of the airways as well as alveoli (the microscopic sacs in our lungs where gas exchange occurs) and immune cells such as mast cells, eosinophils macrophages, neutrophils, lymphocytes, dendritic cells, T-cells, and basophils.
When immune cells are activated due to an infection or allergen outside of the lung, they release their chemical mediators (called cytokines) which cause inflammation in the lungs. As more and more immune cells infiltrate into lung tissue, obstruction of small airways may occur potentially leading to acute respiratory failure.
If this inflammatory process continues over time it can also begin to destroy normal lung architecture including alveoli, resulting in chronic bronchiolitis obliterans which is often seen with COPD. Some of these chemicals produced by these cells include histamine, bradykinin, leukotrienes, prostaglandins, platelet-activating factor, and tumor necrosis factor.
What are the diagnostic tests used to detect airway inflammation?
There are several diagnostic tools used to help identify if a patient has airway inflammation. These include:
- Spirometry: it measures how much airflow is able to pass through the lungs during exhalation. Increased resistance would suggest that there is a narrowing of small airways within the lung tissue which may be due to inflammation, loss of normal architecture, or obstruction by mucus plugs. Narrowing of these airways can lead to respiratory failure if not adequately treated.
- Blood tests - Testing for eosinophils in the blood often reflects more severe underlying disease activity with asthma or chronic bronchitis. This is because eosinophils are a type of white blood cell type found at the site of inflammation in the lungs.
- Pulmonary function tests - A pulmonary function test that measures obstruction in airflow which is a sign of airway inflammation would include a methacholine challenge. Methacholine contains a chemical that when inhaled leads to the narrowing of small airways within the lung, often called bronchoconstriction. In normal patients, this should not cause any change in forced expiratory volume (FEV) or forced vital capacity (FVC).
- Sputum samples - looking for eosinophils either from direct smear microscopy or performing an ELISA on sputum samples can help identify more severe inflammatory activity inside the lung. However, since the sputum may be difficult or impossible to obtain from some patients with severe underlying respiratory disease, this test is not always helpful in diagnosing acute airway inflammation.
- Blood testing - measurement of the blood tryptase level is often done in cases where aspiration pneumonia is suspected. Tryptase would likely go up if there was an obstruction in the airway preventing normal swallowing of saliva by the patient resulting in bacteria accumulation and subsequent infection of the lung.
- High-resolution computerized tomography (CT) imaging - CT scans are used to detect small changes in lung tissue that can occur even before symptoms become apparent. Some imaging findings seen on CT include loss of normal architecture of small airways making them appear larger than expected, fluid collections in the lung which could be indicative of infection, and reduced lung volume.
- Airway biopsy - A biopsy would need to be performed in order to detect eosinophils that are present within the submucosal layer beneath where cilia are not normally seen. These patients would have inflammation occurring outside the normal location where eosinophils typically accumulate.
- Bronchoscopy with transbronchial BAL (BAL is a type of liquid obtained by performing a bronchoalveolar lavage fluid sample) - This can be done to look further into airway inflammation which may not have been detected during previous diagnostic testing such as direct sputum analysis or high-resolution CT scan imaging. During bronchoscopy, a bronchoscope is inserted into the airway, and saline solution is used to wash out part of the lung. The fluid obtained during this process can be analyzed later on for evidence of inflammation within the lungs.
- Measurement of exhaled nitric oxide (eNO) - High levels of eNO are present in patients with asthma which contributes to oxidative stress within the airways. This increase in oxidative stress can lead to damage to cilia found at the opening of small airways inside the lung. When these cilia are damaged, it will lead to diminished clearance of secretions from the lungs leading to infection or chronic inflammation.
- Atopy patch testing - Diagnosing respiratory allergies using an atopy patch test involves placing a small amount of a substance to which the person is allergic on a patch that's then placed on the skin for 48 hours. If a wheal develops around where the patch was placed, it suggests an allergy to that particular allergen.
- Bronchoalveolar lavage fluid analysis - bronchoalveolar lavage (BAL) involves washing out some of the cells and other material from the lower part of the lung known as alveoli. This can be done using saline solution and what will likely be present within your BAL fluid would involve inflammatory cells such as eosinophils.
- Induced sputum samples - A study involving induced sputum samples would aim at looking at eosinophils within the sputum itself rather than looking at samples on direct smear microscopic examination.
- Airway smooth muscle biopsy - A muscle biopsy would need to be done in order to further assess airway inflammation that could help diagnose asthma or chronic obstructive pulmonary disease (COPD). The test would involve inserting a small needle into the airway while you're under local anesthetic before being able to determine what type of inflammatory cells are being seen on microscopy.
Since it's difficult to make a clinical diagnosis for asthma, other tests needed will depend on your history and physical exam. Keep in mind that lung function testing may not be very helpful in either diagnosing or treating asthma since patients with this condition often have normal or near-normal lung function. When spirometry is done, it may show a low peak flow or FEV1/FEV6 ratio which means that the patient's symptoms are only partly explained by their airflow obstruction.
Treatment for airways inflammation.
The treatment options for airways inflammation are similar to asthma. There are three types of medications that are typically used which include quick-relief, long-term control, and specialty medications. Quick-relief involves the use of bronchodilators while long-term control medications include inhaled steroids.
Specialty medications include leukotriene modifiers (for example, montelukast), inhibitors of cysteinyl leukotrienes (zileuton), and oral mast cell stabilizers (such as cromolyn). For severe cases or in cases where you're experiencing an acute attack that requires immediate attention before your doctor is able to prescribe any medication changes, epinephrine can be given through an inhaler device known as the albuterol rescue inhaler.
How long do Airways stay inflamed?
How long a case of airways inflammation is going to last largely depends on the nature of the specific case. Whether it's due to an acute reaction or whether you have chronic bronchitis, this will likely depend on how often and what kind of pollutants that you're exposed to as well as your genetics. In some cases, it can take weeks before symptoms begin to improve with treatment.
In summary, airway inflammatory disease refers to any condition where there is inflammation in either your upper or lower respiratory tract. The most common causes include allergies and asthma although other causes can include a variety of viral infections such as the flu.
When the cause is unknown, this is known as "idiopathic" meaning that no one really knows exactly what's causing it. Some common signs and symptoms include chest tightness, wheezing, shortness of breath, cough with or without mucous production, fever, muscle aches, or fatigue.
People also read:
How do you treat inflamed airways naturally?
It has been shown that both Vitamin C and E supplementation can help reduce inflammation. Also, many cases show that there is an association with smoking cigarettes which contributes to the inflammatory reaction. As such, quitting smoking should be high on your list of priorities.
Keeping your home clean will also be important since exposure to indoor allergens or air pollutants in urban areas may play a part in provoking symptoms in some individuals (for instance). Lastly, drinking enough water daily can keep airways hydrated while maintaining proper nutrition will make sure you're getting all the essential vitamins and minerals needed for good health.
How do you calm irritated airways?
There are many natural ways in which you can help calm your irritated airways. By staying away from things that cause allergic reactions such as dust, pollen, mold, etc., should help reduce inflammation.
Taking a warm shower or bath can also be soothing for inflamed air passages. Other good remedies include drinking plenty of water to keep inflamed areas well hydrated and applying an earth-based clay mask to the skin (this pulls toxins out of the body while keeping the skin moist).
Also helpful is drinking herbal teas that have calming benefits. For instance, chamomile tea has been shown to be safe and effective in easing coughs while acting as a mild sedative at the same time.
Can ibuprofen help with inflamed airways?
Ibuprofen is a non-steroidal anti-inflammatory drug (NSAIDs) that's available over the counter. It is used for treating fever and mild to moderate pain and can be found in many different colds and flu medications as well as anti-inflammatory formulations such as those containing choline salicylate or diclofenac.