Asthma is a chronic obstructive airway disease in which the small airways of the lungs constrict, making it difficult to breathe. In recent years, researchers have discovered that much of the process by which asthma leads to difficulty breathing is mediated by the immune system, fostering an understanding of the similarity between asthma and allergy-related lung congestion. Since the immune system is responsible for both disease processes, asthma and allergies often go hand-in-hand, in the form of a combined disease called allergic asthma.
Physiology
Asthma attacks occur when the muscles of the small airways in the lungs contract, causing airways to constrict, explains Dr. Gary Thibodeau in his book, "Anatomy and Physiology." This significantly reduces the ability of the lungs to draw air into the gas exchange sacs deep in the lung tissue, meaning that blood receives less oxygen. The characteristic "wheezing" sound of asthma is the sound of a patient trying to draw air through very narrow passages in an attempt to get more oxygen. Mast cells, notes Thibodeau, are part of the immune system, but are also involved in asthma. When they are activated by an irritant, they release chemicals that lead to small airway constriction.
Significance
With the understanding in recent years that it is immune cells that are largely responsible for constricting airways in asthma, physicians began to make connections between asthma and allergies. Since allergies, too, are the result of mast cell activation by irritant compounds, patients with allergies who also have asthma tend to experience exacerbation of asthma symptoms in response to allergens. MayoClinic.com, for instance, notes that common triggers of allergic asthma include irritants that are also common allergy triggers, including mold, pollen and pet dander.
Considerations
Since allergic asthma is exacerbated by irritant triggers, an important part of controlling symptoms is to reduce exposure to those triggers. The Asthma and Allergy Foundation, for instance, recommends identifying triggers through allergy testing, and then structuring the home environment so as to reduce exposure as much as possible. Carpets and draperies can hold dust and mold, so they recommend window coverings that don't collect dust and tile rather than carpet. Individuals with sensitivities to animal dander should ideally live without pets, but if they choose to have them, they should keep pets out of the bedroom.
Theories/Speculation
With the recognition that some asthmatics are in fact experiencing asthma symptoms in response to allergic triggers, physicians now have new ways to deal with allergic asthma patients. Allergy shots, formally called immunotherapy, have been used for years to reduce symptoms of allergic reactions in allergy sufferers by gradually getting the immune system accustomed to an irritant, so that it no longer reacts to that trigger. MayoClinic.com notes that allergic asthma sufferers may also benefit from immunotherapy; not only will the shots help to reduce allergy symptoms, they'll reduce asthma symptoms as well.
Warning
While asthma can be triggered by allergies, it's important to remember that the two processes don't always go hand in hand. Further, that while allergies are irritating and uncomfortable, they're not life-threatening. Asthma, whether allergic or not, however, can be very serious. As a result, individuals with allergic asthma should rely on their doctor's advice with regard to treatment; over-the-counter allergy medications are generally not sufficient to treat allergic asthma and certainly won't stop an asthma attack, notes MayoClinic.com. Most asthmatics need to carry an emergency inhaler to open airways. These inhalers work much faster than even the most aggressive allergy medications and can save lives.
References
- "Anatomy and Physiology"; Gary Thibodeau, Ph.D.; 2007
- MayoClinic.com: Allergic Asthma
- Asthma and Allergy Foundation: Allergic Asthma
