What is asthma?
Asthma is a common disease of the lungs characterized by intermittent episodes of shortness of breath, wheezing, cough, and chest tightness. The prevalence of asthma is increasing, and asthma now affects approximately 8% of the population. The prevalence of asthma varies around the world but is highest in Western countries.
What causes asthma?
Asthma occurs in genetically susceptible people with environmental stimuli (especially in young childhood) that promote asthma. Environmental stimuli associated with the development of asthma include allergens, viruses, bacteria, airborne irritants, obesity, and occupational exposures. More research is needed to understand the relative importance of these different stimuli and the time windows that are important for specific environmental exposures.
As an example, although asthma is more common in people who also have allergies, it is not known why only ~25% of people with nasal allergies develop asthma. It is also not known why asthma is severe in some patients but relatively mild in most.
Why do the airways (“bronchial tubes”) narrow in asthma?
There are three main reasons for narrowing of the airways in asthma:
- Inflammation, or swelling, of the lining of the airway
- Bronchoconstriction, which happens when the muscles that wrap around the airway tighten and squeeze the airway
- Mucus overproduction, which happens when the airway makes too much mucus and blocks part or all of the airway
Narrow airways cause the symptoms of asthma, which are shortness of breath, wheezing, coughing, and chest tightness.
How is asthma diagnosed?
Asthma is diagnosed based on a person’s history of symptoms often with tests done in the clinic. These tests include:
- Lung function tests: Common lung function tests in asthma are spirometry and peak flow measurement (often done with a handheld device). These tests show if your airways are narrow and if that narrowing is reversible with inhaled medication
- Measures of allergy: Allergy tests include skin prick tests or blood tests (for allergy antibody or for specific kinds of white blood cells, especially eosinophils). Asthma is common in people with environmental allergies and allergen avoidance may help control asthma.
How is asthma treated?
Treatment is important to provide symptom relief and reduce the risk of attacks. Treatment includes asthma medications, trigger avoidance, and disease education. People with asthma usually work with a health care provider to make an asthma treatment plan. This can include:
- Trigger avoidance
- Peak flow monitoring
- An asthma action plan - what to do when symptoms or peak flow get worse
Asthma attacks are periods of uncontrolled asthma with increased symptoms of shortness of breath, wheezing, coughing, and chest tightness. Asthma attacks can come on quickly following a specific exposure (e.g. cat dander exposure) or during exercise. Attacks can also come on more slowly (e.g., asthmatics who get a cold often notice that their asthma gets worse over a day or two).
Mild asthma attacks may be controlled with inhalations of rescue medication. More severe attacks, however, require a visit to an urgent care clinic or to the emergency room. Asthma attacks need to be taken seriously because they can sometimes be severe and even life threatening. Clues to a more serious attack include severe symptoms that are not relieved by rescue medication. In addition, a history of prior attacks requiring treatment in an emergency room or in an intensive care unit should alert a patient that their asthma might be more severe. Although death from acute asthma attacks is relatively uncommon, it does occur, and an important warning sign is a previous severe attack of asthma.
What can someone who was recently diagnosed with asthma expect for their future health?
There is currently no cure for asthma. Medications and treatment plans can help reduce symptoms. While asthma can be very severe for some people, most people can lead normal lives with proper treatment.