Definition
Asthma is an inflammatory disorder of the airways, which causes attacks of wheezing, shortness of breath, chest tightness, and coughing.
See also: Pediatric asthma
Alternative Names
Bronchial asthma; Exercise-induced asthma
Causes, incidence, and risk factors
Asthma is caused by inflammation in the airways. When an asthma attack occurs, the muscles surrounding the airways become tight and the lining of the air passages swell. This reduces the amount of air that can pass by, and can lead to wheezing sounds.
Most people with asthma have wheezing attacks separated by symptom-free periods. Some patients have long-term shortness of breath with episodes of increased shortness of breath. In others, a cough may be the main symptom. Asthma attacks can last minutes to days and can become dangerous if the airflow becomes severely restricted.
In sensitive individuals, asthma symptoms can be triggered by breathing in allergy-causing substances (called allergens or triggers).
Common asthma triggers include:
- Animals (pet hair or dander)
- Dust
- Changes in weather (most often cold weather)
- Chemicals in the air or in food
- Exercise
- Mold
- Pollen
- Respiratory infections, such as the common cold
- Strong emotions (stress)
- Tobacco smoke
Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) provoke asthma in some patients.
Many people with asthma have an individual or family history of allergies, such as hay fever (allergic rhinitis) or eczema. Others have no history of allergies.
Signs and tests
Allergy testing may be helpful in identifying allergens in patients with persistent asthma. Common allergens include pet dander, dust mites, cockroach allergens, molds, and pollens. Common respiratory irritants include tobacco smoke, pollution, and fumes from burning wood or gas.
The doctor will use a stethoscope to listen to the lungs. Asthma-related sounds may be heard. However, lung sounds are usually normal between asthma episodes.
Tests may include:
- Arterial blood gas
- Blood tests to measure eosinophil count (a type of white blood cell) and IgE (a type of immune system protein called an immunoglobulin)
- Chest x-ray
- Lung function tests
- Peak flow measurements
