What Is Asthma?
Asthma is a disease that affects the breathing passages, or airways, of the lungs. Asthma is a chronic (ongoing, long-term) inflammatory disease that causes difficulty breathing.
When an exacerbation or "attack" of asthma takes place, the inflammation in the airways causes the lining of the breathing passages to swell. This swelling narrows the diameter of the airway, eventually to a point where it is hard to exchange enough air to breathe comfortably. This is when coughing, wheezing, and the sensation of distress start.
Asthma can have varying intensity of symptoms that are characterized as follows:
- Mild intermittent: Symptoms are less than or equal to two per week and less than or equal to two nighttime awakenings per month. The attacks don't last long, and they are alleviated quickly with medication. There are no symptoms between attacks.
- Mild persistent: Symptoms are greater than two per week but less than one per day and more than two nighttime attacks per month. These worsening symptoms or exacerbations may affect activity.
- Moderate persistent: Daily symptoms include more than one nighttime attack per week. These patients require daily use of short-acting bronchodilators (rescue medication). Exacerbations do affect activity.
- Severe persistent: Continual symptoms result in limited physical activity with frequent nighttime attacks.
There are also several types of asthma.
- Adult-onset asthma develops after age 20. It is less common than asthma in children, and it affects more women than men.
- Exercise-induced asthma involves symptoms that occur about five to 20 minutes after beginning an exercise that involves breathing through the mouth. Sports and games that require continuous activity or that are played in cold weather (for example, long-distance running, hockey, soccer, and cross-country skiing) are the most likely to trigger an asthma attack. Other physical exertions that can trigger an attack include laughing, crying, and hyperventilating. Any activity or environment that dries or cools the airway can result in bronchospasm and symptoms may result (cough, shortness of breath, and chest tightness).
- Occupational asthma occurs in response to a trigger in the workplace. These triggers include contaminants and allergens in the air and extremes of temperature or humidity.
- Nocturnal asthma occurs between midnight and 8 a.m. It is triggered by allergens in the home such as dust and pet dander or is caused by sinus conditions. It is also affected by the natural daily rhythm (circadian clock) of the body's steroid (cortisol) output, which tends to be at the lowest levels in the early morning hours.
Medically Reviewed by a Doctor on 8/6/2014
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