Overview of Asthma
Asthma is a chronic disease that affects the airways and lungs. According to the World Health Organization (WHO), approximately 235 million people worldwide are affected by asthma. Asthma is the most common chronic disease in children.
The Centers for Disease Control and Prevention (CDC) reports that the number of people with asthma increased by 4.3 million from 2001 to 2009 and that during this time period, asthma rates rose the most (almost 50 percent) in black children. In 2007, asthma was linked to 3,447 deaths in the United States.
Severe asthma is a serious health concern that can lead to respiratory failure. Each year in the United States, as many as 470,000 people seek hospital treatment for asthma-related symptoms and the disease causes about 5000 deaths.
Despite its prevalence, experts differ in the definition of the disease. Clinical authorities typically favor a broad, comprehensive definition. The National Heart, Lung and Blood Institute, for example, defines asthma as:
- "a chronic inflammatory disorder of the airways (which causes recurrent episodes of wheezing, breathlessness, chest tightness and coughing, particularly at night or in the early morning) usually associated with widespread but variable airflow obstruction that is often reversible, either spontaneously or with treatment."
Organizations geared primarily toward the informational needs of patients usually promote, simpler, more "user-friendly" definitions. The American Lung Association, for example, defines asthma as:
- "a chronic disease of the lungs in which the airways overreact to certain factors by becoming inflamed or obstructed, making it difficult to breathe comfortably."
Other authorities maintain that asthma is not a single disease, but a group of closely related diseases with common clinical symptoms.
Asthma is a condition in which the bronchial tubes in the lungs react to different stimuli by becoming inflamed. These asthma triggers vary and may include exercise, cold air, allergens (such as dust, ragweed, mold, or cat dander), infections, and emotional reactions. Inflammation of the bronchial airways causes them to become constricted and narrowed. This narrowing of the airways, called bronchoconstriction, produces the symptoms: shortness of breath, tightness in the chest, coughing, and wheezing.
Some people suffer asthma symptoms continuously; others experience them only if exposed to triggers. Regardless of the cause, severe asthma is a serious health concern that can lead to respiratory failure and death.