A chronic condition of the lungs, asthma occurs when inflammation causes airways to narrow, resulting in wheezing, coughing, difficulty breathing and chest tightness. It affects the primary airways, called bronchi, and their branches, called bronchioles.
Between 12 and 15 million Americans have asthma. It is the nation's single leading cause of chronic illness in children, affecting about five million of children under age 16. The most common cause of hospitalization in children, asthma is responsible for one-third of pediatric emergency room visits.
For reasons not fully understood, the bronchi of some people are hypersensitive to certain environmental triggers. Exposure to these triggers can cause airways to contract and become inflamed, narrowed, and clogged with mucus. Less room is available for air to flow in and out of the lungs.
Asthma attacks range from mild to severe, and last anywhere from a few minutes to several days. During attacks, bronchial muscles go into spasm, causing air to be trapped in tiny air breathing sacs called alveoli. To understand what a severe asthma attack feels like, take a deep breath, hold it in and attempt to take another breath.
Asthma attacks may be fatal if not identified and managed. Asthma is currently blamed for 5,000 American deaths a year.
Asthma treatment generally includes a combination of avoidance of known triggers, education in self-management and asthma medications. Two types of medications exist: Anti-inflammation medicines reduce the underlying inflammation that makes airways more vulnerable to an attack. Bronchodilators relieve acute attack symptoms.
Chronic asthma sufferers also must carefully monitor their breathing capacity with a home peak flow meter, a device that measures how quickly you can expel air from your lungs. With proper medical care, most people with asthma can live fulfilling and productive lives with a normal life expectancy.
Even with advances in diagnosis and treatment of asthma, in the past few decades the prevalence of asthma has been rising steadily throughout the world. In the United States, asthma rates increased 75 percent between 1980 and 1994, and cases in children rose 160 percent. Epidemiologists, the scientists who track the spread of disease, speak of a worldwide asthma epidemic but the reasons for it remain elusive. A number of causes are cited — for example, "tighter" houses with less air circulation, increased exposure to toxins and allergens, and increase of industrial pollutants. Most likely, the asthma epidemic results from a combination of an increase in known triggers and from other factors that are not yet understood.