Related concepts:

Reactive airway disease, wheezy bronchitis, viral-associated wheezing, bronchiolitis

Introduction to asthma:

Asthma is one of the most common disorders affecting children. As many as 10 percent of children have some degree of asthma, and the number has been rising steadily since about 1980. Thankfully, advances in the diagnosis and treatment of asthma have dramatically improved life for these children.

Today most children with properly managed asthma can lead a life unhindered by their disease. It shouldn't hold them back from even the highest levels of athletic competition, as recent Olympic Gold Medals have shown. With proper education and medical management, it is possible to control this disease on a daily basis and prevent asthma attacks.

Having said that, the death rate from asthma increased 46 percent in the last decade in spite of these treatment advances. A major cause of this increase in mortality is improper use of inhalers. Too often, families are handed several inhalers and they never really understand the different functions and uses of each one.

What is asthma?

Asthma is a chronic lung disease characterized by tight airways -- a result of airway hyper-responsiveness. Our airways are designed to be responsive to harmful substances in the air. If we walk through clouds of smoke, our airways will shrink, protecting our delicate lung tissues from the noxious ingredients in the smoke. They should return to normal when we begin to breathe fresh air. People with asthma have an exaggerated tightening response.

Different people with asthma respond to different "triggers.” Viral infections are the most common triggers in young children. Other triggers include smoke, animal dander, pollens, molds, house dust mites, fumes and fragrances, or cold air.

When we exercise, we breathe rapidly and are unable to bring air temperature all the way up to 98.6 degrees -- particularly if we breathe through the mouth. Thus, asthmatics who are sensitive to cold air will often wheeze with exercise. (Wheezing, the classic asthma symptom, is the noise made by air moving through these tight airways.) Because asthmatics respond differently to different triggers, their airways are tighter at some times than at others.

Hyper-responsive airways tighten in three ways in response to triggers. First and most immediately, smooth muscle surrounding the airways constricts, narrowing the caliber of the airways. Second, the airways are narrowed by inflammation and swelling of the airway lining. This leads to the third component of airway narrowing, which is the accumulation of mucus and other fluids, which can plug the airways.

The inflammation is the most important part of the disease. It perpetuates the cycle of airway narrowing.