Asthma

  

 

Definition of Asthma

Asthma is a disease of the airways that results in narrowing of the airways (bronchospasm) and INFLAMMATION in response to a wide range of inhaled irritants such as pollen,

mold, smoke, chemicals, and the airborne debris of pests ranging from cockroaches to microscopic dust mites. This narrowing, or airflow obstruction, is usually reversible when the person can eliminate the exposure or through treatment with medications called bronchodilators. Repeated exposure to irritants in susceptible people can result in repeated episodes of inflammation. This pattern can ultimately cause scarring of the airways that is not reversible.

Nearly 18 million Americans have asthma, a third of whom are under age 18. For many of them asthma attacks are mild and infrequent, giving the perception that asthma is a common and, though annoying, harmless condition. However, lifethreatening consequences can occur during a severe asthma attack. If the person does not receive rapid and effective treatment, the airway narrowing and inflammation can completely block the flow of air. The person cannot exhale (breathe out) fully, lowering oxygen levels and potentially causing death. Nearly 5,000 Americans die each year as a consequence of asthma or its complications.

 

Signs and Symptoms of Asthma and Diagnostic Path

An asthma attack generally follows a pattern of symptoms that, though it varies among people who have asthma, tends to be consistent for each individual. Some people first experience DYSPNEA (shortness of breath) or wheezing (a high-pitched whistling sound with exhalation), for example, while other people find a restless night with frequent waking foreshadows an asthma attack that manifests the following day. Common symptoms of asthma attacks include

• dry, nonproductive COUGH


• sense of tightness in the chest


• dyspnea, especially during physical activity


• wheezing


• gasping for air

There are no definitive tests for asthma. The diagnostic path may include tests and procedures, such as chest X-RAY and complete BLOOD count (CBC), to rule out other causes of symptoms. The pulmonologist will conduct pulmonary function tests to measure the flow and volume of air, typically before and after administration of a bronchodilator medication that relaxes and opens the airways. People who have asthma generally have much improved pulmonary function test results after the bronchodilator, even when they are having no symptoms of asthma at the time of testing. However, the reverse can also be true and the person has normal breathing tests during a time of no symptoms. In such cases, the pulmonologist may conduct a test called a methacholine challenge, administering the DRUG methacholine to see whether it initiates a mild hypersensitivity reaction. A positive response (symptoms appear) is fairly conclusive of an asthma diagnosis.