Diagnosing Asthma.

Asthma diagnosis is based on repeated, careful measurements of how efficiently the patient can force air out of the lungs and on a thorough medical history and laboratory tests to find out what triggers the patient's acute attacks. People with asthma react to external irritants in a way that non-asthmatics don't. Many, but not all, sufferers have allergies that cause their bodies to produce an abnormal array of chemicals in response to environmental allergens. In that sense, asthma is like pollen allergies, hives, and eczema. But in asthma, the allergic reaction contributes to inflammation of the airways rather than of skin, eyes, or nose and throat. An acute asthma attack may come on rapidly after exposure to an irritant or develop slowly over several days or weeks, which can complicate the job of identifying a patient's asthma triggers. Which drugs asthma patients need, when to use them, and how much to use depend largely on the character of their illness, as shown by the degree of breathing impairment and the frequency and severity of acute attacks. Many docotors and researchers agree that the first line of defense is avoidance of whatever brings on an acute asthma episode. In some asthmatics, attacks can be brought on by strenuous exercise, exposure to cold outdoor air, industrial or household chemicals and food additives such as sulfites. Influenza or even cold viruses can also trigger asthma episodes. There are many cases where triggers cannot be identified, even after a thorough investigation.