- Asthma can be classified as either allergic (extrinsic) or non-allergic (intrinsic). While both types share many of the same symptoms, what causes the symptoms differentiates them. Allergic asthma symptoms are caused by inhaled allergens that cause an allergic reaction. Allergic asthma, the most common form of asthma, affects more than 10 million people in the U.S. Non-allergic asthma symptoms are triggered by factors unrelated to allergens.
- Asthma triggers are various stimuli that cause asthmatic symptoms. Non-allergic triggers include respiratory infections, physical activity (exercise-induced asthma), cold air, stress and air pollutants (smoke and secondhand smoke). Secondhand smoke may cause asthmatic symptoms in preschool-aged children who have not previously exhibited them. Allergic triggers include animal dander, dust mites, nuts, shellfish, mold spores and pollen.
- Asthma symptoms vary from person to person, with severity ranging from mild episodes of breathlessness to persistent wheezing and coughing. Symptoms may develop over a period of hours, once a person has been exposed to an asthma trigger. Respiratory symptoms include wheezing, shortness of breath and coughing. Wheezing, prevalent during most attacks, is sometimes the initial symptom. In others, a non-productive cough may start an attack. While shortness of breath is a severe symptom, some patients are unaware when they are experiencing it. This lack of awareness puts those patients at risk for more serious attacks. Other symptoms include a rapid heart rate, chest pain and sweating.
- Pulmonary function tests are used to diagnose asthma by measuring the amount of air a person can breathe out of her lungs. Spirometry measures the flow rate and amount of air a person can breathe in and out. Peak airflow measures the rate a person can force air out of their lungs. Patients may inhale a bronchodilator, a medication that opens airways, before and after the pulmonary test. When a person's lung function significantly improves with bronchodilator use, the patient likely has asthma. Doctors may also use known asthma triggers to invoke a reaction. Patients inhale a substance, such as methacholine, that will constrict the airways of an asthma sufferer. The doctor then measures the airway constrictions, using a pulmonary function test.
- Asthma medications may be inhaled, injected or ingested as a pill or liquid. Quick-relief medications relieve the immediate symptoms of an asthma attack. Short acting bronchodilators and beta agonists are inhaled, whereas oral beta agonists and theophylline are taken orally. Long-term control medications reduce the frequency and severity of asthma attacks over a period of time. Anti-inflammatory medications eliminate airway swelling and reduce mucous production. These medications may be non-steroids, such as Cromolyn Sodium (inhaled), or steroids, such as Corticosteroids (inhaled and oral).
