Immunology => Asthma
Asthma, Bronchial (Greek asthma,"panting"), respiratory disease in which spasm and constriction of the bronchial passages and swelling of their mucous lining cause obstruction of breathing, often due to allergy, particularly to dust, animal fur or feathers, moulds, and pollen. Many people with allergic asthma, also called atopic or extrinsic asthma, also suffer from hay fever. Asthma in adults is less likely to be caused by allergy, and more likely to be associated with respiratory infections and emotional upsets. Non-allergic asthma is called intrinsic asthma.
The frequency and severity of asthma symptoms varies markedly from one person to another. A typical attack, which often occurs at night, begins with coughing, wheezing, and shortness of breath, but in some individuals a dry cough may be the only symptom. Even without treatment, attacks usually subside after a few hours, with a change to a moist cough that brings up large amounts of mucus. Attacks may recur in hours or days, or may be absent for months or even years. Status asthmaticus, a prolonged attack that persists despite treatment with drugs, is a particularly severe and sometimes fatal form of the disease, and usually requires hospitalization. Some children with asthma stop having attacks when they reach adulthood.
Asthma attacks can be treated or prevented by a variety of drugs. Inhalation of bronchodilator drugs, such as albuterol or terbutaline, is the usual treatment, and can bring relief within minutes. Severe attacks that do not respond to these drugs may require treatment with corticosteroids. Drugs that can prevent asthma symptoms include theophylline, which is usually taken in tablets, and cromolyn sodium, which is inhaled.
When asthma is associated with allergy to inhaled particles, avoidance of the allergen responsible is generally recommended but often difficult to achieve. Feather pillows and pets can often be avoided, but dust, moulds, and pollens often may not. Skin testing may identify the offending allergens, and periodic desensitizing injections over several years of small amounts of these substances may be helpful.