Bronchial asthma. Asthma is one of the most common respiratory problems in modern industrialized countries, affecting over 5% of the population. It affects all age groups from infants to senior citizens, and mortality rates from asthma appear to be increasing during the past few years in the United States as well as in other industrialized countries. Asthma tends to occur in families, associated with other allergic disease, and may be induced by a wide variety of environmental antigens, most commonly inhaled allergens such as pollen and dust. Bronchial challenge with a specific allergen results in an early bronchospastic response with a relatively brief duration, and in a significant number of patients there is a late response with onset after 3 to 4 hours, lasting hours to days. This late response is associated with a bronchial hypersensitivity reaction, which is demonstrable by nonspecific challenge testing in the laboratory. During the period of bronchial hyperresponsiveness patients are prone to develop attacks following exposure to a wide variety of "triggers," including cold air, fumes, or cigarette smoke. The current approach to management of patients with asthma emphasizes prevention, with avoidance of specific allergens when possible, and chronic use of anti-inflammatory agents including corticosteroids and cromolyn sodium. The goal is to decrease the bronchial hyperresponsiveness. Management of the acute asthma attack consists of bronchodilator therapy, primarily with inhaled beta-adrenergic agonists, and administration of oral or systemic corticosteroids if the attack is not rapidly relieved. Additional therapeutic agents including theophylline and anticholinergics may be useful in some situations. Response to therapy during the first couple of hours in the emergency room is the most important predictor of the course of the acute attack, and patients who have not responded significantly after 2 hours of maximum therapy are candidates for hospital admission or prolonged emergency room observation. The goal of acute therapy is to wean the patient from intravenous drugs and place him or her on rapidly tapering doses of oral prednisone while initiating a vigorous program of preventive therapy. Follow-up observation, both in the office and in the patient's home, is vital and involves extensive patient education and objective testing of peak airflow. In general, the course of asthma is relatively benign compared with other obstructive airway diseases; however, significant mortality exists, especially in older patients and those with late-onset asthma. 