Special problems of the asthmatic patient.

Environmental factors and physical activity present special problems for the asthmatic patient. Bronchoconstriction due to workplace exposure is one of the most common forms of occupational lung disease and has similar pathogenic mechanisms to nonoccupational asthma. Diagnosing occupational asthma may be difficult because the association between symptoms during or after work and a causative agent may be obscure. Nevertheless, it is important to recognize occupational asthma because even trace amounts of the causative agent may trigger bronchoconstriction, and the affected employee must almost always avoid exposure. Bronchoconstriction induced by exercise has affected the lifestyles of many asthmatic patients and has created special problems for numerous accomplished athletes. Although exercise-induced asthma (EIA) characteristically occurs immediately after cessation of exertion, a recent study suggests that it may sometimes begin during sustained exertion. Asthmatic patients who participate in winter sports are particularly susceptible to EIA. Vocal cord dysfunction in athletes who participate in intense competition can mimic EIA. In addition to beta-agonists used immediately before exercise, newer drugs that show promise in the treatment of EIA include the leukotriene inhibitors and furosemide. Asthmatic patients are susceptible to extremes in atmospheric pressure and have increased risk of barotrauma and arterial gas embolism during scuba diving. During longer stays at high altitude, however, asthmatic patients appear to have attenuated bronchial responsiveness.