Asthma is a respiratory disorder marked by breathing difficulty caused by temporary narrowing of the bronchi, the airways branching from the trachea to the lungs. Attacks usually are brought on by allergic reaction to ANTIGENS such as grass and tree pollens, mold spores, fungi, animal dander, and certain foods but may also be caused by chemical irritants in the atmosphere or by infections of the respiratory tract. Susceptibility to an asthma attack is based on hyperactivity of the bronchial muscles, which constrict on exposure to one or another of these agents. Episodes of asthma vary widely in severity and may last from a few minutes to several days.
They may begin at any age but usually occur in childhood. In children, asthma often is associated with eczema, a skin inflammation that may reflect the tendency of the child to develop hypersensitivity reactions. The attacks usually become less frequent and less severe over the years and disappear in about half of all affected children before adulthood. In one form of asthma, called intrinsic asthma, however, the attacks become less frequent and less severe, but recovery between them is less complete. The bronchi in such patients become chronically narrowed, causing a progressive loss of capacity for physical exertion. The prevalence of asthma is only about 1 or 2 percent worldwide but varies greatly from country to country.
In the United States, asthma affects about 6. 9 percent of children. Typically, an asthma attack begins within minutes after exposure to a triggering agent. Symptoms include a sensation of tightness in the chest, coughing and wheezing, and difficulty in breathing. Persons having attacks usually find it more difficult to exhale then inhale, which of the chest and impaired lung functions. The breathing difficulty is alleviated somewhat by leaning forward and supporting the trunk with the arms on some object.
Heliox is a mixture of oxygen and helium and is used in the management of different respiratory conditions. Although beneficial evidence in the use of heliox to manage acute exacerbation of asthma is conflicting and highly contested, recent reports as well as clinical trials have shown positive reports among certain patients. One important property of heliox is that it’s insoluble and biologically ...
Attacks that last several hours or more, even several days, despite treatment are called status asthmatic us. Patients with this condition develop a rapid pulse as the heart attempts to compensate for the lack of oxygen in the blood by beating faster. They also develop signs of exhaustion and dehydration. On along-term basis, asthma usually is managed by determining the agent responsible for the attacks so that the patient can avoid it. When avoidance of allergens is not feasible, patients can sometimes be desensitized by injections of graded doses of the allergen at regular intervals. Relaxation and breathing exercises have also been found helpful.
Most asthma attacks can be controlled by the administration of appropriate drugs by injection, orally, or by inhalation of aerosols. Occasionally, oxygen administration or use of a respirator maybe required. Asthma attacks can result in death. Peter L. Petra kis
Gershwin, M. E.
, and Klingelhofer, E. L. , Asthma (1986); Rud off, Carol, Asthma Resources Directory (1990); Sub ak-Sharpe, G. , Breathing Easy (1988); Young, Stuart, H. , et al. , The Asthma Handbook (1985)..