Severe asthma is a serious health concern that can lead to respiratory failure and death.
Asthma kills an estimated 5,000 persons a year in the United States and as many as 470,000 persons seek hospital treatment for their asthma symptoms. Despite its prevalence, experts differ in their definitions of the disease. Clinical authorities typically favor a broad, comprehensive definition. Other authorities believe asthma is not a single disease, but an entire group of closely related diseases with a common clinical picture. In general, however, all agree that asthma is a condition in which the bronchial tubes in the lungs react to different stimuli by becoming inflamed.