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A 14-year-old girl with a history of asthma requiring daily inhaled corticosteroid therapy and allergies to house dust mites, cats, grasses, and ragweed presents to the emergency department in mid-September, reporting a recent “cold” complicated by worsening shortness of breath and audible inspiratory and expiratory wheezing. She appears frightened and refuses to lie down but is not cyanotic. Her pulse is 120 bpm, and respirations are 32/min. Her mother states that she has used her albuterol inhaler several times a day for the past 3 days and twice during the previous night. She took an additional two puffs on her way to the emergency department, but her mother states that “the inhaler didn’t seem to be helping so I told her not to take any more.” What emergency measures are indicated? How should her long-term management be altered?

A consistent increase in the prevalence of asthma over the past 60 years has made it an extraordinarily common disease. The reasons for this increase—most striking in people under 18 years of age and shared across all modern, “Westernized” societies—are poorly understood. The global estimate of the number of affected individuals is 300 million. In the United States alone, 17.7 million adults (7.4% of the population) and 6.3 million children (8.6% of the population) have asthma. The condition accounts for 10.5 million outpatient visits, 1.8 million emergency department visits, and 439,000 hospitalizations each year. Considering the disease’s prevalence, the annual mortality in the USA is low—around 3500 deaths—but many of these deaths are considered preventable, and the number has not changed much despite improvements in treatment.

The clinical features of asthma are recurrent episodes of shortness of breath, chest tightness, and wheezing, often associated with coughing. Its hallmark pathophysiologic features are widespread, reversible narrowing of the bronchial airways and a marked increase in bronchial responsiveness to inhaled stimuli. Its pathologic features are lymphocytic, eosinophilic inflammation of the bronchial mucosa. These changes are accompanied by “remodeling” of the bronchial wall, with thickening of the lamina reticularis beneath the epithelium and hyperplasia of the bronchial vasculature, smooth muscle, secretory glands, and goblet cells.

In mild asthma, symptoms occur only intermittently, as on exposure to allergens or airway irritants such as air pollution or tobacco smoke, on exercise, or after viral upper respiratory infection. More severe forms of asthma are associated with more frequent and severe symptoms, especially at night. Chronic airway constriction causes persistent respiratory impairment, punctuated by periodic asthma exacerbations marked by acute worsening of symptoms. These attacks are most often associated with viral respiratory infections and are characterized by severe airflow obstruction from intense contraction of airway smooth muscle, inspissation of mucus plugs in the airway lumen, and thickening of the bronchial mucosa from edema and inflammatory cell infiltration. The spectrum of asthma’s severity is wide, and patients are classified based on two domains: impairment and risk. Measures of impairment are ...

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