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INTRODUCTION

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CASE STUDY

A 10-year-old girl with a history of poorly controlled asthma presents to the emergency department with severe shortness of breath and audible inspiratory and expiratory wheezing. She is pale, refuses to lie down, and appears extremely frightened. Her pulse is 120 bpm and respirations 32/min. Her mother states that the girl has just recovered from a mild case of flu and had seemed comfortable until this afternoon. The girl uses an inhaler (albuterol) but “only when really needed” because her parents are afraid that she will become too dependent on medication. She administered two puffs from her inhaler just before coming to the hospital, but “the inhaler doesn’t seem to have helped.” What emergency measures are indicated? How should her long-term management be altered?

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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—shared across all modern, “westernized” societies—are poorly understood, but in the United States alone, 18.9 million adults and 7.1 million children currently have asthma. The condition accounts for 15 million outpatient visits, 1.8 million emergency department visits, and 440,000 hospitalizations each year. Despite substantial improvements in the treatment for the disease, asthma still accounts for 3400 deaths per year in the USA.

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The clinical features of asthma are recurrent bouts of shortness of breath, chest tightness, and wheezing, often associated with coughing. Its hallmark physiologic features are widespread, reversible narrowing of the bronchial airways and a marked increase in bronchial responsiveness to inhaled stimuli; and 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.

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In mild asthma, symptoms occur only intermittently, as on exposure to allergens or air pollutants, 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 frequent acute asthmatic attacks, or “asthma exacerbations.” 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 as having “mild intermittent,” “mild persistent,” “moderate persistent,” and “severe persistent,” either based on the frequency and severity of symptoms and the severity of airflow obstruction on pulmonary function testing or by the minimal medical therapy required to keep their asthma well-controlled, and as “exacerbation-prone” or “exacerbation-resistant” based on the frequency of asthma exacerbations.

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Until recently, the entire range of asthma severity was regarded as eminently treatable, because treatments for quick relief ...

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