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According to the National Health Interview Survey (NHIS), asthma prevalence rates in the United States are 7.3% in adults and 9.3% in children. This equates to $16.1 billon in indirect and direct expenses associated with asthma according to the American Lung Association Epidemiology and Statistics Unit Research Program. In the pediatric population males are more likely to report current asthma symptoms and in the adult population females are more likely to report the presence of asthma.1 Evaluation of national surveillance data within a 3 year time period revealed 12.3 million physician visits, 1.3 million outpatient department visits within hospital systems, 1.8 million emergency department visits, and 4210 deaths attributed to asthma.2 The rate of a health care encounter for asthma does not differ by race. When evaluating race in regard to health care settings, whites tend to utilize physician offices, whereas blacks have higher rates for hospital-based sites for asthma management.

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Pathophysiology

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The major characteristics of asthma are airway inflammation and bronchial hyper-responsiveness which cause variable degree of airflow obstruction.3 In the asthmatic response, a genetically predisposed or atopic individual is exposed to a specific reactive stimuli or trigger. The most common asthma triggers are to molds, pollen, animal dander, and dust mites. Minutes after repeated exposure, the immediate asthmatic response occurs causing bronchoconstriction which resolves spontaneously or easily by β2-agonist use. Within 4 to 12 hours after the immediate asthmatic response, the late asthmatic response, caused by influx of inflammatory cells primarily eosinophils, Th2 lymphocytes, mast cells, macrophages, and mediators such as leukotrienes, histamine, and prostaglandin infiltrate the airway. The reaction is often more severe and prolonged and is referred to as an asthma exacerbation. This chronic inflammation is postulated to cause hypertrophy and hyperplasia of the bronchial smooth muscle and mucus glands which may lead to permanent, irreversible obstruction termed airway remodeling.4 The combination of airway obstruction and inflammation leads to the common symptoms of asthma which are cough, wheezing, chest tightness, and dyspnea.5 Among children, nighttime cough may be the only symptom present.6

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Diagnosis and Assessment of Control

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Diagnosis is based on a thorough history with special focus on symptoms and genetic predisposition. The definitive diagnosis is made through the use of spirometry. This is a diagnostic test where a person exhales forcefully into a machine to determine if airflow obstruction is present. To determine if obstruction is present the ratio of the forced expiratory volume in 1 second (FEV1) over forced vital capacity (FVC) is reviewed. (Table 43-1) To determine reversibility, as in asthma, a short-acting β-agonist (albuterol) is given and the post-bronchodilator FEV1 is evaluated. If the FEV1 improves greater or equal to 12% and 200 mL when compared to prebronchodilator value the person is diagnosed with asthma.7 Once diagnosis is made, further age-specific evaluation based on impairment and risk is ...

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