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A systematic review of the literature was performed and included the Cochrane database, PubMed, UpToDate®, the National Heart, Lung, and Blood Institute and Global Initiative for Asthma Web Sites, and the National Institute of Health’s National Asthma Education and Prevention Program (NAEPP) Expert Panel documents. Much of the contents of this chapter are available online at www.nhlbi.nih.gov and www.ginasthma.com.

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Asthma is a chronic inflammatory disease of the airways affecting 20 million Americans. Despite continuing research and development of new drugs, asthma is responsible for approximately 500000 hospitalizations per year and between 5000 and 6000 deaths per year. It is the third leading cause of preventable hospitalizations in the United States. The incidence and prevalence of this disease are rising for a variety of reasons.

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This is a complex disease with both genetic and environmental contributors. There are a variety of asthma phenotypes in susceptible individuals, for example, exercise-induced asthma, cough-variant asthma, nocturnal asthma, and a spectrum of mild to severe disease. The underlying problem is inflammation of the airways and airway hyperresponsiveness mediated by substances produced by many different cells (eosinophils, neutrophils, epithelial cells).1–4 Environmental factors such as viral infections, irritants, aeroallergens, and stress can precipitate exacerbations in the inflamed airway. The principal clinical consequence of this acute and chronic inflammation is the development of asthma exacerbations, characterized by bronchial smooth-muscle contraction, increased mucus secretion and mucosal edema with desquamation of airway epithelium.1,2 Exacerbations of asthma are an important clinical marker of disease control and progression. Exacerbations are probably the most important outcome from a humanistic and health economics viewpoint. Thirty-seven percent of the total costs for asthma, $2.7 billion, resulted from medical care of severe acute exacerbations.5 The National Institutes of Health’s NAEPP and the Global Initiative for Asthma have provided guidelines and resources for optimal asthma management, the most recent of which were evidence-based.3,4 Since primary care providers deal with the vast majority of asthma patients, it is vital that they recognize and appropriately manage asthma in both the chronic-maintenance phase as well as the acute-exacerbation phase.

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Patients may present with recurrent episodes of wheezing, chest tightness, difficulty breathing, and cough at any age; the majority of patients with asthma are diagnosed during childhood (about 80%).2,3,4 Epidemiological studies of children with asthma in many populations reveal that approximately one-third have symptoms only during childhood, one-third have a period of quiescence during adolescence and then have return of their symptoms later in life, and one-third have unremitting symptoms. Adult-onset asthma is less likely to remit. Although the diagnosis is clinical, it can be challenging; not all that wheezes is asthma. Table 8-1 outlines the key indicators for the diagnosis of asthma. A personal or family history of atopy, eczema, or allergic rhinitis, although not a key indicator, is often associated with asthma.

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