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.
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
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
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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