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Asthma Update: Pearls You May Have Missed

Asthma Update: Pearls You May Have Missed

A chronic inflammatory disease of the airways, asthma is one of the most common reasons why children are brought to a physician. There has been a significant worldwide increase in the prevalence of asthma--especially in developed countries.1 Asthma affects more than 26 million Americans: more than 9 million are younger than 18 years.2 Children make more than 2.7 million physician visits for asthma, and they miss more than 14 million school days per year.2 Fortunately, in 2000, deaths from asthma decreased for the first time in many years. Unfortunately, and despite our best efforts, more than 4000 people died of asthma- related complications in 2000. Among them were 233 children under 17 years of age.3

Pediatricians deal with asthma on a daily basis and must treat acute exacerbations; determine whether maintenance therapy is warranted; monitor the response to this therapy; and closely monitor the growth of the asthmatic child--especially the child taking corticosteroids.

In this article, we outline a treatment strategy for the acute asthma flare. We also discuss the most recent advances in pediatric drug therapy and provide up-to-date recommendations for the long-term management of asthma (Tables 1, 2, and 3).

PATHOPHYSIOLOGY

Asthma is the result of airway inflammation caused by infiltration of cells (mast cells, eosinophils, basophils, monocytes, lymphocytes) and mediators (IgE, cytokines, histamines, leukotrienes, prostanoids). Airway inflammation leads to edema, excess mucus production, and bronchial hyper-responsiveness and/or bronchospasm. This results in air trapping (hyperinflation), carbon dioxide retention, ventilation-perfusion mismatch, hypoxia, respiratory distress, and--in severe cases--respiratory failure. A genetic predisposition, an atopic diathesis, and certain environmental stimuli are the likely factors that predispose children to asthma. Asthma triggers include (but are not limited to) seasonal allergies, changes in weather, animals, tobacco smoke, upper respiratory tract infections, and exercise.

Some patients respond poorly to treatment with the available anti-inflammatory agents. This phenomenon is not fully understood but is probably the result of airway remodeling and associated non-reversible airflow obstruction.4 It is not clear whether airway remodeling is a consequence of chronic inflammation or whether these 2 processes occur in parallel.4 The hypothesis that early and aggressive treatment of asthma could decrease the risk of these long-term changes is currently under investigation.

EVALUATION

A detailed history is the key to accurate diagnosis; it is also crucial for characterizing the severity of asthma. The history should include a list and pattern of symptoms, precipitating and aggravating factors, and the number of emergency department visits and hospital and ICU admissions. It is important to note whether the child required intubation and ventilatory support (which is associated with increased mortality). Details about the family and social history, as well as about current treatment plans, also guide further interventions.

In the acutely ill child, monitor vital signs and check a pulse oximetry reading. Pay special attention to the respiration rate over a 1- to 2-minute period. Focus your physical examination on the signs and symptoms of respiratory distress, which include:

• Difficulty in speaking.

• Nasal flaring.

• Intercostal retractions.

• Use of accessory muscles of respiration.

• Poor air exchange.

• Wheezing.

Spirometry is helpful in evaluating the cooperative child but generally is not available in a pediatrician's office. Peak flow meters are a useful and readily available alternative. Using a chart based on the child's height, a predicted peak flow can be compared with the child's value before and after bronchodilator therapy. We have found that most children are able to perform this test appropriately by the time they are 6 years old. In infants, the diagnosis of asthma is based on the history, the physical examination findings, and response to bronchodilator therapy.

A chest radiograph is of limited value in the diagnosis of asthma but is very helpful in excluding other processes. Hyperinflation and peribronchial cuffing are typical findings in a child with asthma, although the same findings can be seen with viral respiratory infections, such as bronchiolitis (Figure). You might also consider obtaining additional studies, as suggested in an algorithm we have previously published for the evaluation of chronic cough.5 A pediatric allergist can help determine whether there are specific allergens that trigger the patient's asthma. Exclusion of these triggers can significantly decrease the patient's symptoms.

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