Asthma is a chronic inflammatory disorder of the airways that characterized by variable and recurring symptoms, airflow obstruction, bronchial hyperresponsiveness, and inflammation1,2. It is one of the most common chronic disease in children. Signs and symptoms of asthma include chest tightness, wheezing/whistling, shortness of breath, and coughing, especially at night and early in the morning. The interval between episodes can vary from days, weeks, to months. It relates to trigger exposure, which can be respiratory infections, allergens, exercise, stress and tobacco smoke.
Two main factors that lead to the development asthma are genetic predisposition and environmental exposure1,2. An acute inflammation occurs when bronchial smooth muscle contracts (bronchoconstriction) quickly to narrow the airways in reponse to allergens or irritants. Allergen-induced acute bronchoconstriction is caused by immunoglobulin E (IgE) dependent release of mediators and cytokines in the airway. This leads to airway inflammation. Chronic response contributes to permanent airway remodeling (i.e. hypertrophy of bronchial smooth muscle, increased mucus production, thickening of sub-basement membrane). The change in airway structure leads to persistent airway obstruction, reduced forced expiratory volume in one second (FEV1) and chronic symptoms (i.e. wheezing, coughing at night, shortness of breath, chest tightness and pain).
Diagnosis of asthma includes symptoms occurring with a particular time of the year or substance (i.e. dust, perfume, animal), presence of eczema and allergic rhinitis, improvement in FEV1 (more than 12% increased from baseline) with albuterol, challenges with exercise or substance as listed earlier, and elevated serum IgE or eosinophils1,2. Spirometry is a pulmonary function test that is performed at the initial assessment and used to measure the FEV1 in six seconds before and after the patient inhales a short-acting bronchodilator (i.e. albuterol). This test determines if there is airflow obstruction, its severity, and if it is reversible by the short-acting bronchodilator over the short term. An increase of FEV1 by more than 12% in one second from the baseline or an average daily peak expiratory flow (PEF) rate variability of great than 10% after short-acting bronchodilator use, indicates bronchodilator reversibility. Diagnosis of asthma is not black or white, and there is no single diagnostic test. Not every patient has to present all of the aforementioned symptoms.
Asthma is classified based on "impairment" in lung function and lifestyle, and the "risk" of exacerbation. Classification of the severity of asthma is important in selecting the appropriate pharmacologic treatment and determining how aggressive initial therapy should be. Asthma with airway remodeling is more difficult to treat.
The tables below can be used to assess impairment and risk of exacerbation severities and determine the initial treatment step in patients who are not taking long-term controlled asthma medications.
The goals of pharmacotherapy are to prevent symptoms and the need for ...