Definition of Asthma
Risk Factors for Asthma
The Natural History of Asthma
Clinical Features of Asthma
The Treatment of Asthma
Understand the epidemiology of asthma and the contributions of genetic predisposition and environmental factors.
Learn the pathology and pathophysiology of asthma and the importance of inflammatory mechanisms of this disease.
Appreciate the risk factors for asthma and the causes of exacerbation of symptoms.
Be able to objectively and accurately diagnose this disease.
Learn the strategies of treating asthma based on the National Institutes of Health guidelines.
Asthma is an episodic disease that is caused by widespread inflammation of the airways resulting from a complex interaction of cells, mediators, and cytokines. The typical symptoms—wheezing, shortness of breath and cough—may be provoked by environmental irritants and respiratory viruses. The acute symptoms of asthma are caused by airway contraction. Persistent inflammation can result in hypertrophy and hyperplasia of smooth muscle, microvascular leakage, activation of airway neurons, stimulation of mucus-secreting cells, disruption of the ciliated epithelium, and collagen deposition. There are three cardinal physiologic features of asthma: (1) diffuse airflow obstruction in both large and small airways; (2) reversibility of the airflow obstruction, either spontaneously or in response to therapy; and (3) bronchial hyperresponsiveness that can be described as an exaggerated bronchoconstrictive response by the airways to a variety of stimuli. Spirometry is most useful for diagnosis and monitoring the disease. Reversing airway obstruction with an inhaled short-acting bronchodilator is helpful in confirming the diagnosis. Bronchoprovocation testing to induce airflow obstruction also is helpful in the diagnosis of asthma. A negative test rules out asthma and a positive test is supportive. There are both short-term and long-term therapeutic objectives for every asthmatic patient. The short-term objective is the reversal of immediate symptoms. Long-term objectives are those directed at improving asthma control, including symptoms, effects on the quality of daily living, and use of rescue medication, and also preventing future exacerbations. Treatment protocols use step-care pharmacologic therapy based on asthma symptoms and the clinical response.