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Kelly HW, Sorkness CA. Asthma. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7975293. Accessed July 6, 2012.

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  • Chronic inflammatory disorder of airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing.

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  • Major characteristics:
    • Airflow obstruction (related to bronchospasm, edema, and hypersecretion)
    • Bronchial hyperresponsiveness (BHR)
    • Airway inflammation
  • Inhaled allergen causes activation of B lymphocytes, mast cells, and macrophages, which release proinflammatory mediators such as histamine and eicosanoids that induce contraction of airway smooth muscle, mucus secretion, vasodilation, exudation, and edema with reduced mucus clearance.
  • Activation of eosinophils, T lymphocytes, basophils, neutrophils, and macrophages cause further release of inflammatory mediators such as leukotrienes, interleukins, histamine, platelet-activating factor (PAF), and chemotactic factors.

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  • Affects 22.9 million persons in the United States.
  • Most common chronic childhood disease, affecting approximately 6.7 million children.
  • Accounts for 1.6% of ambulatory care visits (10.6 million physician office visits and 1.2 million hospital outpatient visits).
  • Resulted in 440,000 hospitalizations and 1.7 million emergency department (ED) visits in 2006.
  • Accounts for >12.8 million missed school days per year.

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  • Genetic predisposition
  • Socioeconomic status
  • Exposure to secondhand tobacco smoke in infancy and in utero
  • Allergen exposure
  • Urbanization
  • Respiratory syncytial virus infection
  • Decreased exposure to common childhood infectious agents

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Signs and Symptoms

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  • Chronic asthma
    • Symptoms: Episodic dyspnea with wheezing, chest tightness, and coughing that may occur spontaneously, with exercise, or after exposure to known allergens
    • Signs: Expiratory wheezing; dry, hacking cough; atopy (e.g., allergic rhinitis, eczema)
    • Can vary in frequency from intermittent to chronic daily symptoms.
    • Severity determined by lung function, symptoms, nighttime awakenings, and interference with normal activity.
  • Acute severe asthma
    • Symptoms: Anxiousness with acute distress and complaints of severe dyspnea, shortness of breath, and chest tightness unresponsive to usual measures
    • Signs: Expiratory and inspiratory wheezing; dry, hacking cough; tachypnea; tachycardia; pallor or cyanosis; hyperinflated chest with intercostal and supraclavicular retractions

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Means of Confirmation and Diagnosis

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  • Chronic asthma
    • History of recurrent episodes of coughing, wheezing, chest tightness, or shortness of breath and confirmatory spirometry.
    • May be family history of allergy or asthma, or patient symptoms of allergic rhinitis.
    • History of exercise or cold air precipitating symptoms during specific allergen seasons.
  • Acute severe asthma
    • History of previous asthma exacerbations (e.g., hospitalizations, intubations) and complicating illnesses (e.g., cardiac disease, diabetes).
    • Assess hydration status; use of accessory muscles of respiration; and presence of cyanosis, pneumonia, pneumothorax, pneumomediastinum, and upper airway obstruction.

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Laboratory Tests

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  • Obtain complete blood count (CBC) when fever or purulent sputum present.
  • In acute severe asthma, arterial blood gases may reveal metabolic acidosis and low partial pressure of oxygen (PaO2).

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Imaging

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  • Chest radiography in patients with fever to rule ...

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