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For further information, see CMDT Part 9-05: Asthma

Key Features

Essentials of Diagnosis

  • Episodic or chronic symptoms of wheezing, dyspnea, and cough

  • Symptoms frequently worse at night or in the early morning

  • Prolonged expiration and diffuse wheezes on physical examination

  • Limitation of airflow on pulmonary function testing or positive bronchoprovocation challenge

  • Reversibility of airflow obstruction, either spontaneously or following bronchodilator therapy

General Considerations

  • A chronic disorder of the airways characterized by

    • Variable airway obstruction

    • Airway hyperresponsiveness

    • Airway inflammation

  • Common aeroallergens

    • Dust mites

    • Cockroaches

    • Cats

    • Pollen

  • Nonspecific precipitants

    • Exercise

    • Respiratory tract infections, especially viral

    • Rhinosinusitis

    • Postnasal drip

    • Aspiration

    • Gastroesophageal reflux

    • Changes in weather

    • Stress

  • Tobacco increases symptoms and decreases lung function

  • Certain medications (including aspirin and nonsteroidal anti-inflammatory drugs) may be triggers (Table 9–24)

Table 9–24.Pulmonary manifestations of selected medication toxicities.


  • Affects 8–10% of the population in the United States

  • Accounts for 10 million office visits, 1.8 million emergency department visits, and more than 3500 deaths annually in the United States

  • Slightly more common in boys (< 14 years old) and in women

  • Hospitalization rates have been highest among blacks and children

  • Death rates for asthma are consistently highest among blacks aged 15–24 years

Clinical Findings

Symptoms and Signs

  • See Table 9–2

  • Episodic wheezing and difficulty breathing, chest tightness, and cough

  • Asthma symptoms may occur spontaneously or be precipitated or exacerbated by many different triggers

  • Excess sputum production

  • Symptoms are frequently worse at night

  • Frequency of symptoms is highly variable

    • Some patients have infrequent, brief attacks

    • Others may suffer nearly continuous symptoms

  • Nasal findings consistent with allergy and evidence of allergic skin disorders

  • Wheezing with normal breathing or a prolonged forced expiratory phase

Table 9–2.Evaluation and classification of severity of asthma exacerbations.

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