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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 9–23)

  • The pathophysiology of asthma is heterogeneous, but a division into T2-high and T2-low endotypes (marked by high and low levels of classic Th2 cytokines, including IL-4, IL-5, and IL-13, respectively) has been shown to be important with regard to the selection of therapies

    • Allergic asthma falls into the T2-high endotype, as do late-onset T2-high asthma and aspirin/NSAID-associated respiratory disease (AERD)

    • T2-low asthma phenotypes include nonallergic asthma, which tends to occur in adults and be marked by neutrophilic inflammation and variable response to standard therapies

Table 9–23.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 9–5

  • Episodic wheezing, shortness of breath, chest tightness, and cough

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

  • Excess sputum production

  • Symptoms are ...

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