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  • Definition: Continuous high-pitched sound with musical quality emitting from the chest during expiration.
  • Patterns of wheezing (J Allergy Clin Immunol 2003;111(4):661): According to the Tucson children's respiratory study, a child who begins wheezing in the early years of life (<3 yr) can be classified into one of the following three phenotypes:
    1. Transient early wheezing (not associated with eczema, other atopy, or family hx of asthma)

      • Comprises 80% of children who wheeze during the first year of life and 60% of children during second year of life.
      • Wheezing episodes resolve by age 3 yr.
      • Risk factors include low infant pulmonary function, maternal smoking during pregnancy, younger mother.

    2. Non-atopic wheezing

      • Children who continue to wheeze beyond the third year of life after having an RSV or other viral LRI early in life.
      • RSV-LRI predisposes to lower lung function and more likely bronchodilator response.

    3. IgE-associated or atopic wheeze or asthma

      • Episodes more likely to continue beyond age 6 yr.
      • Associated with markers of atopy (high IgE, eosinophilia).
      • Family hx of asthma (especially in the mother), increased other atopy (eczema, rhinitis).
      • Lowest lung function at age 6 yr compared with other phenotypes.

  • Differential diagnosis: Modified asthma predictive index (API; J Allergy Clin Immunol 2004;114(6):1282): Identifies children with wheezing who are at risk for persistent asthma; requires h/o four or more episodes of childhood wheezing and one major and two minor criteria
  • See table below

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Age <5 Years

Age >5 Years

  • Asthma
  • Infection (viral upper or lower respiratory infections, bronchiolitis, tuberculosis, pertussis)
  • Bronchopulmonary dysplasia
  • Sinusitis
  • Foreign body aspiration
  • Anatomic abnormality (vascular ring, mediastinal mass)
  • Tracheobronchomalacia
  • Aspiration due to swallow dysfunction or GERD
  • Cardiac disease with congestive heart failure
  • Immunodeficiency, immotile cilia
  • CF
  • Asthma
  • Vocal cord dysfunction
  • GERD
  • CF
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Major Criteria

Minor Criteria

Parental history of asthma

Physician-diagnosed atopic dermatitis

Allergic sensitization to at least one aeroallergen

Allergic sensitization to eggs, milk, or peanuts

Wheezing apart from viral illness

Blood eosinophilia >4%


  • Definition: Chronic inflammatory disorder of the airways associated with airway hyperresponsiveness that leads to recurrent episodes of combinations of wheezing, breathlessness, chest tightness, or coughing. Usually associated with diffuse but variable airflow obstruction within the lung that is often reversible spontaneously or with treatment.
  • Pathophysiology: Combination of bronchial smooth muscle constriction and obstruction of the lumen (by inflammatory exudates and airway wall edema).


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Physical Exam

  • Age at onset of wheezing
  • Frequency, timing (day or night)
  • H/o prematurity, BPD
  • Use of urgent care ED visits, hospitalizations, need for O2 or intubation
  • Comorbid conditions: Eczema, allergies, chronic rhinitis, sinusitis, GERD
  • FHx of asthma and allergic conditions
  • Triggers for wheezing: URI or infection, exercise, cold air, allergens (eg, dust mite, animal dander, grass or tree pollen, molds, ...

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