Chapter 25. Pulmonology

Wheezing

• 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

Asthma

• 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).

Diagnosis