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Definition of the Complaint

Noisy breathing in infants is a common presenting complaint. The first step toward formulating a differential diagnosis is to characterize the type of sound heard. Stertor, a low-pitched rattling inspiratory noise, is caused by obstruction of airway above the level of the larynx. It is frequently heard in infants with nasal congestion and is often of little consequence. Stridor, a harsh, high-pitched respiratory sound typically heard on inspiration, often indicates laryngeal obstruction. Wheezing, a musical sound heard on expiration, is caused by partial obstruction of the lower airway. In young children, sometimes expiratory noises cannot be easily distinguished from inspiratory ones, and at times both may be present. Among these causes of noisy breathing, wheezing is the most common of clinical significance.

Complaint by Cause and Frequency

The causes of wheezing in childhood vary by age (Table 1-1) and may also be grouped in categories based on the following criteria: (1) Anatomic (extrinsic or intrinsic to the airway), (2) Inflammatory/ Infectious, (3) Genetic/Metabolic, or (4) Miscellaneous causes (Table 1-2).

Table 1-1. Causes of Wheezing in Childhood by Age.
Table 1-2. Causes of Wheezing in Childhood by Mechanism.

Clarifying Questions

A thorough study of the child’s history is essential to arrive at an accurate diagnosis in a child who presents with wheezing. Consideration of age at onset, course and pattern of illness, and associated clinical features provides a useful framework for creating a differential diagnosis. The following questions may help provide clues to the diagnosis:

  • What was the age at onset of wheezing?
    • Onset at ...

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