What could stridor indicate during a respiratory examination?

Stridor is a specific, high-pitched breathing sound that is typically associated with upper airway obstruction. This sound is generated when airflow passes through a narrowed or obstructed airway, most commonly occurring in the larynx or the trachea. It is often heard during inspiration and may indicate conditions such as croup, laryngitis, foreign body aspiration, or anaphylaxis, all of which involve a degree of obstruction in the upper airway.

In contrast, the other options do not align with the characteristics of stridor. Middle airway obstruction would not typically produce stridor; instead, it may cause different respiratory sounds. Fluid retention in the lungs primarily leads to crackles or wheezes rather than stridor, as it relates to lower airway issues, such as pulmonary edema. Similarly, collapsed alveoli, or atelectasis, predominantly results in diminished breath sounds or dullness rather than stridor, which again emphasizes the distinction that stridor is fundamentally linked to problems in the upper airway.