Wheeze

Wheeze is a musical breath sound, usually expiratory, produced by turbulent airflow through narrowed lower airways. It is most commonly associated with bronchospasm (as in asthma or reactive airway disease) but can result from any process that narrows the airways below the vocal cords.

Common causes of wheezing:

• Bronchospasm — smooth muscle contraction in the bronchial walls, as in acute asthma, COPD exacerbation, or anaphylaxis
• Mucosal edema — swelling of the airway lining from inflammation or allergic reaction
• Mucus plugging — excessive secretions partially obstructing airway lumens
• Foreign body — lodged in a bronchus, producing localized wheeze (unilateral wheezing is a red flag for foreign body aspiration)

The clinical interpretation of wheeze requires attention to several features:

• Timing — expiratory wheeze is typical of bronchospasm; inspiratory wheeze may indicate more severe obstruction or a different mechanism
• Distribution — diffuse bilateral wheeze suggests a systemic process (asthma, COPD); localized or unilateral wheeze suggests a focal obstruction (foreign body, tumor, mucus plug)
• Severity — the absence of wheeze in a patient with severe respiratory distress can indicate airflow so reduced that turbulence cannot be generated (“silent chest”), which is more dangerous than loud wheezing

Wheeze should be distinguished from stridor, which is typically inspiratory and indicates upper-airway narrowing. Both represent turbulent airflow through a narrowed passage, but stridor localizes the problem above the vocal cords while wheeze localizes it below.

Treatment depends on the underlying cause. Bronchospasm responds to bronchodilators (beta-agonists such as albuterol) and, in severe cases, systemic corticosteroids and epinephrine. Foreign body obstruction may require bronchoscopic removal. The sound itself is a sign, not a target — treating the wheeze means treating its cause.

Related terms

• Stridor — upper-airway narrowing sound
• Airway — the passage whose narrowing produces wheeze
• Ventilation — the process that lower-airway narrowing impedes