Wheezing and stridor.

Wheezes are defined as high-pitched, continuous, adventitious lung sounds. They are produced by oscillation of opposing airway walls whose lumen is narrowed. Although asthma is the most common cause of wheezing, a wide variety of disease processes may result in wheezing due to airway obstruction. This obstruction may be caused by airway edema, smooth muscle constriction, increased secretions, vascular congestion, mass lesions, scarring, or foreign bodies. Stridor is a special kind of wheeze described as a loud musical sound of constant pitch, which is heard in patients with tracheal or laryngeal obstruction. The full differential diagnosis of airway obstruction should be carefully considered in any patient with wheezing or stridor.