What can cause stridor?

Stridor is a high-pitched, wheezing sound often associated with difficulty in breathing and is specifically indicative of an obstruction in the upper airway. The primary causes of stridor include any condition that constricts or obstructs the airflow in the larynx or trachea. When the windpipe or larynx is obstructed, the airflow becomes turbulent, leading to the characteristic sound of stridor.

This condition can arise from several factors such as infections (like croup), foreign body aspiration, swelling due to allergic reactions, or trauma to the neck. Each of these factors directly influences the airflow in the upper airway, causing the stridor sound when the individual breathes.

Other options, while they relate to airway issues, involve different areas of the respiratory system and typically do not produce stridor. For instance, lower airway obstructions affect the bronchi and bronchioles, while fluid in the alveoli is more associated with conditions like pulmonary edema, and narrowing of the bronchi can lead to wheezing rather than stridor.