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Rebecca Dezube

, MD, MHS, Johns Hopkins University

Last full review/revision Sep 2021| Content last modified Sep 2021
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Stridor is a gasping sound during inhalation resulting from a partial blockage of the throat (pharynx), voice box (larynx), or windpipe (trachea).

Stridor is usually loud enough to be heard at some distance. The sound is caused by turbulent airflow through a narrowed upper airway.

In children, the cause may be

In adults, the cause may be

When both vocal cords are paralyzed, the space between the paralyzed cords is very small, and the airway is inadequate so that even moderate exertion causes difficulty in breathing and a harsh, high-pitched sound (stridor) with each breath.

Brief episodes of stridor can result when a person inhales a food particle or bit of water into the lungs, causing contraction of the voice box (larynx). If an inhaled foreign object is a likely cause and the person is outside of a hospital, another person, if trained, can sometimes help expel the foreign object. For example, in an adult, the other person may use the Heimlich maneuver Choking Maneuvers to relieve choking are frequently life saving. Adults most often choke on a piece of food, such as a large piece of meat. Infants do not have well-developed swallowing reflexes and... read more .

If a person has stridor and is in a hospital or emergency department, a tube may be inserted through the person's mouth or nose (tracheal intubation) or through a small surgical incision directly into the trachea (tracheostomy) to allow air to get past the blockage and prevent suffocation.

The cause usually becomes clear during tracheal intubation, when the doctor can see the upper airway directly. If tracheal intubation is not done, the diagnosis is usually determined by inserting a flexible viewing tube through the nose and upper airway (a procedure called nasopharyngeal laryngoscopy).

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