Stridor is an abnormal, high-pitched, musical breathing sound caused by a blockage in the throat or voice box (larynx). It is usually heard when breathing in.

See also: Wheezing

Children are at higher risk of airway blockage because they have narrower airways than adults. In young children, stridor is a sign of airway blockage and must be treated right away to prevent total airway obstruction.

The airway can be blocked by an object, swelling of the tissues of the throat or upper airway, or spasm of the airway muscles or the vocal cords.

Common causes of stridor include:

• Inhaling an object such as a peanut or marble (foreign body aspiration)
• Laryngitis (acute)
• Airway trauma
• Allergic reaction
• Croup
• Enlarged tonsils or adenoids (such as with tonsillitis)
• Abscess on the tonsils
• Inhalation injury (such as smoke inhalation)
• Neck surgery
• Swelling of the neck or face
• Secretions such as phlegm (sputum)
• Vocal cord cancer
• Assisted breathing with a tube (intubation) for a long period of time
• Diagnostic tests such as bronchoscopy or laryngoscopy

Follow your doctor's advice to treat the cause of the problem.

See also: Choking

Stridor may be a sign of an emergency. Call your health care provider right away if there is unexplained stridor, especially in a child.

In an emergency, a health care worker will check vital signs (temperature, pulse, breathing rate, blood pressure), and may need to do the Heimlich maneuver. Then the health care worker will take a medical history, and will do a physical examination. The physical exam will include monitoring the vital signs and listening to the lungs.

A breathing tube (intubation) may be needed if the person can't breathe properly (respiratory failure).

Medical history questions might include:

• Is the abnormal breathing a high-pitched sound?
• Did it begin suddenly?
• Is it possible that the child may have put something in the mouth and gotten it into the windpipe?
• Has the child been ill recently?
• Is the child's neck or face swollen?
• Has the child been coughing or complaining of a sore throat?
• What other symptoms are present?
• Is there nasal flaring?
• Is the child using chest muscles to breathe (intercostal retractions)?
• Does the child have blue lips, blue nailbeds, or a bluish color to the skin?

Diagnostic tests that may be done include:

• Arterial blood gas analysis
• Using a scope to look directly at the airway (bronchoscopy)
• CT scan, thoracic
• Laryngoscopy
• X-ray of the chest or neck