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 taking in a breath.

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:

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

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, the health care provider will check the person's temperature, pulse, breathing rate, blood pressure, and may need to do the Heimlich maneuver.

A breathing tube may be needed if the person can't breathe properly.

After the person is stable, the health care worker ask questions about the patient's medical history, and perform physical exam. This includes listening to the lungs.

Parents or caregivers may be asked the following medical history questions:

• Is the abnormal breathing a high-pitched sound?
• Did the breathing problem start suddenly?
• Could the child have put something in the mouth?
• 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 does the child have? (For example, nasal flaring or bluish color to the skin, lips, or nails)
• Is the child using chest muscles to breathe (intercostal retractions)?

Tests that may be done include:

• Arterial blood gas analysis
• Bronchoscopy
• CT scan, thoracic
• Laryngoscopy (examination of the voice box)
• Pulse oximetry to measure blood oxygen level
• X-ray of the chest or neck

Sobol SE . Epiglottis and croup. Otolaryngol Clin North Am. June 2008; 41(3); 551-566.