Stridor

What stridor sounds like

Stridor is a loud, harsh, musical sound, sometimes like a crow or a seal, heard without a stethoscope. It is caused by turbulent air in a narrowed airway. Where it is heard in the breathing cycle helps locate the narrowing:

Stridor vs wheezing

Wheezing is a softer, musical whistle, usually on breathing out, from narrowed small airways in the lungs, as in asthma or bronchiolitis. Stridor is louder, harsher, and usually on breathing in, from the throat or windpipe. The difference matters because asthma inhalers do not treat stridor.

Causes of stridor in children

Children's airways are narrow, so a small amount of swelling causes a big reduction in airflow.

• Croup: the most common cause, in children aged 6 months to 3 years. A viral infection swells the area below the vocal cords. Barking, seal-like cough, hoarse voice and stridor, worse at night. Usually mild and treated with a single dose of steroid.
• Laryngomalacia: the most common cause of stridor in babies. Floppy tissue above the voice box collapses inward when breathing in. Noisy breathing starts in the first weeks, is worse when feeding, crying or lying on the back, and usually resolves by 12 to 24 months.
• Inhaled foreign object: sudden choking, coughing and stridor, often in toddlers who were eating nuts, grapes or playing with small toys. See foreign body in the throat.
• Epiglottitis: a bacterial infection of the epiglottis, now rare because of the Hib vaccine. High fever, drooling, severe sore throat, tripod sitting and soft stridor. Life-threatening.
• Bacterial tracheitis: a severe infection of the windpipe, often following croup, with high fever and a toxic appearance.
• Anaphylaxis: throat swelling from an allergic reaction.
• Subglottic stenosis and vascular rings: structural problems present from birth or after prolonged breathing tubes.
• Retropharyngeal or peritonsillar abscess: neck pain, fever, drooling.

Causes of stridor in adults

• Anaphylaxis and angioedema: sudden swelling of the throat, tongue or lips from allergies or medicines such as ACE inhibitors.
• Epiglottitis: now seen more in adults than children. Severe sore throat and painful swallowing with a near-normal-looking throat.
• Vocal cord paralysis: after thyroid or chest surgery, or from nerve compression. Paralysis of both cords causes stridor.
• Vocal cord dysfunction: the cords close when they should open, causing episodes of throat tightness and stridor, often mistaken for asthma.
• Narrowing after intubation or tracheostomy.
• Tumors of the larynx, trachea or thyroid, causing gradually worsening stridor with hoarseness or swallowing difficulty.
• Neck trauma, burns and smoke inhalation.
• Inhaled foreign bodies, especially in older adults with swallowing problems.

How stridor is diagnosed

Doctors first check how severe the breathing difficulty is: breathing rate, chest and neck retractions, oxygen levels, alertness and color. They avoid examining the throat with a tongue depressor if epiglottitis is suspected, because upsetting the patient can trigger complete obstruction.

When stable, tests may include:

• Flexible laryngoscopy: a thin camera through the nose to look at the voice box
• Neck and chest X-rays
• CT scan of the neck and chest
• Bronchoscopy to find and remove an inhaled object, done under anesthesia
• Allergy testing after an allergic reaction

Treatment

• Croup: a single dose of dexamethasone, and nebulized epinephrine for moderate to severe cases. Keep the child calm. Cool night air may comfort them, though evidence for humidity is weak.
• Anaphylaxis: intramuscular epinephrine immediately, then emergency care.
• Epiglottitis: securing the airway in an operating room or ICU, plus intravenous antibiotics.
• Foreign body: removal by bronchoscopy. For a choking person who cannot breathe, cough or speak, give back blows and abdominal thrusts (chest thrusts for infants under 1 year) and call 911.
• Laryngomalacia: usually observation. Treating reflux may help. Surgery (supraglottoplasty) is used for severe cases with feeding or breathing problems.
• Structural narrowing and tumors: dilation, laser or surgical treatment.

What to do while waiting for help

• Keep the person calm and upright, in the position they find most comfortable.
• Do not try to look in the throat or put fingers in the mouth unless you can see an object.
• Do not force a child to lie down or drink.
• Use their epinephrine auto-injector for a known severe allergy.

Frequently asked questions

What is stridor?

Stridor is a harsh, high-pitched sound produced when air flows through a narrowed upper airway, such as the voice box or windpipe. It is usually heard when breathing in. It is a sign, not a diagnosis, and can be caused by croup, swelling, infection, an inhaled object or structural problems.

Is stridor an emergency?

Stridor always needs prompt medical assessment. It is an emergency when it starts suddenly, occurs at rest, or comes with struggling to breathe, drooling, trouble swallowing, blue lips, drowsiness, or signs of an allergic reaction. Call 911 or your local emergency number.

What is the difference between stridor and wheezing?

Stridor is a loud, harsh sound mostly on breathing in, from the throat or upper windpipe. Wheezing is a softer, musical whistle mostly on breathing out, from narrowed airways in the lungs, as in asthma. They have different causes and treatments.

What causes stridor in babies?

The most common cause is laryngomalacia, floppy tissue above the voice box that collapses with breathing. It causes noisy breathing that worsens with feeding and crying and usually improves by age 1 to 2. Croup, infections, structural narrowing and inhaled objects are other causes.

How is croup stridor treated?

Most children with croup receive a single dose of an oral steroid (dexamethasone), which reduces swelling within hours. Children with stridor at rest may also need nebulized epinephrine in the ER and observation. Keeping the child calm helps, because crying worsens stridor.