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Related to stridor: croup




Stridor is a term used to describe noisy breathing in general, and to refer specifically to a high-pitched crowing sound associated with croup, respiratory infection, and airway obstruction.


Stridor occurs when erratic air currents attempt to force their way through breathing passages narrowed by:
Stridor can usually be heard from a distance but is sometimes audible only during deep breathing. Someone who has stridor may crow and wheeze when:
  • inhaling
  • exhaling
  • inhaling and exhaling
Most common in young children, whose naturally small airways are easily obstructed, stridor can be a symptom of a life-threatening respiratory emergency.

Causes and symptoms

During childhood, stridor is usually caused by infection of the cartilage flap (epiglottis) that covers the opening of the windpipe to prevent choking during swallowing. It can also be caused by a toy or other tiny object the child has tried to swallow.
Laryngomalacia is a common cause of a rapid, low-pitched form of stridor that may be heard when a baby inhales. This harmless condition does not require medical attention. It usually disappears by the time the child is 18 months old.
The most common causes of stridor in adults are:
  • abscess or swelling of the upper airway
  • paralysis or malfunction of the vocal cords
  • tumor.
Other common causes of stridor include:
  • enlargement of the thyroid gland (goiter)
  • swelling of the voice box (largyngeal edema)
  • narrowing of the windpipe (tracheal stenosis)
When stridor is caused by a condition that slowly narrows the airway, crowing and wheezing may not develop until the obstruction has become severe.


When stridor is present in a newborn, pediatricians and neonatologists look for evidence of:
  • heart defects inherent at birth (congenital)
  • neurological disorders
  • General toxicity.
If examinations do not reveal the reasons for the baby's noisy breathing, the air passages are assumed to be the cause of the problem.
Listening to an older child or adult breathe usually enables pediatricians, family physicians, and pulmonary specialists to estimate where an airway obstruction is located. The extent of the obstruction can be calculated by assessing the patient's:
  • complexion
  • chest movements
  • breathing rate
  • level of consciousness
X rays and direct examination of the voice box (larynx) and breathing passages indicate the exact location of the obstruction or inflammation. Flow-volume loops and pulse oximetry are diagnostic tools used to measure how much air flows through the breathing passages, and how much oxygen those passages contain.
Pulmonary function tests may also be performed.


The cause of this condition determines the way it is treated.
Life-threatening emergencies may require:
  • the insertion of a breathing tube through the mouth and nose (tracheal intubation)
  • the insertion of a breathing tube directly into the windpipe (tracheostomy)



Berkow, Robert, editor. The Merck Manual of Medical Information: Home Edition. Whitehouse Station, NJ: Merck & Co., Inc., 1997.


a shrill, harsh sound, especially the respiratory sound heard during inhalation with a laryngeal obstruction. adj., adj strid´ulous.
laryngeal stridor that due to laryngeal obstruction. A congenital form, marked by stridor and dyspnea, is due to an infolding of a congenitally flabby epiglottis and aryepiglottic folds during inspiration; it is usually outgrown by two years of age.


A high-pitched, noisy respiration, like the blowing of the wind; a sign of respiratory obstruction, especially in the trachea or larynx.
[L. a harsh, creaking sound]


/stri·dor/ (stri´dor) [L.] a harsh, high-pitched breath sound.strid´ulous
laryngeal stridor  that due to laryngeal obstruction. A congenital form with dyspnea is due to infolding of a congenitally flabby epiglottis and aryepiglottic folds during inhalation; it is usually outgrown by two years of age.


(strī′dər, -dôr′)
1. A harsh, shrill, grating, or creaking sound.
2. Medicine A harsh, high-pitched sound in inhalation or exhalation.


Etymology: L, harsh sound
an abnormal high-pitched musical sound caused by an obstruction in the trachea or larynx. It is usually heard during inspiration. Stridor may indicate several neoplastic or inflammatory conditions, including glottic edema, asthma, diphtheria, laryngospasm, and papilloma.


ENT A harsh medium- to high-pitched crowing heard when breathing, especially on inspiration, due to an airway obstruction in the larynx or trachea; in children, stridor may occur in a background of congenital laryngeal stridor–laryngomalacia, which usually improves with age, or persists or recurs due to allergies, URIs, papillomas, foreign bodies, mediastinal masses, cysts of lung parenchyma


A high-pitched, noisy respiration, like the blowing of the wind; a sign of respiratory obstruction, especially in the trachea or larynx.
[L. a harsh, creaking sound]


Noisy breathing caused by narrowing or partial obstruction of the LARYNX or TRACHEA.


high-pitched, noisy respiration associated with respiratory obstruction, e.g. asthma; laryngeal oedema (e.g. in anaphylaxis)

stridor (strīˑ·dr),

n an abnormal, high-pitched, whistling sound heard during inspiration due to a blockage in the larynx or trachea. The condition may indicate inflammatory and neoplastic conditions, such as asthma, glottic edema, laryngospasm, diphtheria, papilloma, or other causes of swelling or laxity.


A high-pitched, noisy respiration; sign of respiratory obstruction.
[L. a harsh, creaking sound]

stridor (strī´dôr),

n a peculiar, harsh, vibrating sound produced during respiration.
stridor, inspiratory,
n the stridor heard in inspiration through a spasmodically closed glottis.
stridor, laryngeal,
n a stridor resulting from laryngeal stenosis.


a shrill, harsh sound, especially the respiratory sound heard during inspiration in laryngeal obstruction.

laryngeal stridor
that due to laryngeal obstruction. See also roaring.
References in periodicals archive ?
So far, there is a general agreement in the literature that patients with signs and symptoms (including dyspnea, stridor, drooling, respiratory distress, and hypoxia) of severe airway obstruction require an immediate definitive airway, either as an endotracheal tube or a tracheotomy.
There was a history of stridor at birth in two elder male siblings who were evaluated using laryngoscopy.
In our patient the stridor was due to croup but it did not prove to be benign as usual.
Laryngeal ultrasound: a useful method in predicting post-extubation stridor.
By the following day the stridor had resolved, and she was discharged a day later.
The underlying mechanism of postoperative functional stridor is not clear.
Nine hours from the time of injury the patient developed stridor.
1 Signs and symptoms of AFA may be apnea, stridor, wheeze, cough, decreased or abnormal breath sounds depending on the size and location of the foreign body.
Sixteen days later, the curassow presented with acute onset of dyspnea and respiratory stridor.
In more severe cases of croup, there may also be a noisy "crowing" sound as the child takes a breath in, which is known as stridor.
Meanwhile his clinical status got worsened and he was brought to our department with symptoms and findings of anxiety, dyspnea, tachpnea, intercostal and subcostal retractions, wheezing, stridor and arterial oxygen saturation (Sa[O.