Why stridor is inspiratory

The obstruction typically worsens in the supine position as gravity pulls the tongue farther back. Tonsillar or adenoidal tissue may be so large that the supraglottic airway becomes obstructed. Characteristically, the stridor is most noticeable during sleep. Retropharyngeal or Peritonsillar Abscess. A retropharyngeal or peritonsillar abscess may cause stridor as edema of the hypopharynx develops.

Although both may present with fever, drooling and dysphagia, the child with a peritonsillar abscess may have difficulty opening the mouth trismus because of spasm of the pterygoid muscles, while the child with a retropharyngeal abscess often keeps the neck hyperextended.

Laryngomalacia is the most common cause of chronic stridor in children younger than two years. It has a male-to-female ratio of approximately The airway is partially obstructed during inspiration by the prolapse of the flaccid epiglottis, arytenoids and aryepiglottic folds. The inspiratory stridor is usually worse when the child is in a supine position, when crying or agitated, or when an upper respiratory tract infection occurs.

Laryngeal Web, Cyst or Laryngocele. A laryngeal web results from a failure of the embryonic airway to recanalize. A laryngeal cyst usually contains mucus from minor salivary glands.

A laryngocele arises as a dilatation of the saccule of the laryngeal ventricle. A laryngeal web, cyst or laryngocele may present with stridor, usually at birth or soon after. Laryngotracheobronchitis Viral Croup. The most common cause of acute stridor in childhood is laryngotracheobronchitis, or viral croup. The condition is caused most commonly by parainfluenza virus, but it can also be caused by influenza virus types A or B, respiratory syncytial virus and rhinoviruses.

The male-to-female ratio is approximately A low-grade fever, barking cough, inspiratory stridor and hoarseness then develop. Symptoms are characteristically worse at night and are aggravated by agitation and crying. Acute Spasmodic Laryngitis Spasmodic Croup. Spasmodic croup may mimic laryngotracheobronchitis, except that it is usually not preceded by an upper respiratory tract infection, and it often occurs with a sudden onset at night.

Allergy, psychologic factors and gastroesophageal reflux may trigger spasmodic croup. Spasmodic croup may be recurrent. In children, epiglottitis is almost always caused by Haemophilus influenzae type b.

The disease is characterized by an abrupt onset of high fever, toxicity, agitation, stridor, dyspnea, muffled voice, dysphagia and drooling. The older child may prefer to sit leaning forward with the mouth open and the tongue somewhat protruding.

There is no spontaneous cough. An edematous, cherry red epiglottis, visualized in a controlled environment, is the hallmark of epiglottitis. Vocal Cord Paralysis. Unilateral vocal cord paralysis occurs more often on the left side because of the longer course of the recurrent laryngeal nerve, which makes it more vulnerable to injury. Unilateral dysfunction may result from birth trauma, trauma during thoracic surgery or compression by mediastinal masses of cardiac, pulmonary, esophageal, thyroid or lymphoid origin.

Bilateral vocal cord paralysis is more commonly associated with central nervous system problems including perinatal asphyxia, cerebral hemorrhage, hydrocephalus, bulbar injury and Arnold-Chiari malformation. In vocal cord paralysis, the stridor is typically biphasic. In unilateral vocal cord paralysis, the infant's cry is weak and feeble; however, there is usually no respiratory distress.

In bilateral vocal cord paralysis, the voice is usually of good quality, but there is marked respiratory distress. Laryngotracheal Stenosis. Laryngotracheal stenosis is a congenital or acquired narrowing of the airway representing a continuum of disease that may affect the glottis, subglottis and trachea. Other causes include blunt trauma to the neck, high tracheotomy, cricothyrotomy, external compression of the airway and gastroesophageal reflux.

Intubation may result in vocal cord paralysis, laryngotracheal stenosis, subglottic edema and laryngospasm. Any of the above, alone or in combination, may lead to airway obstruction and stridor. Foreign Body.

Foreign body aspiration is a common cause of acute stridor. The peak incidence is between one and two years of age. The foreign body is usually food. A history of aspiration or choking can be obtained in 90 percent of cases. The most common symptoms of laryngotracheal foreign bodies are cough, stridor and dyspnea, whereas those of bronchial foreign bodies are cough, decreased breath sounds, wheezing and dysphagia. Stridor may occur because of direct compression of the trachea by large objects lodged in the postcricoid region, paraesophageal inflammation, abscess formation or direct extension of the inflammatory process into the trachea by ulceration and fistula formation.

Cystic Hygroma. A cystic hygroma is a collection of lymphatic sacs that contain clear, colorless lymph. The lesion is congenital and probably represents a cluster of lymph channels that failed to connect into the normal lymphatic pathway.

It commonly occurs in the neck area Figure 2. The tumor, as it grows, may cause tracheal compression and stridor. Subglottic Hemangioma.

A subglottic hemangioma occurs more commonly in girls, with a female-to-male ratio of No color change or, at most, a slight bluish discoloration is evident. It is frequently associated with hemangiomas elsewhere on the body. The stridor is biphasic and exaggerated by crying or straining as the lesion tends to become engorged. Laryngeal Papilloma. This is the most common laryngeal neoplasm in children and usually results from vertical transmission of human papillomavirus at birth.

Usually multiple, papillomas most commonly occur in the vocal cords and ventricular bands but can involve any part of the larynx. They are most common in children between two and four years of age. The usual presenting symptom is hoarseness, but some patients have stridor and other signs of laryngeal obstruction. Angioneurotic Edema. Angioneurotic edema may result in acute swelling of the upper airway with resultant stridor and dyspnea.

Swelling of the face, tongue or pharynx may also be present. Laryngospasm Hypocalcemic Tetany. Hypocalcemia may rarely cause laryngospasm and stridor. Psychogenic Stridor. Stridor may be caused by emotional stress or it may be a manifestation of a conversion disorder. Vocal cord malfunction associated with emotional stress may result in inspiratory or expiratory stridor. Characteristically, the onset of stridor is sudden but without the expected amount of distress. The neck is often held in a flexed position rather than in an extended position.

Tracheomalacia is characterized by abnormal tracheal collapse secondary to inadequate cartilaginous and myoelastic elements supporting the trachea. Tracheal narrowing occurs with expiration and causes stridor.

The stridor is usually aggravated by respiratory tract infections and agitation. Bacterial Tracheitis. Bacterial tracheitis is usually caused by Staphylococcus aureus , although it can also be caused by H. Most patients are younger than three years of age.

Bacterial tracheitis usually follows an upper respiratory tract infection. The patient then becomes seriously ill with high fever, toxicity and respiratory distress. External Compression. Tracheal compression may result from vascular anomalies such as double aortic arch, right aortic arch with left ligamentum arteriosum, anomalous innominate artery, anomalous left common carotid artery, anomalous left pulmonary artery or aberrant subclavian artery.

The child may prefer to keep the neck hyperextended. The stridor resulting from tracheal compression is often aggravated by feeding. A thorough history Table 2 and physical examination Table 3 are important in the evaluation of children with stridor. Figure 3 presents an algorithm helpful in evaluating stridor in children. Recent intubation or neck surgery should be clinically obvious. If chronic, the age at onset eg, since birth, since infancy, only in adulthood and duration are determined, as well as whether symptoms are continuous or intermittent.

For intermittent symptoms, provoking or exacerbating factors eg, position, allergen exposure, cold, anxiety, feeding, crying are sought. Important associated symptoms in all cases include cough, pain, drooling, respiratory distress, cyanosis, and difficulty feeding. Review of systems should seek symptoms suggesting causative disorders, including heartburn or other reflux symptoms laryngospasm ; night sweats, weight loss, and fatigue cancer ; and voice change, trouble swallowing, and recurrent aspiration neurologic disorders.

Past medical history in children should cover perinatal history, particularly regarding need for endotracheal intubation, presence of known congenital anomalies, and vaccination history particularly HiB. In adults, history of prior endotracheal intubation, tracheotomy, recurrent respiratory infections, and tobacco and alcohol use should be elicited.

The first step is to determine the presence and degree of respiratory distress by evaluating vital signs including pulse oximetry and doing a quick examination. Children with epiglottitis may sit upright with arms braced on the legs or examination table, lean forward, and hyperextend the neck with the jaw thrust forward and mouth open in an effort to enhance air exchange tripod position. Moderate distress is indicated by tachypnea, use of accessory muscles of respiration, and intercostal retractions.

If distress is severe, further examination is deferred until equipment and personnel are arranged for emergency management of the airway. Oropharyngeal examination of a patient particularly a child with epiglottitis may provoke anxiety, leading to functional obstruction and loss of the airway.

Thus, if epiglottitis is suspected, a tongue depressor or other instrument should not be placed in the mouth. When suspicion is low and patients are in no distress, they may undergo imaging; others should be sent to the operating room for direct laryngoscopy, which should be done by an otolaryngologist with the patient under anesthesia.

The neck is palpated for masses and tracheal deviation. Careful auscultation of the nose, oropharynx, neck, and chest may help discern the location of the stridor. Infants should be examined with special attention to craniofacial morphology looking for signs of congenital malformations , patency of the nares, and cutaneous abnormalities.

The distinction between acute and chronic stridor is important. Other clinical findings are also often helpful see table Some Causes of Stridor Some Causes of Stridor Stridor is a high-pitched, predominantly inspiratory sound. Acute manifestations are more likely to reflect an immediately life-threatening disorder. With these disorders, fever indicates infection. Fever plus barking cough suggests croup or, very rarely, tracheitis.

Patients with croup typically have more prominent symptoms of upper respiratory infection and less of a toxic appearance. Fever without cough, particularly if accompanied by toxic appearance, sore throat, difficulty swallowing, or respiratory distress, suggests epiglottitis and, in young children, the less common retropharyngeal abscess. Drooling and the tripod position are suggestive of epiglottitis, whereas retropharyngeal abscess may manifest with neck stiffness and inability to extend the neck.

Patients without fever or symptoms of upper respiratory infection may have an acute allergic reaction or aspirated foreign body. Acute allergic reaction severe enough to cause stridor usually has other manifestations of airway edema eg, oral or facial edema, wheezing or anaphylaxis itching, urticaria.

Foreign body obstruction of the upper airway that causes stridor is always acute but may be occult in toddlers older children and adults can communicate the event unless there is near-complete airway obstruction, which will manifest as such, not as stridor. Cough is often present with foreign body but rare with allergic reaction.

Chronic stridor that begins early in childhood and without a clear inciting factor suggests a congenital anomaly or an upper airway tumor. In adults, heavy smoking and alcohol use should raise suspicion of laryngeal cancer. Vocal cord paralysis usually has a clear precipitant, such as surgery or intubation, or is associated with other neurologic findings, such as muscle weakness. Health Conditions Discover Plan Connect. Types of stridor. What causes stridor?

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