Stridor

Alexandra Duke and Tahany Maurice-Habashy

Stridor is a common type of wheezing (Chapter 8.9). It is characterized by a harsh, raspy, medium-pitched sound produced as air flows through a partially blocked airway. It is usually seen in early childhood.

Approach

Stridor can be inspiratory, indicating obstruction at or above the larynx; or expiratory, indicating obstruction below the larynx. Biphasic stridor is an obstruction in the trachea; it is heard with inspiration and expiration. When hoarseness or aphonia accompanies stridor, the vocal cords are involved (Table 8.4) (1–5).

History

A. Characteristics of stridor. When confronted with stridor, check the age of the patient and the duration of the symptoms.

1. A child aged less than 6 months with stridor of a few weeks to months has a congenital cause of stridor.

2. Patients aged more than 6 months with stridor lasting hours to days usually have an acquired cause of stridor, most commonly viral croup, epiglottitis, or aspiration of a foreign body.

 3. A typical history is a child aged less than 6 years with a 2- to 3-day history of upper respiratory infection (URI) and gradually worsening cough, especially at night. A barking cough with the inspiratory stridor heralds the diagnosis of croup, which accounts for 90% of all cases of stridor. This condition will classically improve with moist air (1,3).

 4. A history of choking, coughing, or gagging points to aspiration or ingestion of a foreign body.

5. In older children and adults, a concomitant sore throat and fever may indicate acute supraglottitis, which constitutes an emergency.

B. Other information

1. Whether stridor is acute, recurrent, or chronic.

 2. Personal or family history of atopy, would suggest spasmodic croup, which presents with stridor at night, not necessarily associated with a URI.

Physical examination

A. Focused physical examination (PE)

1. The PE should include vital signs, notably temperature and respiratory rate, and pulse, with emphasis on general appearance and examination of the head and neck, including ears, nose, and throat.

2. Signs of respiratory distress may be present, including dyspnea, tachypnea, chest retractions, nasal flaring, and stridor. If cyanosis is present, this is an ominous sign (2,4) (Chapter 8.2).

B. Additional physical examination may reveal:

1. A toxic-appearing child with high fever, drooling, severe respiratory distress, and preference for a sitting and forward-leaning position (1,4)

2. Varying degrees of anxiety, which will increase during examination, cause a worsening of stridor (1,4)

Testing

A. The best test is a lateral neck x-ray study to assist with a diagnosis that is mostly made on clinical grounds. Films of the larynx and trachea in anteroposterior and lateral neck views may show narrowing of the trachea or extrinsic pressure on the tracheobronchial airway. Acutely, lateral neck radiographs showing the classic swollen glottis described by some as a thumbprint, assist with the diagnosis of acute supraglottitis and eminent respiratory collapse. Chest x-ray studies are of little value. Films showing hyperinflation or bronchial thickening may help to make a diagnosis of asthma rather than stridor. Additionally, foreign body aspiration or mass will be elucidated in x-ray studies (2).

B. Tomograms or computed tomography (CT) of the neck may provide additional information, especially in chronic stridor (2).

C. Blood tests (e.g., complete blood count) can be useful in the acutely ill patient, especially if viral or bacterial infection is suspected.

D. With suspicion that the stridor is a result of a laryngomalacia or laryngeal lesions such as papilloma, direct laryngoscopy is the test of choice for accurate diagnosis. Direct observation via fiberoptic bronchoscope positioned in the pharynx would provide diagnostic views of the larynx (2,4).

Diagnostic assessment

In making the diagnosis of stridor, two key elements exist: acute onset in a toxic-appearing patient, versus chronic stridor in a relatively stable patient.

A. Acute stridor

 1. The most likely cause of acute stridor in the febrile child with the additional features of barking cough and antecedent coryza is laryngotracheobronchitis or croup. Acute stridor is a non–life-threatening condition accounting for 90% of stridor cases. Classically, it improves with exposure to moist air. It has a viral cause, usually from one of the following: respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza virus, and influenza virus. Generally, this diagnosis is made on clinical grounds (1). The child is less ill and, although often febrile, not toxic appearing. The entire illness usually abates in 5 days. Hospitalization, unlike with epiglottitis, is rarely needed (2).

2. In the toxic patient with fever, respiratory distress, sore throat, or drooling, especially in the younger age group, consider epiglottitis—a medical emergency. As use of the Haemophilus influenzae vaccine has increased in recent years, acute epiglottis is becoming increasingly rare. H. influenzae is the most common bacterial cause of stridor, although streptococcus, staphylococcus and viral agents are also possible causes.

 3. The patient with a history of suspected foreign body aspiration will have similar symptoms without fever. Foreign body aspiration is common in the 1- to 2-year age groups, although it does occur in adults. It can be a cause of chronic stridor (3).

 4. Additionally, an acute allergic reaction can cause stridor. The history should herald a possible offending agent and, although respiratory collapse may be eminent, the patient will not be toxic, as no infectious agent is involved.

 5. Trauma can also cause laryngeal damage; however, the history will assist with this diagnosis.

 B. Chronic stridor. For the most part, these causes of stridor occur in early childhood. With the exception of laryngeal papillomas, tumors, and subglottic stenosis after instrumentation as in intubation (there is a congenital form also), foreign body aspiration with partial obstruction and hysterical stridor can occur at any age. Laryngomalacia and laryngeal lesions are caused by webs, hemangiomas, and cysts; they are usually identified early in life (1–3).

References

1. Pryor MP. Noisy breathing in children. Postgrad Med 1997;101:103–112.

2. Behrman RE, Kliegman RM, Arvin AM. Nelson textbook of pediatrics. Philadelphia: WB Saunders, 1996:241, 1173, 1198, 1238.

3. Behrman RE, Vaughan VC. Nelson textbook of pediatrics. Philadelphia: WB Saunders, 1983:1031–1032, 1076–1077.

4. Tintinalli JE, Ruiz E, Krome RL. Emergency medicine: a comprehensive study guide. New York: McGraw-Hill, 1996:247–251.

5. Campbell AGM, MacIntosh N. Textbook of pediatrics. London: Pearson Ltd., 1998:
508–513, 563.

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Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

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