Stridor - Causes, Signs, Diagnosis and Management

What Is Stridor?

A stridor is a sign that indicates partial or complete obstruction of the upper respiratory tract, leading to compromised airflow through airway passage. It can be observed as a high-pitched sound when breathing in and breathing out, but it is more marked when breathing in. A sign of stridor is a marked medical emergency that seeks immediate medical attention to evaluate the cause behind the obstruction of the upper respiratory tract, which may involve the nose, voice box, mouth, windpipe, or sinuses.

How Common Is Stridor?

• Stridors can occur in adults, children, and infants, but they are more commonly seen in children because their upper airways are shorter and narrower than those of adults.

• Adult males are at higher risk than females.

What Are the Types of Stridor?

The types of stridor are as follows:

• Inspiratory Stridor: It is associated with upper airway obstruction and is heard during breath-in.

• Expiratory Stridor: It is associated with lower airway obstruction and is heard during exhalation.

• Biphasic Stridor: It is present during breathing in and out.

• Congenital Stridor: It is present from birth and is caused by structural abnormalities.

• Acquired Stridor: It develops later in life and is caused by infections, trauma, and tumors that affect the airway.

What Causes Stridor?

1. Birth Defects: Various birth defects, abnormal growth, and development in infants can result in stridors like:

• Choanal Atresia: It is a birth defect involving the nose due to the presence of a membrane between the hard palate and the nose. It does not cause any clinical problems if only one side of the nose is affected, but it is life-threatening if it involves both sides, as it causes respiratory obstruction in newborns.

• Thyroglossal Duct Cyst: A fluid-filled tissue mass forms if the thyroglossal duct fails to close normally. It is present in the midline of the neck and moves with tongue movement. If left untreated, the mass can enlarge and cause airway obstruction, leading to stridor.

• Hypertrophic Tonsils: The enlarged tonsils or adenoid tissues can obstruct airway passage, resulting in stridor.

• Laryngomalacia: It is a condition in which the formation of supporting structures of the larynx (voice box) is either very late or deformed, resulting in its displacement from its normal position and airway obstruction while breathing, causing stridor. It is a chronic form of stridor and is mostly seen in children less than two years of age.

2. Viral Croup: It is a parainfluenza viral infection most commonly seen in children under six years of age. Hemophilus influenza virus types A and B can also be responsible sometimes. It causes upper respiratory tract infections with fever, cough, and difficulty breathing in.

3. Damage to Vocal Cords: Direct trauma to the vocal cords during the insertion of a tube may damage them, while surgery can cause vocal cord paralysis. It may involve one side or both and cause marked respiratory distress or stridor.

4. Swallowing of the Foreign Object: Swallowing of small objects or food particles gets stuck into the upper airway tract, leading to choking and acute stridor. The object should be immediately dislodged to clear the airway obstruction by manual pressure on the abdomen between the navel and rib cage.

5. Swelling of the Epiglottis: For children aged between two and six years, the Haemophilus influenzae type B virus can cause inflammation of the epiglottis and cause stridor.

6. Swelling of the Trachea: Swelling of the trachea (windpipe) caused by a bacterial infection (Staphylococcus aureus) results in severe respiratory infection and stridor.

7. Deep Neck Infections: Cancerous or non-cancerous infections and swellings of the oral cavity may migrate to the neck, causing increased pressure on vital neck structures, resulting in airway obstruction and stridor like Ludwig's angina.

What Are the Warning Signs of Stridor?

The warning signs of stridor are described below:

• Choking sensation or shortness of breath.

• Unconsciousness.

• Drooling is mostly observed in the inflamed epiglottis and after swallowing a foreign object.

• Change in voice.

• Excessive coughing.

• Bluish discoloration of the skin.

• Chest pain.

How Can We Diagnose Stridor?

Early diagnosis and management of stridor are very crucial. The diagnosis of stridor is described below:

1. History: The healthcare provider may take a history of any birth defects in newborn children, swallowing foreign objects in children, the presence of persistent cough, and the vaccination history of a child, if missed (particularly of influenza vaccine).

2. Physical Examination: The doctor may clinically evaluate the presence of any swelling or mass in the neck and assess the respiratory rate.

3. X-ray: X-ray of the chest and neck to detect any abnormalities present.

4. Computed Tomographic (CT) Scan and Magnetic Resonance Imaging (MRI): These are done to check for obstruction in the airway due to surrounding structures or abnormal tissue growth.

5. Bronchoscopy: A bronchoscope is a thin, long instrument with a light on the tip that is used to check the throat, larynx, trachea, and bronchus.

6. Laryngoscopy: An apparatus is used to check any obstruction in the throat and larynx.

7. Spirometry: A spirometer is an apparatus used to check the volume of the lungs by assessing the amount of air breathed in and out.

8. Assessment of Oxygen Saturation in Blood: A pulse oximeter is a small sensor instrument placed on the tip of the finger. It evaluates the oxygen content of the blood.

9. Sputum Test: A sample of sputum is taken from a cough and sent to the laboratory to identify the type of respiratory infection.

How to Manage Stridor?

For effective management of stridor, it is very crucial to be aware of the appropriate cause of stridor.

• Dislodgement of an object, if stridor, is due to swallowing a foreign body.

• Immediate artificial ventilation and oxygen therapy should be given if required.

• In cases of infections, intravenous antibiotic therapy should be started.

• If stridor is due to the presence of Ludwig's angina, pressure on vital structures should be relieved immediately by incision and drainage.

• IV antibiotics and steroid therapy are started in cases of deep neck infections or laryngeal edema.

• The viral croup should be treated with steroid therapy.

• Surgical management in cases of severe respiratory obstruction.

How to Reduce the Risk of Stridor?

The following methods can reduce the risk of stridor:

• Avoid smoking.

• Maintain good hygiene to prevent infections.

• Manage allergies.

• Stay hydrated.

• Prompt treatment of respiratory infections, such as colds and flu.

• Avoid exposure to irritants, such as pollutants and chemicals.

Conclusion:

Stridor is a life-threatening condition if not treated on time. The person may experience chest pain, shortness of breath, a change in voice, bluish discoloration of the skin, and a choking sensation. Any signs of airway obstruction noted while breathing should be considered, and an immediate appointment should be made with an ENT doctor. If left untreated, stridor can lead to complete airway obstruction and even death due to respiratory failure, so early diagnosis and management should be made.