Stridor - Causes, Signs, Diagnosis and Management

Introduction:

Stridor is a sign which indicates partial/complete obstruction of the upper respiratory tract leading to compromised airflow through airway passage. It can be observed as a high-pitched sound during both breathing in and breathing out but is more marked while inhaling. 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.

What Is the Prevalence of Stridor?

• Stridor can occur in adults, children as well as infants but is more commonly seen in children as the upper airway is short and narrow compared to adults.

• Adult males are at higher risk than females.

What Causes Stridor?

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

• Choanal Atresia: It is a birth defect involving the nose due to the presence of a membrane between the hard palate and nose. It does not cause any clinical problem 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: It is a fluid-filled mass of tissue formed if the thyroglossal duct fails to close in a normal period. 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 presence of enlarged tonsils/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 is deformed, resulting in the displacement of the supporting structures of the larynx from its normal position resulting in airway obstruction while breathing in 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 that is most commonly seen in children less than 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 stridor on breathing in.

3. Damage to Vocal Cords: Direct trauma to the vocal cords during the insertion of a tube, 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 in the age group of 2-6 years, 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/non-cancerous infections and swellings of the oral cavity may migrate to the neck, causing increased pressure on vital structures of the neck resulting in airway obstruction and stridor like Ludwig's angina.

What Are the Warning Signs of Stridor?

• 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.

1. History:

• The history of any birth defects in newborn children should be noted.

• History of swallowing foreign objects in children and presence of persistent cough.

• The vaccination history of a child, if missed (particularly of influenza vaccine).

2. Physical Examination:

• Clinical evaluation of the presence of any swelling or mass in the neck.

• Assessment of the respiratory rate.

3. X-Ray:

• X-ray of chest and neck for detecting any abnormalities present.

4. Computed Tomographic (CT) Scan and Magnetic Resonance Imaging (MRI):

• It is done to check for any obstruction in the airway due to surrounding structures or any abnormal tissue growth.

5. Bronchoscopy:

• A thin and long instrument with a light on the tip called a bronchoscope 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:

• An apparatus called a spirometer is used to check the volume of the lungs by assessing the amount of air that is breathed in and out.

8. Assessment of Oxygen Saturation in Blood:

• A small sensor instrument placed on the tip of the finger called a pulse oximeter is used to evaluate 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 Can We 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 of 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.

• In cases of deep neck infections or laryngeal edema, IV antibiotics and steroid therapy is started.

• The viral croup should be treated with steroid therapy.

• Surgical management in cases of severe respiratory obstruction.

Conclusion: Stridor is a life-threatening condition if not treated on time. Any signs of airway obstruction noted while breathing should be taken into concern, 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.