Summary of "Stridor in children (causes, inspiratory and expiratory stridor, pathophysiology)"

Summary of “Stridor in children (causes, inspiratory and expiratory stridor, pathophysiology)”

This video provides a detailed overview of stridor in children, focusing on its causes, types (inspiratory and expiratory), pathophysiology, and important clinical considerations. Stridor is described as a high-pitched, monophonic sound caused by partial airway obstruction leading to turbulent airflow. It is usually loud enough to be heard without a stethoscope.

Main Ideas and Concepts

Definition of Stridor

High-pitched, monophonic sound.
Caused by partial obstruction of large airways.
Loud and audible without a stethoscope.
Most common in children due to various causes.

Types of Stridor

Inspiratory stridor: Caused by obstruction in the extra-thoracic airway (from nose to larynx and trachea).
Expiratory stridor: Caused by obstruction in the intra-thoracic airway (distal trachea, bronchi).
Pathophysiology depends on airflow dynamics during inspiration and expiration.

Anatomical Division of Causes

Extra-thoracic region: Nose, pharynx, larynx, trachea.
Intra-thoracic region: Distal trachea, bronchi.

Common Causes of Stridor

Acute Causes

Croup: Most common acute cause; viral infection (parainfluenza virus), characterized by barking cough, inspiratory stridor, hoarseness.
Anaphylaxis: Life-threatening allergic reaction causing airway edema and obstruction.
Epiglottitis: Medical emergency caused by Haemophilus influenzae type B; presents with fever, drooling, muffled voice, and airway obstruction.
Bacterial tracheitis: Infection causing subglottic edema and secretions; often due to Staphylococcus aureus.
Foreign body aspiration: Can cause obstruction anywhere in the airway leading to inspiratory, expiratory, or mixed stridor.

Chronic or Congenital Causes

Laryngomalacia: Most common congenital cause; flaccid laryngeal structures collapse during inspiration causing inspiratory stridor, worse when supine or agitated.
Laryngeal web: Fibrous tissue between vocal cords causing partial obstruction.
Vocal cord paralysis: Can be unilateral or bilateral.
Tracheomalacia: Soft trachea with collapse during expiration causing expiratory stridor.
Tracheoesophageal fistula: Abnormal connection causing airway problems.

Other Causes of Extra-thoracic Obstruction

Enlarged adenoids and tonsils (due to infections or malignancy).
Macroglossia (enlarged tongue) from allergies, congenital causes, or infections like Ludwig’s angina.

Anatomical and Clinical Details

Explanation of airway anatomy including larynx, epiglottis, vocal cords, trachea, and esophagus.
Description of how airflow and pressure changes during inspiration and expiration affect airway collapse and stridor type.
Visual and clinical signs of epiglottitis and croup.
Importance of recognizing emergency conditions like anaphylaxis and epiglottitis for timely treatment.

Methodology / Key Points for Clinical Understanding

Identify stridor type by phase of respiration:
- Inspiratory → Extra-thoracic obstruction.
- Expiratory → Intra-thoracic obstruction.
Consider the anatomical site for differential diagnosis:
- Extra-thoracic: Nose to trachea.
- Intra-thoracic: Distal trachea and bronchi.
Recognize common causes based on age and presentation:
- Acute inspiratory stridor in children → Croup, epiglottitis, anaphylaxis.
- Chronic inspiratory stridor → Laryngomalacia.
- Expiratory stridor → Tracheomalacia.
Emergency management:
- Anaphylaxis → Immediate adrenaline (epinephrine).
- Epiglottitis → Secure airway, possible prophylactic intubation.
Look for associated signs:
- Barking cough and hoarseness → Croup.
- Drooling, muffled voice, sitting forward → Epiglottitis.
- History of allergen exposure → Anaphylaxis.
- Sudden onset with choking → Foreign body aspiration.

Summary

Stridor is a loud, high-pitched sound caused by partial airway obstruction.
Inspiratory stridor is due to extra-thoracic obstruction; expiratory stridor is due to intra-thoracic obstruction.
The most common acute cause of stridor in children is croup.
The most common congenital cause of stridor is laryngomalacia.
Life-threatening causes like anaphylaxis and epiglottitis require urgent recognition and treatment.
Understanding airway anatomy and airflow dynamics is crucial for diagnosis and management.