Airway Obstruction: Etiology and Pathogenesis

Introduction

• Airway obstruction can occur at various anatomical sites such as the nasopharynx, oropharynx, hypopharynx, oral cavity, larynx, trachea, bronchial tree, and mediastinum.

Etiology

• Acute Obstruction:

  • Life-threatening causes include anaphylaxis, foreign body in the larynx or trachea, juvenile onset respiratory papillomatosis (HPV types 6 and 11), and laryngeal cancers.

• Sub-acute Obstruction:

  • Often caused by adenotonsillar hypertrophy.

• Chronic Obstruction:

  • Typically has a congenital or acquired basis.

• Congenital Causes:

  • Naso-, oro-, hypo-pharynx, and oral cavity abnormalities include choanal atresia and stenosis, mid nasal stenosis, and skull base anomalies (e.g., Down’s syndrome).
  • Larynx and tracheobronchial conditions: laryngomalacia, tracheomalacia, cysts/webs, vascular rings.

• Acquired Causes:

  • Infectious/inflammatory causes like acute and chronic laryngitis, epiglottitis, croup, and bacterial tracheitis.
  • Trauma from blunt/penetrating injuries or iatrogenic causes (e.g., intubation).
  • Neoplastic causes include squamous cell carcinoma, laryngeal papillomatosis, and hemangiomas.
  • Allergic causes such as anaphylaxis and angioedema.
  • Other developmental abnormalities can also contribute.

Pathogenesis

• Intra-luminal Obstruction:

  • Obstruction within the airway caused by foreign bodies or tumors.

• Luminal Obstruction:

  • Thickened or narrowed airway due to inflammation, infection, or neoplastic growth.

• Extra-luminal Obstruction:

  • External compression from masses, lymphadenopathy, or other structures.

Mechanisms of Obstruction

• Hoarseness:

  • Resulting from inflammatory conditions (acute and chronic laryngitis), neoplasia (papillomatosis, cancers), neurological disorders (CVA, multiple sclerosis), iatrogenic effects, or systemic diseases (hypothyroidism, rheumatoid arthritis).

• Stridor:

  • A high-pitched sound indicating airway obstruction:
    • Inspiratory stridor suggests laryngeal obstruction.
    • Expiratory stridor indicates distal trachea and mainstem bronchi obstruction.
    • Biphasic stridor occurs with glottis, subglottis, and upper trachea obstruction.

• Stertor:

  • Noisy breathing from tissue vibration above the larynx, often due to adenotonsillar hypertrophy.

Effects of Airway Obstruction

• Acute Effects:

  • Life-threatening situations necessitating urgent medical intervention.

• Chronic Effects:

  • Long-term complications include persistent breathing difficulties, chronic infections, and alterations in vocal quality.

• Age-specific Effects:

  • Neonates: At risk for congenital cysts, laryngomalacia, and vocal cord paralysis.
  • Children: Prone to conditions like croup, epiglottitis, acute laryngitis, and respiratory papillomatosis.
  • Adults: Common causes are laryngeal cancer, trauma, laryngeal/tracheal stenosis, and anaphylaxis.

This quiz explores the etiology and pathogenesis of airway obstruction, covering various critical conditions that can occur in anatomical regions such as the nasopharynx, larynx, and bronchial tree. Understand the life-threatening nature of acute obstructions and their causes, including anaphylaxis and foreign bodies. Test your knowledge on this essential medical topic.