What are the causes of supraglottic edema?

Causes of Supraglottic Edema

Supraglottic edema results from a combination of infectious, traumatic, iatrogenic, and systemic causes, with the most critical being infectious epiglottitis, airway instrumentation trauma, and anaphylaxis—all of which can rapidly progress to life-threatening airway obstruction.

Infectious Causes

Bacterial Infections

• Epiglottitis (supraglottitis) is the most common infectious cause, resulting in inflammation and edema of the epiglottis and neighboring supraglottic structures 1
• While historically predominant in children aged 2-6 years, the incidence in adults is now increasing following widespread Haemophilus influenzae B (HiB) vaccination 1
• Retropharyngeal cellulitis and retropharyngeal abscess can extend to cause supraglottic edema 2
• Ludwig's angina (severe submandibular space infection) can cause significant supraglottic edema requiring emergency airway management 3

Clinical Presentation of Infectious Causes

• Fever, sore throat, muffled voice, drooling, tripod positioning, and stridor indicate impending airway obstruction 1
• These infections represent serious pediatric and adult emergencies requiring high clinical suspicion and rapid intervention 2

Traumatic and Iatrogenic Causes

Surgical Trauma

• Head and neck surgery is a major cause: thyroid surgery, laryngoscopy, panendoscopy, maxillofacial procedures, cervical spine surgery, and carotid procedures can all cause direct airway compromise through edema, haematoma, altered lymphatic drainage, vocal cord paralysis, and tracheomalacia 4

Airway Instrumentation Trauma

• Laryngoscopy and intubation can cause periglottic trauma leading to supraglottic edema 4
• Transoesophageal echocardiography probes and nasogastric tubes can cause periglottic trauma 4
• Inappropriately large endotracheal tube sizes and excessive cuff pressure contribute to edema 4
• Incorrectly positioned tracheal tubes (e.g., cuff inflated within the larynx) cause direct supraglottic injury 4
• Movement of oversized or poorly positioned tracheal tubes on the posterior glottis and arytenoid cartilages leads to edema and compromised airflow 4
• Supraglottic swelling and edema can cause posterior displacement of the epiglottis, typically resulting in inspiratory obstruction 4

Positional and Duration Factors

• Prone positioning or prolonged Trendelenburg positions during surgery contribute to airway edema 4
• Duration of surgery correlates with increased edema risk 4

Systemic and Fluid-Related Causes

Fluid Overload

• Excessive intravenous fluid administration during prolonged procedures contributes significantly to airway edema 4

Anaphylaxis

• Allergic reactions can cause rapid, severe supraglottic edema (angioedema) requiring immediate recognition and treatment 4
• Supraglottic allergic edema (angioedema) represents one of the six major types of acute laryngeal obstruction 5

Mechanical and Pressure-Related Causes

Negative Pressure Effects

• Forceful inspiratory effort against obstruction generates significant negative intrathoracic pressure, which can worsen edema 4

Lymphatic Drainage Impairment

• Surgical disruption of lymphatic drainage pathways contributes to persistent supraglottic edema 4

Clinical Pitfalls and Risk Assessment

High-Risk Scenarios Requiring Vigilance

• Problems from airway injury often do not become apparent until after tracheal extubation, making post-extubation monitoring critical 4
• The ASA closed-claims analysis showed 33% of airway injuries occurred at the larynx, with most (85%) associated with short-term tracheal intubation and 80% following routine (not difficult) intubation 4

Key Risk Factors to Identify

• Traumatic intubation, prolonged intubation, repeated intubations, or direct laryngeal trauma all increase risk 6
• A negative leak test indicates increased risk of laryngeal edema and should prompt preventive therapy 6

Management Implications

Prevention Strategy

• Begin corticosteroid therapy (dexamethasone) at least 12-24 hours before planned extubation in high-risk patients 6
• The American Society of Anesthesiologists recommends intravenous dexamethasone with repeated doses before and after extubation to decrease stridor and reintubation risk 6

Emergency Recognition

• Position patients with airway compromise upright and administer high-flow humidified oxygen 6
• Consider epinephrine nebulization for post-extubation stridor, which has quick onset but transient effect 6
• Have equipment for reintubation readily available, including airway exchange catheters in high-risk cases 6