⚠️ Chapter 33: Upper Airway Obstruction

Stridor (inspiratory, biphasic, expiratory) · Supraglottic vs glottic vs subglottic · Causes (croup, epiglottitis, FB, anaphylaxis) · Management algorithm · Heliox · Intubation indications · Post-obstructive pulmonary oedema (POPE)

🔍 Core Concepts: Upper Airway Obstruction

📌 Pathophysiology
Resistance ∝ 1/r⁴ → minor oedema increases resistance exponentially. Intrathoracic airway collapses on expiration, extrathoracic collapses on inspiration. Dynamic vs fixed obstruction.
🔊 Stridor types
Inspiratory → supraglottic (croup, epiglottitis). Biphasic → glottic/subglottic (FB, stenosis). Expiratory → intrathoracic (tracheomalacia).
⚠️ Danger signs
Hypoxia is LATE. Impending failure: diminished respiratory efforts, somnolence, decreased/absent stridor, poor air entry. Cardiorespiratory arrest imminent.
💨 Intubation in UAO
NEVER use muscle relaxants (risk of CVCI). Inhalational anaesthesia preferred. Smaller ETT (1/2 size smaller). OR with ENT backup. Avoid agitation.
💊 Medical management
Croup: dexamethasone (0.6 mg/kg), nebulised adrenaline (1:1000, 0.5 mL/kg) for severe. Heliox (80/20) reduces turbulence. Epiglottitis: immediate airway control.
🫁 Post-obstructive pulmonary oedema (POPE)
Occurs after relief of severe UAO (negative pressure). Treat with PEEP, diuretics if haemodynamically stable. Usually resolves in 6-8 hours.

🩺 Stepwise Approach: Upper Airway Obstruction

1
Recognise severity & localise level
Stridor quality (inspiratory → supraglottic; biphasic → glottic/subglottic). Assess work of breathing, mental status, colour. Hypoxia is a late sign.
2
Immediate supportive measures
Allow child to sit upright (tripod). Do NOT agitate. Give blow-by oxygen (don't force mask). Avoid throat examination or IV attempts that cause crying.
3
Medical therapy (croup)
Mild: dexamethasone 0.6 mg/kg PO/IM/IV. Moderate-severe: nebulised adrenaline (1:1000, 0.5 mL/kg, max 5 mL) + steroids. Heliox if available.
4
Indications for intubation
Altered sensorium, rising PaCO2, hypoxia (SpO2 <92% despite high-flow O2), exhaustion, suspected epiglottitis/inhalational injury. Intubate in OR with ENT backup.
5
Intubation technique for UAO
NEVER use muscle relaxants (risk of CVCI). Use inhalational anaesthesia (sevoflurane) or IV ketamine with spontaneous breathing. Use smaller ETT (0.5-1 mm smaller).
6
Post-intubation & POPE
Secure ETT, provide humidification. Monitor for post-obstructive pulmonary oedema (POPE) — pink frothy secretions, hypoxaemia. Treat with PEEP, diuretics if needed.