About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Stridor is upper airway obstruction until proven otherwise; wheeze is usually intrathoracic lower airway obstruction
- Do not agitate a child with suspected epiglottitis or critical airway obstruction — keep them upright, with caregiver, and call expert airway support
- Must-not-miss causes: anaphylaxis/angio-oedema, epiglottitis, foreign body, bacterial tracheitis, deep neck space infection, airway trauma/burns
- Croup is common and usually viral: barking cough, hoarseness, inspiratory stridor; treat with dexamethasone and nebulised epinephrine if moderate-severe
- Drooling, toxic appearance, tripod position, muffled voice, or inability to swallow is epiglottitis/deep neck infection until proven otherwise
Approach to the Presentation
Stridor indicates turbulent airflow through a narrowed upper airway. The assessment is deliberately minimal when the airway is precarious: observe work of breathing, position, drooling, voice, colour, mental status, and oxygenation without forcing the patient to lie flat or open their mouth. In children, croup is the common benign-to-moderate diagnosis, but epiglottitis, bacterial tracheitis, foreign body, and retropharyngeal abscess are dangerous alternatives. In adults, consider anaphylaxis, angio-oedema, tumour, vocal cord dysfunction, inhalational injury, post-extubation oedema, and deep neck infection. The MCCQE1 rewards recognising when the next best step is airway preparation rather than diagnostic imaging.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Anaphylaxis / Angio-oedema | must-not-miss | Acute stridor or hoarseness with lip/tongue swelling, urticaria, wheeze, hypotension, GI symptoms after allergen/drug/food/sting. ACE inhibitor can cause bradykinin angio-oedema without urticaria | Clinical diagnosis; immediate IM epinephrine for anaphylaxis. Airway evaluation by expert if progressive swelling |
| Epiglottitis / Supraglottitis | must-not-miss | High fever, toxic appearance, severe sore throat, drooling, dysphagia, muffled voice, tripod posture; cough often absent. Occurs in unimmunised children and adults | Clinical airway diagnosis; fibreoptic laryngoscopy in controlled setting. Do not agitate or force throat exam in unstable child |
| Foreign Body Aspiration | must-not-miss | Sudden choking, coughing, unilateral wheeze or stridor, abrupt onset during eating/play, child or older adult with dysphagia | Clinical; inspiratory/expiratory films may show air trapping. Rigid bronchoscopy if suspected |
| Bacterial Tracheitis | must-not-miss | Toxic child, high fever, stridor, thick secretions, poor response to nebulised epinephrine; can follow viral croup | Airway endoscopy/culture after airway secured; CXR may show irregular tracheal narrowing |
| Inhalational Injury / Airway Burn | must-not-miss | Smoke exposure, facial burns, singed nasal hairs, soot in mouth/sputum, hoarseness, carbon monoxide risk; oedema can progress rapidly | Clinical; carboxyhaemoglobin level; early airway visualisation/intubation if concerning |
| Croup (Laryngotracheobronchitis) | common | Age 6 months-3 years typical, viral prodrome, barking cough, hoarse voice, inspiratory stridor worse at night; usually non-toxic | Clinical diagnosis; imaging not required in typical cases |
| Retropharyngeal / Peritonsillar Abscess | less common | Fever, sore throat, neck stiffness, drooling, muffled voice. Retropharyngeal: limited neck extension, young child. Peritonsillar: uvular deviation, trismus | CT neck with contrast if stable; ENT assessment and drainage when indicated |
| Post-Extubation Laryngeal Oedema | less common | Stridor after recent intubation, especially prolonged intubation, traumatic tube, large tube, female sex, airway swelling | Clinical; cuff leak test may predict risk before extubation in ICU |
| Vocal Cord Dysfunction / Inducible Laryngeal Obstruction | less common | Intermittent inspiratory noise, throat tightness, exercise/stress trigger, normal oxygenation, poor bronchodilator response | Laryngoscopy during symptoms; flow-volume loop may show inspiratory flattening |
| Airway Tumour / Tracheal Stenosis | rare | Progressive stridor, voice change, haemoptysis, weight loss, smoking history, prior intubation/tracheostomy, fixed symptoms | CT neck/chest and bronchoscopy/laryngoscopy |
Red Flags & Key History
Symptoms
Drooling, dysphagia, muffled voice, tripod posture — epiglottitis or deep neck infection
Rapid swelling of lips/tongue/face or urticaria/hypotension — anaphylaxis/angio-oedema
Sudden choking episode — foreign body until proven otherwise
Smoke exposure, facial burns, hoarseness, soot — inhalational injury
Barking cough, hoarse voice, viral prodrome, worse at night — croup pattern
Progressive voice change, haemoptysis, weight loss — tumour or fixed airway lesion
Signs
Cyanosis, altered mental status, fatigue, quieting stridor — impending airway failure
Toxic appearance with high fever — bacterial tracheitis, epiglottitis, abscess
Trismus, uvular deviation, neck swelling, limited neck extension
Stridor at rest — at least moderate severity in croup and needs active treatment/observation
Normal oxygen saturation does not rule out upper airway danger early in the course
Approach to Investigation
First-line
Clinical airway assessmentLook from a distance first. Avoid distressing manoeuvres in suspected epiglottitis/critical obstruction. Assess voice, drooling, position, work of breathing, mental status, SpO2
No routine imaging for typical croupCroup is clinical. Neck X-ray may show steeple sign but is not needed and can delay care
Pulse oximetry and cardiorespiratory monitoringFor stridor at rest, moderate-severe croup, suspected anaphylaxis, or any unstable airway
Second-line
Flexible nasolaryngoscopyFor stable adult stridor, suspected supraglottitis, vocal cord dysfunction, tumour, or laryngeal pathology; perform in appropriate setting with airway support available
CXR / neck radiographsIf foreign body, bacterial tracheitis, retropharyngeal abscess, or alternative diagnosis suspected and patient stable
CT neck/chest with contrastFor suspected abscess, tumour, tracheal stenosis, or deep neck infection only when airway is stable
Specialist
Controlled airway evaluation in OR/ICUEpiglottitis, progressive angio-oedema, airway burn, unstable deep neck infection, or deteriorating stridor
Rigid bronchoscopySuspected foreign body aspiration or obstructing airway lesion
Management Principles
Canadian Paediatric Society/CAEP emergency airway principles + Canadian practice patterns1
Unstable upper airway
- Call anaesthesia/ENT/ICU/ED airway expertise immediately
- Keep patient upright and calm; do not force supine positioning or throat examination
- Provide oxygen if tolerated; prepare difficult airway equipment and surgical airway backup
- Treat immediately reversible causes: IM epinephrine for anaphylaxis, nebulised epinephrine for severe croup while arranging monitoring
2
Croup
- Dexamethasone single dose for all severities (oral preferred if tolerated)
- Nebulised epinephrine for moderate-severe croup or stridor at rest; observe for recurrence after effect wears off
- Avoid routine antibiotics, bronchodilators, CXR, or corticosteroid courses beyond guideline-based treatment in typical viral croup
3
Epiglottitis / bacterial tracheitis / deep neck infection
- Airway first; antibiotics after airway plan is secure if the patient is unstable
- Broad-spectrum IV antibiotics covering respiratory pathogens and oral flora depending on suspected syndrome and local guidance
- ENT/ICU admission; drainage for abscess when indicated
4
Anaphylaxis / angio-oedema
- IM epinephrine in the lateral thigh immediately for anaphylaxis; repeat every 5-15 minutes if needed
- Airway readiness for tongue/laryngeal swelling; antihistamines and steroids are adjuncts, not first-line lifesaving therapy
- ACE inhibitor angio-oedema may not respond to epinephrine if bradykinin-mediated, but airway protection remains the priority
Complications & Pitfalls
- Agitating epiglottitis: Forcing a throat exam or IV in a distressed child can precipitate complete airway obstruction.
- Confusing stridor with wheeze: Stridor is upper airway obstruction and needs a different urgency threshold.
- Delayed post-epinephrine observation: Nebulised epinephrine improves croup temporarily; observe for recurrence.
- Under-recognising adult epiglottitis: Adults may present less dramatically but can deteriorate quickly.
- Assuming normal SpO2 is safe: Upper airway obstruction can be severe before oxygen saturation falls.
MCCQE1 Exam Tips
- 1Drooling + tripod + muffled voice = epiglottitis. Do not examine the throat; call anaesthesia/ENT and secure airway in controlled setting
- 2Barking cough + hoarse voice + stridor = croup. Dexamethasone for all; nebulised epinephrine if stridor at rest/moderate-severe
- 3Toxic child with croup-like symptoms who does not improve with epinephrine = bacterial tracheitis
- 4Sudden onset during eating/play = foreign body; bronchoscopy is definitive
- 5Stridor after allergen/drug exposure with hypotension/urticaria = IM epinephrine first
- 6CanMEDS communicator: keeping the child with a caregiver and minimising distress is not cosmetic — it is airway management
practicetest your knowledge on stridorApply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — respiratory and beyond.
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