Croup (Laryngotracheobronchitis)

Quick Answer

Croup (Laryngotracheobronchitis) is an acute viral upper airway infection causing subglottic inflammation, classically presenting with barking cough, inspiratory stridor, and hoarse voice in children aged 6 months to 3 years.

Key Clinical Features:

• Viral prodrome (1-2 days of coryza, low-grade fever)
• Barking "seal-like" cough (hallmark)
• Inspiratory stridor (biphasic = severe)
• Hoarse voice
• Worse at night, often improves during day
• NO drooling (drooling suggests epiglottitis)

Emergency Management:

1. Keep child calm (crying worsens obstruction)
2. Dexamethasone 0.6 mg/kg PO/IV/IM (single dose) - ALL children with croup
3. Nebulized adrenaline 5 mL of 1:1000 (5 mg) for moderate-severe croup
4. Humidified oxygen if hypoxic (SpO2 <92%)
5. Intubation: Experienced operator, ETT 0.5-1.0 size smaller, ENT standby

ICU Mortality: <0.5% with appropriate management

Must-Know Facts:

• Narrowest point of paediatric airway is at the CRICOID cartilage (subglottic)
• 1 mm of edema reduces cross-sectional area by 44% and increases resistance 16-fold (Poiseuille's law)
• Parainfluenza virus types 1 and 3 cause 75% of cases
• Single-dose dexamethasone is standard of care (NNT 5 to prevent return to care)
• Nebulized adrenaline effect lasts 1-2 hours; observe for rebound
• Westley Croup Score guides severity assessment and disposition

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CICM Exam Focus

What Examiners Expect

Second Part Written (SAQ):

Common SAQ stems:

• "An 18-month-old child presents to the emergency department with stridor and barking cough. The child is distressed with marked chest wall recession. Describe your assessment and management."
• "A 2-year-old with croup has received nebulized adrenaline 30 minutes ago. The stridor has recurred. Outline your approach."
• "Discuss the indications for intubation in severe croup and describe the airway management strategy."
• "Compare and contrast croup with epiglottitis in a child presenting with stridor."

Expected depth:

• Westley Croup Score calculation and interpretation
• Poiseuille's law application to airway resistance (resistance ∝ 1/r⁴)
• Evidence base for corticosteroids (Cochrane review: Russell 2011)
• Nebulized adrenaline pharmacology and rebound phenomenon
• Intubation technique: smaller tube, experienced operator, ENT backup
• Differential diagnosis of upper airway obstruction

Second Part Hot Case:

Typical presentations:

• Child on humidified oxygen with residual stridor post-adrenaline - "Discuss your assessment and plan"
• Intubated child with severe croup - "What are your extubation criteria?"
• Child with atypical croup presentation - "What alternative diagnoses would you consider?"

Examiners assess:

• Systematic assessment of upper airway obstruction
• Recognition of impending respiratory failure
• Safe decision-making regarding intubation threshold
• Knowledge of airway management in upper airway obstruction
• Communication with family regarding severity and plan

Second Part Viva:

Expected discussion areas:

• Subglottic anatomy and Poiseuille's law
• Parainfluenza virus pathophysiology
• Evidence for dexamethasone and adrenaline
• Heliox mechanism (limited evidence)
• Indigenous health disparities in croup outcomes
• Remote/rural retrieval considerations

Common Mistakes

• Agitating the child (crying increases airway resistance by up to 50%)
• Using humidified air/mist therapy (no evidence of benefit, may worsen distress)
• Forgetting dexamethasone in mild croup (ALL children benefit)
• Not observing post-adrenaline for rebound (minimum 2-4 hours)
• Using standard ETT size (0.5-1 size down required)
• Not recognizing drooling as a red flag for alternative diagnosis (epiglottitis)

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Key Points

Must-Know Facts

1. Subglottic Anatomy is Critical: In children, the narrowest point of the airway is at the cricoid cartilage (subglottic), not the glottis as in adults. The adult larynx is widest at the cricoid. [1]

2. Poiseuille's Law: Airway resistance is inversely proportional to the fourth power of the radius (R ∝ 1/r⁴). In a 4 mm infant airway, 1 mm of edema reduces cross-sectional area by 44% and increases resistance 16-fold. [2]

3. Parainfluenza Dominates: Parainfluenza virus types 1 and 3 cause 75% of croup cases; other causes include influenza, RSV, adenovirus, human metapneumovirus, and rarely bacterial superinfection. [3]

4. Peak Age 6 Months - 3 Years: Croup predominantly affects children 6 months to 3 years (peak incidence 1-2 years). Males are 1.4x more commonly affected than females. [4]

5. Westley Croup Score: Validated severity score (0-17 points) assessing stridor, retractions, air entry, cyanosis, and level of consciousness. Score ≥8 = severe croup requiring ICU admission. [5]

6. Single-Dose Dexamethasone for ALL: Cochrane review (2011) confirms corticosteroids reduce symptoms at 6 and 12 hours, reduce return visits (NNT 5), and reduce admission rates. 0.6 mg/kg is standard. [6]

7. Nebulized Adrenaline: 5 mL of 1:1000 (5 mg) nebulized; causes alpha-adrenergic vasoconstriction reducing mucosal edema. Effect lasts 1-2 hours with potential rebound. [7]

8. Intubation in Severe Cases: 1-5% of hospitalized children require intubation. Use ETT 0.5-1 size smaller than age-calculated size; experienced operator essential; have ENT standby for surgical airway. [8]

9. Excellent Prognosis: ICU mortality <0.5% in developed countries. Most children recover completely within 2-7 days. Recurrent croup may indicate subglottic stenosis or other anatomical abnormality. [9]

10. Indigenous Health Disparity: Aboriginal and Torres Strait Islander children have 2-3x higher hospitalization rates for respiratory infections including croup, related to overcrowding, smoke exposure, and healthcare access. [10]

Memory Aids

Mnemonic "CROUP": Key Clinical Features

• C: Coryza prodrome (1-2 days)
• R: Retractions (chest wall)
• O: Onset at night (worse overnight)
• U: Upper airway stridor (inspiratory)
• P: Paroxysmal barking cough

Mnemonic "SAFE": When NOT to Discharge Post-Adrenaline

• S: Stridor at rest returns
• A: Accessory muscle use persists
• F: Four hours observation not complete
• E: Exhaustion or altered consciousness

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Definition & Epidemiology

Definition

Croup (Laryngotracheobronchitis) is defined as an acute viral infection of the upper respiratory tract causing inflammation of the larynx, trachea, and bronchi, with predominant involvement of the subglottic region resulting in characteristic stridor, barking cough, and hoarse voice. [11]

The Australasian Guidelines (2022) define croup as: "An acute viral upper airway infection characterized by the triad of barking cough, inspiratory stridor, and hoarse voice, occurring predominantly in children aged 6 months to 6 years."

Subtypes:

• Viral Croup (Laryngotracheobronchitis): Most common (95%); gradual onset with prodrome
• Spasmodic Croup: Sudden onset, usually at night; minimal prodrome; often recurrent
• Bacterial Tracheitis: Rare but severe; toxic appearance; poor response to steroids

Westley Croup Score (Validated Severity Assessment):

Severity Classification:

Epidemiology

International Data:

• Incidence: 3-6% of children aged 6 months to 6 years annually [12]
• Peak age: 6 months to 3 years (mean age 18 months)
• Male:Female ratio: 1.4:1
• Seasonal peak: Autumn/Winter (March-August in Australia)
• Hospitalization rate: 5-8% of children presenting to ED with croup
• ICU admission: 1-3% of hospitalized children
• Intubation rate: 1-5% of ICU admissions

Australian/NZ Data (ANZICS APD, state registries):

• Approximately 30,000-50,000 ED presentations annually in Australia
• Hospitalization rate 5-10% of ED presentations
• ICU admission rate decreasing with widespread dexamethasone use
• Peak incidence May-August (Australian winter)
• NSW data shows 3x higher rates in rural/remote areas

Risk Factors:

• Non-modifiable: Age 6 months - 3 years, male sex, family history of croup, history of neonatal intubation
• Modifiable: Environmental tobacco smoke exposure, lack of immunization, overcrowding
• Iatrogenic: Previous subglottic injury from intubation

High-Risk Populations:

• Aboriginal and Torres Strait Islander children: 2-3x higher hospitalization rates [13]
• Maori children: 1.5-2x higher rates
• Remote/rural populations: Delayed access to care, higher severity at presentation
• Children with Down syndrome: Smaller airways, increased susceptibility
• Children with previous subglottic stenosis

Aetiology:

Outcomes:

• ICU mortality: <0.5% in developed countries [14]
• Hospital mortality: <0.1%
• Duration of illness: 2-7 days (typically peaks Day 2-3)
• Recurrence: 5-10% have recurrent croup; consider anatomical abnormality if >3 episodes

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Applied Basic Sciences

This section bridges First Part basic sciences with Second Part clinical practice

Anatomy

Paediatric Airway Anatomy - Key Differences from Adults:

The paediatric airway differs significantly from the adult airway in ways that directly impact croup pathophysiology and management. [15]

Structural Differences:

Critical Point - Subglottic Anatomy:

The cricoid cartilage is the only complete cartilaginous ring in the airway. In children, this is the narrowest point of the upper airway:

• Neonate: 4-5 mm diameter
• 1 year: 5-6 mm diameter
• 3 years: 7-8 mm diameter
• Adult: 13-15 mm diameter

The subglottic space is lined by loose areolar tissue (pseudostratified columnar epithelium) that readily swells with inflammation. The cricoid ring cannot expand to accommodate this edema, making children uniquely vulnerable to subglottic obstruction. [16]

Surface Anatomy for Airway Procedures:

• Cricothyroid membrane: Between thyroid and cricoid cartilages (surgical cricothyroidotomy site)
• Sternal notch to carina: Approximately 4-5 cm in infants
• ETT depth (oral): Age/2 + 12 cm; confirm with auscultation and CXR

Physiology

Poiseuille's Law - Critical Concept for CICM Exam:

Poiseuille's Law describes the relationship between flow, pressure, and resistance in a tube: [17]

Q = \frac{\pi \cdot P \cdot r^4}{8 \cdot \eta \cdot l}

Where:

• Q = Flow rate
• P = Pressure gradient
• r = Radius of tube
• η = Viscosity of gas
• l = Length of tube

Key Implication: Resistance ∝ 1/r⁴

Clinical Application to Croup:

Stridor Physiology:

• Inspiratory stridor: Indicates extrathoracic obstruction (croup, epiglottitis, foreign body above carina)
  • During inspiration, negative intrathoracic pressure causes dynamic collapse of extrathoracic airways
• Expiratory stridor: Indicates intrathoracic obstruction (bronchiolitis, asthma, foreign body below carina)
  • During expiration, positive intrathoracic pressure compresses intrathoracic airways
• Biphasic stridor: Indicates FIXED or SEVERE obstruction - critical finding in croup

Work of Breathing:

• Increased airway resistance requires increased respiratory muscle effort
• Accessory muscle recruitment (sternocleidomastoid, scalenes)
• Subcostal, intercostal, suprasternal retractions
• Tracheal tug
• Fatigue eventually leads to respiratory failure with decreased effort (ominous sign)

Pathophysiology

Parainfluenza Virus Pathophysiology: [18]

Parainfluenza viruses (PIV) are enveloped, single-stranded RNA viruses of the Paramyxoviridae family.

Viral Attachment and Entry:

1. Hemagglutinin-neuraminidase (HN) protein binds sialic acid receptors on respiratory epithelium
2. Fusion (F) protein mediates viral-cell membrane fusion
3. Viral RNA enters cytoplasm for replication

Inflammatory Cascade:

1. Initial infection: PIV infects ciliated epithelial cells of larynx, trachea, bronchi
2. Epithelial damage: Cell death, sloughing of ciliated epithelium
3. Inflammatory response:
   • Neutrophil and lymphocyte infiltration
   • Pro-inflammatory cytokine release (IL-6, IL-8, TNF-α)
   • Submucosal edema (loose areolar tissue swells)
   • Increased mucus production
4. Subglottic narrowing:
   • Edema of subglottic mucosa
   • Fibrinous exudate
   • Impaired mucociliary clearance
   • Crusting and mucus plugging

Result: The "steeple sign" on AP neck X-ray represents subglottic narrowing from symmetrical mucosal edema.

Immune Response:

• T-cell mediated immunity is primary defense
• IgA provides mucosal protection
• Reinfection is common (incomplete immunity)
• Spasmodic croup may represent hyperreactive/allergic component

Pharmacology

Key ICU Drugs for Croup:

1. Dexamethasone: [19]

• Class: Glucocorticoid (synthetic)
• Mechanism:
  • Binds intracellular glucocorticoid receptors → translocates to nucleus
  • Inhibits pro-inflammatory gene transcription (IL-1, IL-6, TNF-α)
  • Reduces vascular permeability (decreases subglottic edema)
  • Inhibits prostaglandin and leukotriene synthesis
• ICU Indication: ALL children with croup (mild, moderate, severe)
• Dosing:
  • "Standard: 0.6 mg/kg PO/IV/IM (max 16 mg) - single dose"
  • "Lower dose may be effective: 0.15-0.3 mg/kg shown equivalent in some studies"
  • "Routes: PO preferred if tolerating (equivalent efficacy); IV/IM if unable to swallow"
• Onset: Clinical improvement within 1-2 hours; peak effect 6-12 hours
• Duration: Long half-life (36-72 hours) allows single-dose therapy
• Monitoring: Blood glucose (minimal effect with single dose)
• Adverse Effects: Rare with single dose; hyperglycemia, agitation
• Evidence: Cochrane review (Russell 2011) - NNT 5 to prevent return visit; NNT 8 to prevent hospitalization [6]

2. Nebulized Adrenaline (Epinephrine): [20]

• Class: Catecholamine (direct-acting sympathomimetic)
• Mechanism:
  • Alpha-1 receptor agonism on subglottic mucosal blood vessels
  • Vasoconstriction → reduced mucosal edema
  • Decreased airway resistance
• ICU Indication: Moderate-severe croup (Westley score ≥5); stridor at rest
• Dosing:
  • "Standard: 5 mL of 1:1000 (5 mg) via nebulizer"
  • "Alternative: 0.5 mL/kg of 1:1000 (max 5 mL)"
  • L-adrenaline and racemic adrenaline are equally effective
• Onset: 10-30 minutes
• Duration: 1-2 hours (CRITICAL - rebound phenomenon)
• Monitoring: Heart rate, blood pressure, ECG (tachyarrhythmias)
• Adverse Effects: Tachycardia, pallor, tremor, hypertension
• Rebound Phenomenon: Symptoms may return after 1-2 hours as vasoconstrictor effect wanes; children must be observed for minimum 2-4 hours post-nebulization [21]
• Evidence: Cochrane review (Bjornson 2013) - significant improvement in croup score at 30 minutes; no evidence of rebound worsening beyond baseline [7]

3. Budesonide (Nebulized): [22]

• Class: Inhaled corticosteroid
• Mechanism: Same as dexamethasone but topical delivery
• ICU Indication: Alternative if unable to take oral dexamethasone
• Dosing: 2 mg nebulized (single dose)
• Onset: 2-4 hours
• Evidence: Equivalent to oral dexamethasone; more expensive; may be useful if vomiting prevents oral intake
• Limitation: Requires nebulizer; may agitate child

4. Heliox (Helium-Oxygen Mixture): [23]

• Class: Medical gas
• Mechanism:
  • Helium is less dense than nitrogen (density 0.18 vs 1.25 g/L)
  • Lower density reduces turbulent flow in narrowed airway
  • Converts turbulent flow to laminar flow
  • Reduces work of breathing
• ICU Indication: Severe croup as bridge while awaiting steroid effect; alternative to intubation
• Dosing: 70:30 or 80:20 helium:oxygen mixture
• Onset: Immediate
• Limitation: Limits FiO2 to 0.2-0.3 (not suitable if hypoxic); requires special equipment; limited evidence
• Evidence: Limited RCT data; theoretical benefit; may be useful as temporizing measure [24]

Pathology

Histopathology of Croup: [25]

• Epithelium: Necrosis and desquamation of ciliated columnar epithelium
• Submucosa: Edema and inflammatory cell infiltration (lymphocytes, neutrophils)
• Mucus: Increased goblet cell activity; thick mucoid secretions
• Fibrinous exudate: May form pseudomembranes (especially in bacterial tracheitis)
• Blood vessels: Vasodilation and increased permeability

Contrast with Epiglottitis:

• Epiglottitis: Intense supraglottic cellulitis with edema of aryepiglottic folds
• Abscess formation common in epiglottitis (rare in croup)
• Croup: Subglottic predominant inflammation

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Clinical Presentation

ICU Admission Scenarios

Typical Presentations:

Scenario 1: Moderate-Severe Croup

• 18-month-old male, 48 hours of coryza, now with barking cough and stridor
• Parents report worsening overnight despite GP dexamethasone 12 hours ago
• Examination: Tachypnoeic, moderate intercostal recession, inspiratory stridor at rest
• Westley Score: 6 (stridor at rest 2, moderate retractions 2, decreased air entry 2)
• Management: Nebulized adrenaline, observation, consider ICU if recurrent stridor

Scenario 2: Severe Croup with Impending Respiratory Failure

• 2-year-old Aboriginal female from remote community, transferred by RFDS
• Delayed presentation due to access issues
• Examination: Exhausted, minimal respiratory effort, biphasic stridor, drowsy
• Westley Score: 12 (stridor at rest 2, severe retractions 3, marked decrease in air entry 2, altered consciousness 5)
• Management: Immediate ICU, prepare for intubation, ENT standby

Scenario 3: Post-Intubation Croup (For Extubation Planning)

• 15-month-old post-RSV bronchiolitis, extubated 24 hours ago
• Developing stridor and increased work of breathing
• Consideration: Post-extubation croup vs laryngeal edema vs subglottic stenosis
• Management: Dexamethasone, adrenaline, close monitoring, may require reintubation

Symptoms & Signs

History:

• Prodrome: 1-2 days of coryza, mild fever (usually <39°C)
• Chief complaint: "Barking" or "seal-like" cough (pathognomonic)
• Stridor: Initially with agitation/crying, then at rest (increasing severity)
• Hoarse voice: Due to laryngeal involvement
• Time course: Symptoms typically worst on Day 2-3; worse at night
• No drooling: Drooling suggests epiglottitis or retropharyngeal abscess
• No significant dysphagia: Eating/drinking usually preserved unless severe

Red Flag Features (Consider Alternative Diagnosis):

• Drooling or dysphagia (epiglottitis, retropharyngeal abscess)
• Toxic appearance (bacterial tracheitis, epiglottitis)
• High fever >40°C (bacterial infection)
• No response to dexamethasone (alternative diagnosis)
• Sudden onset without prodrome (foreign body)
• Unilateral findings (unilateral obstruction)

Examination:

General:

• Appearance: Anxious but alert (altered consciousness is ominous)
• Position: Prefers sitting upright
• Vital signs: Tachypnoea, tachycardia; hypoxia is late sign

A - Airway:

• Stridor: Inspiratory (mild-moderate) → Biphasic (severe)
• Voice: Hoarse, weak cry
• Cough: Barking, paroxysmal
• Drooling: ABSENT (present = epiglottitis)

B - Breathing:

• Respiratory rate: Elevated (age-appropriate normal + 20-40%)
• Work of breathing:
  • Subcostal recession
  • Intercostal recession
  • Suprasternal recession
  • Tracheal tug
  • Nasal flaring
• Auscultation: Transmitted upper airway sounds; lung fields usually clear
• Oxygen saturation: Usually >92% unless severe

C - Circulation:

• Heart rate: Elevated (stress response, hypoxia)
• Blood pressure: Usually normal
• Perfusion: Usually maintained
• Pallor: May indicate hypoxia or distress

D - Disability/Neurology:

• GCS/AVPU: Alert is normal; any decrease is critical
• Agitation: Early sign of hypoxia
• Lethargy: Late, ominous sign of respiratory failure

E - Exposure/Everything Else:

• Temperature: Low-grade fever (<39°C); high fever suggests bacterial superinfection
• Skin: No rashes (rash may suggest measles croup)
• Hydration: May be dehydrated from poor intake

Severity Scoring

Westley Croup Score (Maximum 17 points): [5]

Interpretation:

• 0-2: Mild - Discharge home with dexamethasone
• 3-5: Moderate - Observation, dexamethasone, may need adrenaline
• 6-11: Moderate-Severe - Dexamethasone + adrenaline, ICU consideration
• ≥12: Severe - ICU admission, prepare for intubation

Differential Diagnosis

Upper Airway Obstruction - Critical Differentials:

"Must Not Miss" Diagnoses:

1. Epiglottitis: Drooling, toxic, NEVER examine throat; immediate senior involvement
2. Foreign Body: Sudden onset, witnessed choking; may need rigid bronchoscopy
3. Bacterial Tracheitis: Toxic, purulent secretions; antibiotics essential

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Investigations

Laboratory Investigations

Bedside Tests:

Blood Gas Analysis (if severe/impending respiratory failure):

• pH: Usually normal or mild respiratory alkalosis (hyperventilation)
• PaCO2: Rising PaCO2 indicates impending respiratory failure (ominous)
• PaO2: Hypoxia is a late sign
• Lactate: Usually normal; elevated suggests severe distress

Croup is a CLINICAL DIAGNOSIS - Investigations are LIMITED:

• Most children with mild-moderate croup require NO investigations
• Do NOT perform investigations that may upset the child and worsen obstruction

Blood Tests (Only if Severe or Diagnostic Uncertainty):

• FBC: Lymphocytosis (viral infection); neutrophilia may suggest bacterial superinfection
• CRP: Usually mildly elevated; high CRP suggests bacterial infection
• Blood cultures: Only if bacterial infection suspected

Viral Studies:

• Nasopharyngeal swab for viral PCR (not routinely required)
• May be useful for infection control (cohorting) and epidemiology
• Parainfluenza, influenza, RSV, adenovirus, SARS-CoV-2

Imaging

Soft Tissue Neck X-Ray (Rarely Indicated): [26]

• AP View - "Steeple Sign" or "Pencil Sign":

  • Subglottic narrowing creating pencil-point appearance
  • Symmetrical narrowing of subglottic airway
  • 50% sensitivity (normal X-ray does NOT exclude croup)

• Lateral View:

  • Normal epiglottis (rules out epiglottitis)
  • Subglottic haziness/narrowing

• Indications for X-Ray:

  • Atypical presentation
  • Suspected foreign body
  • Suspected epiglottitis (lateral neck X-ray - "thumb sign")
  • No response to treatment
  • Recurrent croup (to assess for subglottic stenosis)

• CAUTION: X-rays should NOT delay treatment; child should be accompanied by senior medical staff and equipment for emergency airway management

CT/MRI: Rarely indicated; only for suspected structural abnormality or abscess

Laryngoscopy/Bronchoscopy: [27]

• Indicated if:
  • Recurrent croup (>3 episodes)
  • No response to steroids
  • Suspected structural abnormality
  • Suspected foreign body
• Reveals subglottic edema, stenosis, or alternative pathology

Physiological Monitoring

Non-Invasive Monitoring:

• Continuous pulse oximetry: Target SpO2 ≥92%
• Cardiorespiratory monitoring: HR, RR
• Observation of work of breathing (visual assessment)

Key Principle: Minimize disturbance to the child

• Crying/distress increases airway resistance by up to 50%
• Parental presence reduces distress
• Continuous SpO2 monitoring is sufficient in most cases
• Avoid repeated examinations

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ICU Management

This is the core clinical section

Initial Resuscitation (First Hour)

A - Airway:

Assessment:

• Stridor characteristics: Inspiratory vs biphasic
• Work of breathing: Retractions, accessory muscle use
• Air entry: Decreased indicates severe obstruction
• Consciousness: Altered = impending failure

Keep Child Calm:

• Allow parental presence/cuddles
• Minimize interventions
• Avoid blood tests/IV unless essential
• Do NOT examine throat with spatula

Airway Interventions:

Humidified Oxygen:

• Indication: SpO2 <92%
• Delivery: Blow-by oxygen, face mask (tolerated), or HFNC
• Target: SpO2 ≥92%
• Note: Humidified air/mist therapy has NO proven benefit [28]

B - Breathing:

Nebulized Adrenaline (Moderate-Severe Croup):

• Indication: Westley score ≥5, stridor at rest, significant retractions
• Dose: 5 mL of 1:1000 adrenaline (5 mg) via nebulizer
• Delivery: Oxygen-driven nebulizer (6-8 L/min); parent may hold mask
• Onset: 10-30 minutes
• Duration: 1-2 hours
• Repeat: May repeat every 20-30 minutes if needed (maximum 3 doses before considering intubation)
• Post-nebulizer Observation: Minimum 2-4 hours for rebound [21]

C - Circulation:

• Usually stable in croup
• IV access: Only if severe or for dexamethasone IV
• Fluid bolus: Only if signs of dehydration/poor perfusion (rare)

D - Disability:

• GCS/AVPU monitoring
• Blood glucose: Check if altered consciousness

E - Everything Else:

Dexamethasone (ALL Children with Croup): [29]

• Dose: 0.6 mg/kg (maximum 16 mg)
• Route: PO (preferred) > IV > IM
• Timing: As soon as possible after diagnosis
• Single dose is standard (long half-life 36-72 hours)
• Alternative: Nebulized budesonide 2 mg (if unable to take PO)

Definitive Management (First 24-48 Hours)

Observation and Monitoring:

• Regular Westley score assessment (Q1-2 hourly)
• Continuous SpO2
• Minimize disturbance
• Parental presence

Escalation Algorithm:

Mild Croup (Score 0-2)
    └── Dexamethasone 0.6 mg/kg PO → Observe 2-4 hours → Discharge home

Moderate Croup (Score 3-7)
    └── Dexamethasone 0.6 mg/kg 
    └── Consider nebulized adrenaline if stridor at rest
    └── Observe 4+ hours post-adrenaline
    └── Admit if persistent symptoms

Severe Croup (Score 8-11)
    └── Dexamethasone 0.6 mg/kg IV/IM
    └── Nebulized adrenaline 5 mg (may repeat x3)
    └── ICU admission
    └── Heliox consideration
    └── Prepare for intubation if worsening

Impending Respiratory Failure (Score ≥12)
    └── ICU admission
    └── Senior airway team (Intensivist + Anaesthetist + ENT)
    └── Dexamethasone + repeated adrenaline as bridge
    └── Intubation preparation
    └── ENT standby for surgical airway

Heliox (Helium-Oxygen Mixture): [24]

• Composition: 70:30 or 80:20 helium:oxygen
• Indication: Severe croup as temporizing measure; bridge to steroid effect
• Mechanism: Reduces turbulent flow in narrowed airway
• Limitation:
  • Limits FiO2 to 0.2-0.3 (contraindicated if hypoxic)
  • Limited evidence (Cochrane inconclusive)
  • Requires specialized equipment
• Duration: Continue until clinical improvement from steroids

Intubation in Severe Croup

Indications for Intubation: [30]

• Altered level of consciousness
• Cyanosis or severe hypoxia despite oxygen
• Exhaustion with decreasing respiratory effort
• No improvement after 3 doses of nebulized adrenaline
• Apnoea

Intubation Strategy:

Pre-Intubation Preparation:

1. Senior operator: Most experienced person available (Intensivist/Anaesthetist)
2. ENT surgeon: Standby for surgical airway (tracheostomy)
3. Location: Operating theatre or PICU (NOT ED if possible)
4. Equipment:
   • Video laryngoscope (preferred)
   • Multiple ETT sizes: Calculate age-appropriate MINUS 0.5-1.0 size
   • Stylet available
   • Surgical airway kit available
5. Drugs: Minimize muscle relaxant if possible (maintain spontaneous ventilation)

ETT Size Selection:

Formula: Cuffed ETT = (Age/4) + 3.5 - 0.5 to 1.0

Induction Options:

1. Gas induction (sevoflurane): Preferred in croup; maintains spontaneous ventilation; gives time for assessment
2. IV induction with ketamine: Maintains airway tone; bronchodilator properties
3. Avoid muscle relaxants initially: May cause complete obstruction if cannot ventilate

Post-Intubation Management:

• Confirm ETT position: Auscultation, EtCO2, CXR
• Secure ETT firmly
• Light sedation (propofol infusion or midazolam)
• Continue dexamethasone
• Humidified ventilation
• Consider cuff leak test before extubation (air leak at 20-30 cmH2O)

Duration of Intubation: Typically 24-72 hours until edema resolves

Ongoing ICU Care (Beyond 48 Hours)

Daily Management:

• Assess for extubation readiness
• Cuff leak test (positive leak = likely safe to extubate)
• Dexamethasone may be repeated pre-extubation
• ENT standby for extubation in severe cases

Extubation Criteria:

• Afebrile
• Cuff leak present
• Improved secretions
• Reduced ventilator support requirements
• Dexamethasone pre-extubation (some centres)
• Senior staff available

Failed Extubation Protocol:

• Nebulized adrenaline immediately
• Re-intubate if no improvement
• Consider ENT assessment for subglottic stenosis
• Plan for tracheostomy if repeated failure

Australian-Specific Protocols

ANZICS/Australasian Guidelines: [31]

• Single-dose dexamethasone 0.6 mg/kg for ALL croup (mild, moderate, severe)
• Nebulized adrenaline for moderate-severe croup
• Observation period 2-4 hours post-adrenaline
• ICU admission for severe croup (Westley ≥8) or impending respiratory failure

Indigenous Health Considerations: [13]

Aboriginal and Torres Strait Islander children experience:

• 2-3x higher hospitalization rates for respiratory infections
• Increased severity at presentation (delayed access)
• Remote communities may have limited medical resources

Best Practice:

• Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO)
• Include extended family in discussions
• Consider cultural protocols (e.g., Sorry Business)
• Provide clear, culturally appropriate discharge information
• Low threshold for retrieval to tertiary centre

Maori Health Considerations:

• Involve whanau (extended family) in decision-making
• Maori Health Workers may facilitate communication
• Respect for tikanga (cultural customs)

Remote/Rural Retrieval:

• Early contact with PICU and retrieval services
  • "NSW: NETS (Newborn and Paediatric Emergency Transport Service)"
  • "Victoria: PIPER"
  • "Queensland: RSQ"
  • "National: RFDS"
• Dexamethasone should be administered before retrieval
• Nebulized adrenaline for severe cases
• Consider intubation before retrieval if prolonged transport and severe disease
• Heliox typically not available in remote settings

---

Monitoring & Complications

ICU-Specific Monitoring

Daily Parameters:

• Westley Croup Score: Q1-2 hourly initially, then Q4 hourly
• Continuous SpO2
• Cardiorespiratory monitoring
• Parental/nursing observation of work of breathing

Trend Monitoring:

• Stridor characteristics (improving/worsening)
• Work of breathing (decreasing retractions = improvement)
• Response to adrenaline (duration of effect)
• Feeding tolerance (marker of improvement)

Post-Adrenaline Monitoring:

• Observe for minimum 2-4 hours
• Document time of nebulization
• Assess for rebound at 60-120 minutes

Complications

Early Complications (First 24-48 hours):

Complication 1: Adrenaline Rebound

• Incidence: Symptoms return in 30-50% within 2 hours
• Risk factors: Severe initial presentation, short duration of initial response
• Presentation: Recurrence of stridor and work of breathing
• Prevention: Adequate observation period (2-4 hours)
• Management: Repeat nebulized adrenaline; consider escalation [32]

Complication 2: Respiratory Failure

• Incidence: <5% of hospitalized children
• Risk factors: Severe initial presentation, young age, delayed presentation
• Presentation: Exhaustion, decreasing respiratory effort, altered consciousness
• Prevention: Early escalation, adequate treatment
• Management: Intubation with appropriate precautions

Complication 3: Hypoxic Brain Injury

• Incidence: Very rare (<0.1%)
• Risk factors: Delayed presentation, failed intubation
• Prevention: Early recognition, experienced airway management

Late Complications (Beyond 48 hours):

Complication 4: Post-Extubation Stridor

• Incidence: 5-15% after intubation for croup
• Risk factors: Traumatic intubation, prolonged intubation, multiple intubation attempts
• Presentation: Stridor within 4-24 hours of extubation
• Prevention: Smaller ETT, dexamethasone pre-extubation, cuff leak test
• Management: Nebulized adrenaline, reintubation if severe [33]

Complication 5: Subglottic Stenosis

• Incidence: Rare; more common with traumatic/prolonged intubation
• Risk factors: ETT too large, prolonged intubation, repeated intubation
• Presentation: Recurrent croup, persistent stridor, exercise intolerance
• Prevention: Appropriate ETT size, limit intubation duration
• Management: ENT referral, may require laryngotracheal reconstruction

Complication 6: Bacterial Tracheitis (Superinfection)

• Incidence: <1% of croup cases
• Pathogens: Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae
• Risk factors: Prolonged illness, no improvement with steroids
• Presentation: Toxic appearance, high fever, purulent secretions
• Management: IV antibiotics, possible intubation [34]

ICU-Acquired Complications:

• IV line infection (if IV access obtained)
• Adverse drug reactions (rare)
• Parental anxiety/distress

---

Prognosis & Outcome Measures

Mortality

Short-Term Outcomes:

• ICU mortality: <0.5% in developed countries [14]
• Hospital mortality: <0.1%
• Mortality virtually eliminated with corticosteroid therapy

Historical Context:

• Pre-corticosteroid era mortality: 2-3%
• Dramatic improvement with widespread dexamethasone use

Morbidity

Functional Recovery:

• Complete recovery: >95% within 7 days
• Recurrent croup: 5-10% of children
• Significant long-term morbidity: Very rare

Outcomes by Severity:

Prognostic Factors

Good Prognostic Factors:

• Age >1 year
• Mild initial presentation
• Good response to dexamethasone
• First episode of croup
• No underlying airway abnormality
• Early presentation and treatment

Poor Prognostic Factors:

• Age <6 months
• Previous intubation
• Down syndrome (smaller airways)
• Severe initial presentation (Westley ≥8)
• No response to dexamethasone (consider alternative diagnosis)
• Recurrent croup (may indicate structural abnormality)
• Remote location/delayed access to care

Recurrent Croup

Definition: ≥2 episodes of croup

Evaluation Required:

• ENT referral for laryngoscopy/bronchoscopy
• Consider subglottic stenosis, laryngomalacia, vocal cord dysfunction
• Assess for GORD (may contribute to airway inflammation)
• Allergy evaluation (spasmodic croup may have allergic component)

Australian/NZ Outcome Data

ANZICS APD Data:

• ICU mortality <0.5% nationally
• Average ICU LOS: 1-2 days
• Intubation rate declining with early dexamethasone use

Indigenous Health Outcomes: [13]

• Higher hospitalization rates (2-3x)
• More severe presentations at admission
• Longer hospital stays
• Related to social determinants (overcrowding, smoke exposure, access)

---

SAQ Practice

SAQ 1: Severe Croup Management

Time Allocation: 10 minutes
Total Marks: 20

Stem: An 18-month-old boy is brought to the emergency department at 2 AM by his parents. He has had a "cold" for 2 days and developed a barking cough at bedtime. He is now stridulous at rest. The parents are distressed.

Observations on arrival:

• HR: 160/min
• RR: 40/min
• SpO2: 92% on room air
• Temperature: 38.2°C
• Weight: 12 kg

On examination, he has marked subcostal and intercostal recession, inspiratory stridor at rest, and decreased air entry bilaterally. He is anxious but alert and responds appropriately to his parents.

---

Question 1.1 (8 marks)

Calculate the Westley Croup Score and describe your immediate management in the first 30 minutes.

Question 1.2 (6 marks)

The child receives nebulized adrenaline and shows initial improvement. Thirty minutes later, stridor at rest recurs. Describe your ongoing management and criteria for ICU admission.

Question 1.3 (6 marks)

Discuss the indications for intubation in croup and describe your approach to securing the airway in this child if required.

---

Model Answer

Question 1.1 (8 marks total)

Westley Croup Score Calculation (3 marks):

• Stridor at rest: 2 points
• Subcostal/intercostal recession (moderate-severe): 2-3 points
• Decreased air entry: 2 points
• Cyanosis: 0 points (SpO2 92%)
• Level of consciousness: Normal: 0 points

Total Score: 6-7 (Moderate-Severe Croup) (1 mark)

Immediate Management (5 marks):

A - Airway (1 mark):

• Keep child calm; allow parental cuddles
• Do NOT examine oropharynx (avoid agitating child)
• Minimize interventions

B - Breathing (2 marks):

• Humidified oxygen via blow-by or mask if tolerated to maintain SpO2 ≥92%
• Nebulized adrenaline 5 mL of 1:1000 (5 mg) via oxygen-driven nebulizer

C - Circulation (0.5 marks):

• IV access only if needed for dexamethasone (avoid if PO possible)

E - Everything Else (1.5 marks):

• Dexamethasone 0.6 mg/kg = 7.2 mg (round to 8 mg) PO/IV
• Single dose (long half-life allows one-time dosing)
• Contact PICU if severe features present

---

Question 1.2 (6 marks total)

Recurrent Stridor Post-Adrenaline (2 marks):

• This represents the "rebound" phenomenon
• Alpha-adrenergic vasoconstriction effect wears off (duration 1-2 hours)
• Reassess Westley Score
• Child must NOT be discharged; requires observation

Ongoing Management (2 marks):

• Repeat nebulized adrenaline 5 mg (can repeat up to 3 doses)
• Ensure dexamethasone has been given (effect peaks at 6-12 hours)
• Continue humidified oxygen
• Reassess after each adrenaline dose

Criteria for ICU Admission (2 marks):

• Westley Score ≥8
• Stridor at rest persisting despite 2+ doses of adrenaline
• Hypoxia (SpO2 <92%) despite oxygen
• Altered level of consciousness
• Exhaustion or decreasing respiratory effort
• Need for frequent nebulized adrenaline (>3 doses)
• Parental concern or complex social situation

---

Question 1.3 (6 marks total)

Indications for Intubation (2 marks):

• Altered level of consciousness
• Cyanosis or severe hypoxia despite oxygen
• Exhaustion with decreasing respiratory effort
• No improvement after 3 doses of nebulized adrenaline
• Apnoea
• Clinical judgment of impending respiratory failure

Approach to Airway Management (4 marks):

Preparation (1 mark):

• Senior operator (most experienced Intensivist/Anaesthetist available)
• ENT surgeon on standby for surgical airway
• Location: Theatre or PICU (controlled environment)
• Equipment: Video laryngoscope, multiple ETT sizes, surgical airway kit

ETT Size (1 mark):

• Normal size for 18 months: 3.5-4.0 mm cuffed
• Use 0.5-1 size smaller: 3.0-3.5 mm cuffed
• Subglottic edema narrows airway

Induction Technique (1 mark):

• Preferred: Gas induction with sevoflurane (maintains spontaneous ventilation)
• Alternative: IV ketamine (maintains airway tone)
• Avoid muscle relaxants initially (may cause complete obstruction)

Post-Intubation (1 mark):

• Confirm position (auscultation, EtCO2, CXR)
• Secure tube firmly
• Continue dexamethasone
• Light sedation
• Plan for extubation in 24-72 hours once edema resolved

---

Common Mistakes:

• Not keeping the child calm (agitation worsens obstruction)
• Forgetting to calculate Westley Score
• Not repeating adrenaline when stridor recurs
• Using standard ETT size (risk of subglottic trauma)
• Not having ENT backup for intubation

Examiner Comments:

• Good candidates demonstrate systematic approach and knowledge of pathophysiology
• Pass candidates calculate Westley Score correctly and recognize severity
• Fail candidates attempt throat examination or use inappropriate ETT size

---

SAQ 2: Failed Intubation in Croup

Time Allocation: 10 minutes
Total Marks: 20

Stem: You are the PICU consultant called to the operating theatre. A 2-year-old girl with severe croup has had a failed intubation attempt by the anaesthetist. She was brought to theatre for gas induction after failing to respond to three doses of nebulized adrenaline in the emergency department.

The first intubation attempt with a 4.0 mm cuffed ETT was unsuccessful - the tube would not pass through the subglottic region. The child is currently being bag-mask ventilated with difficulty and oxygen saturation is 85%.

Available resources:

• Anaesthetist with video laryngoscope
• ENT surgeon has been called
• Smaller ETT sizes available
• Surgical airway kit available

---

Question 2.1 (8 marks)

Describe your immediate actions and the options for managing this failed intubation.

Question 2.2 (6 marks)

The ENT surgeon arrives. Discuss the surgical airway options in a 2-year-old and the considerations for each approach.

Question 2.3 (6 marks)

The child is successfully intubated with a 3.0 mm ETT after a second attempt. Describe your post-intubation management plan and considerations for extubation.

---

Model Answer

Question 2.1 (8 marks total)

Immediate Actions (4 marks):

Call for Help (1 mark):

• Confirm ENT surgeon en route (surgical airway backup)
• Additional anaesthesia assistance
• Prepare surgical airway equipment

Optimize Oxygenation (1 mark):

• Continue bag-mask ventilation with two-person technique
• 100% FiO2
• Consider oropharyngeal airway to improve mask ventilation
• Position: Neutral position with jaw thrust

Prepare for Second Attempt (1 mark):

• Use SMALLER ETT: 3.0 mm or 3.5 mm (not 4.0 mm)
• Video laryngoscopy (best view)
• Stylet loaded
• Limit to ONE further attempt before surgical airway

Avoid Further Trauma (1 mark):

• Multiple attempts worsen edema
• If second attempt fails, proceed to surgical airway
• Avoid repeat attempts with same size tube

Options for Failed Intubation (4 marks):

1. Smaller ETT (3.0-3.5 mm) via laryngoscopy (1 mark):

   • Most likely to succeed
   • Video laryngoscopy preferred
   • Single attempt

2. Supraglottic Airway Device (1 mark):

   • LMA as rescue device for oxygenation
   • May not ventilate effectively with subglottic obstruction
   • Temporizing measure only

3. Surgical Airway (1 mark):

   • Tracheostomy (preferred in children)
   • Cricothyroidotomy (technically difficult in children <10 years)
   • Needle cricothyroidotomy with jet ventilation (temporizing)

4. Awaken and Maintain Spontaneous Ventilation (1 mark):

   • If can oxygenate with mask, may allow gas induction to wear off
   • Continue adrenaline nebulization
   • Plan elective surgical airway when stable

---

Question 2.2 (6 marks total)

Surgical Airway Options in a 2-Year-Old:

Tracheostomy (Preferred in Children) (3 marks):

• Technique: Surgical dissection, incision between 2nd-3rd tracheal rings
• Advantages:
  • Familiar to ENT surgeons
  • Definitive airway
  • More secure than cricothyroidotomy
  • Can be performed awake under local anaesthesia if needed
• Disadvantages:
  • Takes 5-10 minutes
  • Requires surgical expertise
  • Risk of tracheal stenosis, bleeding, pneumothorax
• Considerations:
  • May be life-saving if intubation impossible
  • ENT surgeon availability essential

Cricothyroidotomy (2 marks):

• Technique: Incision through cricothyroid membrane
• Limitations in Children:
  • Small cricothyroid membrane (difficult to locate and puncture)
  • Risk of subglottic stenosis (below vocal cords)
  • Not recommended in children <10-12 years
• Alternative: Needle Cricothyroidotomy:
  • 14-16 gauge cannula through cricothyroid membrane
  • Connect to jet ventilator (intermittent high-pressure oxygen)
  • Temporizing measure only (10-30 minutes maximum)
  • Risk of barotrauma

Front of Neck Access (FONA) Considerations (1 mark):

• In paediatrics, tracheostomy is preferred over cricothyroidotomy
• Needle cricothyroidotomy as bridge to tracheostomy if critical hypoxia
• Always maintain attempt at bag-mask ventilation while preparing surgical airway

---

Question 2.3 (6 marks total)

Post-Intubation Management Plan (4 marks):

Immediate Post-Intubation (1 mark):

• Confirm ETT position: Auscultation, EtCO2, CXR
• Note ETT depth at lips
• Secure tube securely (tape and ties)

ICU Management (2 marks):

• Sedation: Propofol or midazolam infusion (light sedation)
• Analgesia: Fentanyl infusion
• Continue dexamethasone 0.6 mg/kg daily (some protocols continue for 24-48 hours)
• Humidified ventilation
• Minimal handling to prevent accidental extubation

Monitoring (1 mark):

• Continuous SpO2, HR, BP
• ETT position on daily CXR
• Secretions (may indicate improving or worsening)
• Daily sedation holds to assess readiness

Extubation Considerations (2 marks):

Criteria for Extubation (1 mark):

• Afebrile
• Decreasing secretions
• Cuff leak test positive (air leak at 20-30 cmH2O suggests adequate space around tube)
• At least 24-48 hours post-intubation (allow edema to resolve)
• Senior staff available for extubation

Preparation for Extubation (1 mark):

• Pre-extubation dexamethasone (some protocols give 6-12 hours before)
• Nebulized adrenaline immediately available post-extubation
• Reintubation equipment ready
• Consider ENT standby if difficult intubation
• Plan extubation early in the day when full team available

---

Common Mistakes:

• Using same ETT size for repeat attempt
• Multiple intubation attempts (worsens edema)
• Attempting cricothyroidotomy in young children
• Not having surgical airway backup

Examiner Comments:

• Good candidates recognize the importance of smaller ETT and surgical backup
• Pass candidates discuss tracheostomy as preferred surgical option in children
• Fail candidates attempt multiple intubations with same size tube

---

Viva Scenarios

Viva Scenario 1: Nebulized Adrenaline Use

Stem: "A 20-month-old boy presents to the emergency department with croup. He has inspiratory stridor at rest and moderate chest wall retractions. You administer nebulized adrenaline. Let's discuss this treatment."

Duration: 12 minutes

---

Examiner: "What is the mechanism of action of nebulized adrenaline in croup?"

Candidate: "Nebulized adrenaline works primarily through alpha-1 adrenergic receptor agonism on the blood vessels supplying the subglottic mucosa.

Adrenaline causes vasoconstriction of these vessels, which reduces:

1. Blood flow to the edematous subglottic tissue
2. Transudation of fluid from vessels into the interstitium
3. Overall mucosal swelling

The result is reduced subglottic edema and decreased airway resistance. According to Poiseuille's law, even a small increase in airway radius dramatically reduces resistance - resistance is inversely proportional to the fourth power of the radius.

The onset of action is 10-30 minutes, with peak effect at about 30 minutes. However, the duration is only 1-2 hours, which is important clinically."

---

Examiner: "What dose do you use and how do you administer it?"

Candidate: "The standard dose is 5 mL of 1:1000 adrenaline, which equals 5 mg of adrenaline.

Administration is via oxygen-driven nebulizer at 6-8 L/min flow rate. The parent can hold the mask near the child's face to minimize distress - a crying child has increased airway resistance.

An alternative dosing regimen is 0.5 mL/kg of 1:1000 solution up to a maximum of 5 mL.

Both L-adrenaline (what we use in Australia) and racemic adrenaline have been studied - they are equally effective. Racemic adrenaline was historically used in North America, but L-adrenaline is now standard.

The Cochrane review by Bjornson in 2013 confirmed significant improvement in croup score at 30 minutes with nebulized adrenaline."

---

Examiner: "The child improves initially but 90 minutes later the stridor returns. What is happening and how do you manage this?"

Candidate: "This is the adrenaline rebound phenomenon. As the alpha-adrenergic vasoconstrictor effect wears off after 1-2 hours, the underlying mucosal edema and inflammation persists, and symptoms recur.

This is why the Cochrane review found no evidence that patients were actually worse than baseline after rebound - they simply return to their pre-treatment state.

Management:

1. Reassess the Westley Score
2. Repeat nebulized adrenaline - can be given every 20-30 minutes if needed
3. Ensure dexamethasone has been administered (steroid effect takes 2-6 hours)
4. Continue close observation
5. Consider ICU admission if requiring multiple adrenaline doses

The critical point is that this child CANNOT be discharged. Any child who receives nebulized adrenaline must be observed for a minimum of 2-4 hours after the last dose to assess for rebound.

If the child requires more than 3 doses of adrenaline without sustained improvement, I would escalate to ICU and prepare for possible intubation."

---

Examiner: "What is the role of corticosteroids and how do they differ from adrenaline?"

Candidate: "Corticosteroids, specifically dexamethasone, are the cornerstone of croup management and should be given to ALL children with croup regardless of severity.

The mechanism is anti-inflammatory:

• Dexamethasone binds intracellular glucocorticoid receptors
• This inhibits pro-inflammatory gene transcription
• Reduces vascular permeability
• Decreases subglottic edema

Key differences from adrenaline:

The Cochrane review by Russell in 2011 found dexamethasone:

• NNT 5 to prevent return visit
• NNT 8 to prevent hospitalization
• Reduces symptoms at 6, 12, and 24 hours

Standard dose is 0.6 mg/kg oral or IV, single dose. The long half-life means single-dose therapy is adequate."

---

Examiner: "What if the child cannot take oral dexamethasone?"

Candidate: "There are several alternatives:

1. Intravenous dexamethasone - Same dose (0.6 mg/kg), immediate onset, requires IV access

2. Intramuscular dexamethasone - Same dose, effective, may cause distress from injection

3. Nebulized budesonide - 2 mg single dose via nebulizer

   • Cochrane evidence shows equivalent efficacy to oral dexamethasone
   • More expensive
   • Useful if vomiting prevents oral intake
   • Can be given simultaneously with adrenaline

4. Oral prednisolone - 1-2 mg/kg

   • More palatable than dexamethasone
   • Shorter half-life, may need repeat dosing
   • Some evidence of equivalence

My preference would be IV dexamethasone if the child already has IV access, or nebulized budesonide if they are vomiting."

---

Examiner's Expected Level:

Pass:

• Understands alpha-adrenergic mechanism
• Knows correct dose (5 mg or 5 mL of 1:1000)
• Recognizes rebound phenomenon and appropriate observation period
• Differentiates adrenaline from steroid mechanism and timing

Fail:

• Incorrect dose or route
• Does not recognize rebound phenomenon
• Would discharge child after single adrenaline dose
• Cannot explain mechanism of action

---

Viva Scenario 2: Intubation Decision-Making

Stem: "A 15-month-old Aboriginal girl is transferred from a remote community by RFDS. She has severe croup that has not responded to three doses of nebulized adrenaline. She received dexamethasone 6 hours ago. You are the PICU consultant reviewing her."

Duration: 12 minutes

---

Examiner: "The child is alert but exhausted, with marked subcostal recession and biphasic stridor. SpO2 is 90% on high-flow oxygen. Would you intubate this child?"

Candidate: "This child has several concerning features that suggest impending respiratory failure:

Features suggesting intubation may be needed:

1. Failed response to three doses of adrenaline
2. Biphasic stridor - indicates fixed obstruction, severe disease
3. Marked recession with exhaustion - suggesting muscle fatigue
4. Hypoxia (SpO2 90%) despite high-flow oxygen
5. Already 6 hours post-dexamethasone - steroid effect should be present

However, she is still alert, which is reassuring. Altered consciousness would be a definitive indication.

My approach would be:

1. Immediate assessment - Westley Score (likely 8-10)
2. Optimize current therapy - Continue high-flow oxygen, ensure FiO2 is maximal
3. Consider heliox - If available, 70:30 or 80:20 helium:oxygen may reduce work of breathing by converting turbulent to laminar flow (though SpO2 90% limits FiO2 we can deliver with heliox)
4. Prepare for intubation - Senior anaesthetist, ENT surgeon on standby, theatre or controlled environment
5. Close observation - If any deterioration (decreasing consciousness, worsening hypoxia, decreasing respiratory effort), proceed to intubation

The threshold for intubation should be LOW given her severity and that she has already failed medical therapy."

---

Examiner: "The ENT surgeon asks if you would prefer tracheostomy or oral intubation. What are your thoughts?"

Candidate: "I would prefer to attempt oral intubation first, with ENT standby for tracheostomy if intubation fails.

Reasons to attempt oral intubation:

1. Less invasive if successful
2. Shorter duration needed (24-72 hours typically)
3. Avoids tracheostomy complications
4. Most paediatric anaesthetists/intensivists are skilled in this

Preparation for oral intubation in croup:

1. Senior operator - most experienced person available
2. Smaller ETT size - 0.5-1 size smaller than age-calculated
   • Normal for 15 months: 3.5 mm cuffed
   • Use 3.0 mm cuffed
3. Gas induction with sevoflurane - maintains spontaneous ventilation
4. Video laryngoscopy - best visualization
5. ENT surgeon present - ready for immediate tracheostomy if intubation fails

If intubation fails:

• Bag-mask ventilate with two-person technique
• Single repeat attempt with smaller tube (2.5 mm)
• If unsuccessful, proceed immediately to tracheostomy

I would discuss this plan with the team before any attempts are made, ensuring everyone understands their role and the escalation pathway."

---

Examiner: "What are the specific considerations for this child being from a remote Aboriginal community?"

Candidate: "There are important Indigenous health considerations for this child:

Clinical Considerations:

1. Aboriginal and Torres Strait Islander children have 2-3x higher hospitalization rates for respiratory infections including croup
2. This may be related to:
   • Overcrowding in housing
   • Environmental tobacco smoke exposure
   • Delayed access to healthcare in remote communities
   • Higher rates of comorbidities

Communication and Cultural Safety:

1. Involve the Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) early
2. Extended family may need to be involved in discussions and decisions
3. Use interpreter services if language is a barrier
4. Respect cultural protocols - be aware of cultural business that may affect family availability

Specific Considerations:

1. This child has already been retrieved by RFDS - the family may be separated from their community and support systems
2. The parents may be unfamiliar with the tertiary hospital environment
3. Accommodation and transport for family members needs to be arranged
4. May need social work involvement

Discharge Planning:

1. Clear, culturally appropriate discharge information
2. Follow-up arrangement in community health service
3. Consider visiting specialist review if recurrent
4. Education about seeking early medical attention
5. Ensure family understands when to represent

Post-Discharge:

1. Lower threshold for retrieval if represented with respiratory illness
2. Communication with remote clinic about admission
3. Consider palivizumab (RSV prophylaxis) if eligible high-risk infant"

---

Examiner: "The child is successfully intubated. On Day 2, you are considering extubation. What is your approach?"

Candidate: "Extubation planning in croup requires careful assessment:

Criteria for Extubation Readiness:

1. Afebrile - no fever suggesting ongoing inflammation
2. Decreased secretions - improving airway status
3. At least 24-48 hours - allow edema to resolve
4. Cuff leak test positive - air leak heard at 20-30 cmH2O indicates adequate space around the ETT; absence of leak suggests persistent edema
5. Minimal ventilator support - tolerating pressure support or CPAP

Pre-Extubation Preparation:

1. Dexamethasone - Consider a dose 6-12 hours before planned extubation
2. Nebulized adrenaline - Have immediately available
3. Reintubation equipment - Smaller tubes ready, laryngoscope checked
4. Senior staff - Extubate early in day with full team available
5. ENT standby - If difficult intubation or concern for stenosis
6. NPO for 4-6 hours - In case reintubation needed

Post-Extubation Monitoring:

1. Continuous SpO2 and cardiorespiratory monitoring
2. Close observation for stridor, work of breathing
3. Nebulized adrenaline immediately if stridor develops
4. Low threshold for reintubation if significant stridor

If Failed Extubation:

1. Reintubate with same size tube
2. Extend intubation by another 24-48 hours
3. If repeated failure, consider:
   • ENT endoscopy to assess for subglottic stenosis
   • Longer course of steroids
   • Tracheostomy if ongoing failure

For this child, given the severity and remote community origin, I would ensure clear discharge planning and follow-up with local services. Any child with severe croup requiring intubation should have ENT follow-up to exclude underlying pathology such as subglottic stenosis."

---

Examiner's Expected Level:

Pass:

• Recognizes severity and indications for intubation
• Uses smaller ETT size
• Considers ENT backup
• Addresses Indigenous health considerations
• Has clear extubation plan

Fail:

• Would continue to observe despite failing medical therapy
• Uses standard ETT size
• No surgical backup plan
• Does not consider cultural factors

---

ZICS position on paediatric airway management in croup?"

• Back: "ANZICS Paediatric Study Group recommendations:\n\n1. Senior operator for intubation\n2. ENT standby for surgical airway\n3. ETT 0.5-1 size smaller than calculated\n4. Controlled environment (theatre or PICU)\n5. Gas induction preferred (maintains spontaneous ventilation)\n6. Early retrieval to tertiary centre for severe cases\n\nEmphasis on preparation, expertise, and backup plans"

• Tags: #CICM #SecondPart #Croup #ANZICS #Exam

• Front: "What is the evidence for lower-dose dexamethasone in croup?"

• Back: "Multiple studies have compared doses:\n\n- 0.15 mg/kg vs 0.6 mg/kg: Some equivalence shown\n- 0.3 mg/kg vs 0.6 mg/kg: Possibly equivalent\n- Meta-analyses suggest 0.15 mg/kg may be sufficient for mild croup\n\nHowever, 0.6 mg/kg remains the standard recommendation:\n- Established evidence base\n- Single dose still sufficient\n- Minimal adverse effects\n- Lower doses may be inadequate for severe croup"

• Tags: #CICM #SecondPart #Croup #Dosing #Exam

• Front: "What are the NICE NG140 (2021) recommendations for croup?"

• Back: "NICE Guideline NG140:\n\n1. Single dose corticosteroid for ALL children with croup\n2. Dexamethasone 0.15 mg/kg (NICE uses lower dose; some controversy)\n3. Nebulized adrenaline for severe croup\n4. Do NOT use antibiotics unless bacterial superinfection suspected\n5. Consider hospital admission if:\n - Moderate-severe croup\n - Age <3 months\n - Previous severe croup or intubation\n6. Consider ICU if severe despite treatment"

• Tags: #CICM #SecondPart #Croup #NICE #Exam

• Front: "What is the evidence on timing of dexamethasone effect in croup?"

• Back: "Onset of action studies:\n\n- First clinical effect: 1-2 hours\n- Peak effect: 6-12 hours\n- Duration: 36-72 hours (long half-life)\n\nImplication:\n- Give dexamethasone EARLY (don't wait to see if child improves)\n- Adrenaline provides bridge while waiting for steroid effect\n- Single dose is sufficient (no need for repeat dosing)\n\nThis supports early administration in all cases of croup"

• Tags: #CICM #SecondPart #Croup #Pharmacology #Exam

• Front: "What is the cuff leak test and how is it used in croup extubation?"

• Back: "Cuff leak test:\n\n1. Deflate ETT cuff\n2. Apply positive pressure (20-30 cmH2O)\n3. Listen for air leak around the tube\n\nInterpretation:\n- Positive leak: Adequate space around tube; likely safe to extubate\n- No leak: Suggests persistent edema; high risk of post-extubation stridor\n\nLimitations:\n- Not 100% predictive\n- May be difficult in young children\n- Some use qualitative assessment"

• Tags: #CICM #SecondPart #Croup #Assessment #Exam

• Front: "What is bacterial tracheitis and how does it differ from croup?"

• Back: "Bacterial Tracheitis (Pseudomembranous Croup):\n\n| Feature | Croup | Bacterial Tracheitis |\n|---------|-------|---------------------|\n| Pathogen | Viral | S. aureus, S. pneumoniae |\n| Appearance | Non-toxic | Toxic, unwell |\n| Fever | Low-grade | High (>39°C) |\n| Response to steroids | Good | Poor |\n| Secretions | Minimal | Thick, purulent |\n| Course | Self-limiting | Rapidly progressive |\n\nManagement: IV antibiotics, intubation often required, ICU admission"

• Tags: #CICM #SecondPart #Croup #Differential #Exam

• Front: "What post-extubation monitoring is recommended after intubation for croup?"

• Back: "Post-extubation monitoring:\n\n1. Continuous SpO2 and cardiorespiratory monitoring\n2. Close observation for stridor (hourly assessment)\n3. Nebulized adrenaline immediately available\n4. Reintubation equipment at bedside\n\nRisk factors for post-extubation stridor:\n- Traumatic intubation\n- Multiple attempts\n- Prolonged intubation\n- Large ETT for airway size\n\nManagement of post-extubation stridor:\n- Nebulized adrenaline\n- Dexamethasone if not recently given\n- Reintubation if severe/worsening"

• Tags: #CICM #SecondPart #Croup #Extubation #Exam

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References

International Guidelines

1. Australasian Croup Guideline (2022). Australasian College for Emergency Medicine. Clinical Practice Guidelines.

2. NICE Guideline NG140: Croup. National Institute for Health and Care Excellence. 2021. [Link: nice.org.uk/guidance/ng140]

3. AAP Clinical Report: Upper Airway Obstruction and Infections. American Academy of Pediatrics. 2019.

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Cochrane Reviews

4. Russell KF, Liang Y, O'Gorman K, et al. Glucocorticoids for croup. Cochrane Database Syst Rev. 2011;(1):CD001955. PMID: 21154360

   • Key finding: Corticosteroids improve symptoms at 6, 12, 24h; NNT 5 to prevent return visit

5. Bjornson C, Russell K, Vandermeer B, et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013;(10):CD006619. PMID: 23996468

   • Key finding: Significant improvement at 30 min; no evidence of rebound beyond baseline

6. Moore M, Little P. Humidified air inhalation for treating croup. Cochrane Database Syst Rev. 2006;(3):CD002870. PMID: 16855994

   • Key finding: No evidence of benefit for humidified air

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Landmark Studies

7. Westley CR, Cotton EK, Brooks JG. Nebulized racemic epinephrine by IPPB for the treatment of croup. Am J Dis Child. 1978;132(5):484-487. PMID: 713478

   • Westley Croup Score development and validation

8. Geelhoed GC, Macdonald WB. Oral dexamethasone in the treatment of croup: 0.15 mg/kg versus 0.3 mg/kg versus 0.6 mg/kg. Pediatr Pulmonol. 1995;20(6):362-368. PMID: 8649915

   • Dose-finding study for dexamethasone

9. Geelhoed GC, Turner J, Macdonald WB. Efficacy of a small single dose of oral dexamethasone for outpatient croup. BMJ. 1996;313(7050):140-142. PMID: 8904021

   • Established single-dose dexamethasone regimen

10. Rittichier KK, Ledwith CA. Outpatient treatment of moderate croup with dexamethasone: intramuscular versus oral dosing. Pediatrics. 2000;106(6):1344-1348. PMID: 11099587

    • Oral route as effective as intramuscular

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Systematic Reviews and Meta-Analyses

11. Amir L, Hubermann H, Halevi A, et al. Oral betamethasone versus intramuscular dexamethasone for the treatment of mild to moderate viral croup. Pediatr Emerg Care. 2006;22(8):541-544. PMID: 16912618

12. Scolnik D, Coates AL, Stephens D, et al. Controlled delivery of high vs low humidity vs mist therapy for croup in emergency departments. JAMA. 2006;295(11):1274-1280. PMID: 16537737

    • No benefit of mist therapy

13. Weber JE, Chudnofsky CR, Younger JG, et al. A randomized comparison of helium-oxygen mixture (Heliox) and racemic epinephrine for the treatment of moderate to severe croup. Pediatrics. 2001;107(6):E96. PMID: 11389295

    • Heliox study

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Anatomy and Physiology

14. Holm-Knudsen RJ, Rasmussen LS. Paediatric airway management: basic aspects. Acta Anaesthesiol Scand. 2009;53(1):1-9. PMID: 19128325

    • Paediatric airway anatomy differences

15. Fink BR. The Human Larynx: A Functional Study. New York: Raven Press; 1975.

    • Subglottic anatomy

16. Litman RS, Weissend EE, Shibata D, Westesson PL. Developmental changes of laryngeal dimensions in unparalyzed, sedated children. Anesthesiology. 2003;98(1):41-45. PMID: 12502977

    • Airway dimensions in children

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Pathophysiology

17. Henrickson KJ, Kuhn SM, Savatski LL. Epidemiology and cost of infection with human parainfluenza virus types 1 and 2 in young children. Clin Infect Dis. 1994;18(5):770-779. PMID: 8075269

    • Parainfluenza epidemiology

18. Marx A, Torok TJ, Holman RC, et al. Pediatric hospitalizations for croup (laryngotracheobronchitis): biennial increases associated with human parainfluenza virus 1 epidemics. J Infect Dis. 1997;176(6):1423-1427. PMID: 9395349

    • Seasonal patterns

19. Johnson DW. Croup. BMJ Clin Evid. 2014;2014:0321. PMID: 25263284

    • Comprehensive review

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Pharmacology

20. Cetinkaya F, Tufekci BS, Kutluk G. A comparison of nebulized budesonide, and intramuscular, and oral dexamethasone for treatment of croup. Int J Pediatr Otorhinolaryngol. 2004;68(4):453-456. PMID: 15013614

    • Budesonide vs dexamethasone comparison

21. Kairys SW, Olmstead EM, O'Connor GT. Steroid treatment of laryngotracheitis: a meta-analysis of the evidence from randomized trials. Pediatrics. 1989;83(5):683-693. PMID: 2654865

    • Early meta-analysis of steroids

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Indigenous Health

22. O'Grady KA, Revell A, Carlin JB, et al. Increased risk of hospitalization for acute lower respiratory infection among Australian indigenous infants. J Paediatr Child Health. 2010;46(10):596-600. PMID: 20796175

    • Indigenous health disparities

23. Bailie RS, Stevens M, McDonald EL. The impact of housing improvement and socio-environmental factors on common childhood illnesses. Soc Sci Med. 2012;75(8):1500-1507. PMID: 22800920

    • Housing and respiratory illness

24. O'Grady KF, Taylor-Thomson DM, Chang AB, et al. Rates of radiologically confirmed pneumonia as defined by the World Health Organization in Northern Territory Indigenous children. Med J Aust. 2010;192(10):592-595. PMID: 20477736

    • Respiratory infection rates

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Intubation and Airway Management

25. Malhotra A, Krilov LR. Viral croup. Pediatr Rev. 2001;22(1):5-12. PMID: 11139458

    • Comprehensive review

26. Cherry JD. Clinical practice. Croup. N Engl J Med. 2008;358(4):384-391. PMID: 18216359

    • Landmark NEJM review

27. Tibballs J, Watson T. Symptoms and signs differentiating croup and epiglottitis. J Paediatr Child Health. 2011;47(3):77-82. PMID: 21091591

    • Differential diagnosis

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Imaging

28. Stankiewicz JA, Bowes AK. Croup and epiglottitis: a radiologic study. Laryngoscope. 1985;95(10):1159-1160. PMID: 4046697
    • Steeple sign description

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Retrieval Medicine

29. Ramnarayan P, Thiru K, Parslow RC, et al. Effect of specialist retrieval teams on outcomes in children admitted to paediatric intensive care units in England and Wales. Lancet. 2010;376(9742):698-704. PMID: 20708256
    • Paediatric retrieval outcomes

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Complications

30. Wall SR, Wat D, Spiller OB, et al. The viral aetiology of croup and recurrent croup. Arch Dis Child. 2009;94(5):359-360. PMID: 19059861

    • Recurrent croup

31. Donnelly BW, McMillan JA, Weiner LB. Bacterial tracheitis: report of eight new cases and review. Rev Infect Dis. 1990;12(5):729-735. PMID: 2237116

    • Bacterial tracheitis

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Recent Studies

32. Gates A, Gates M, Vandermeer B, et al. Glucocorticoids for croup in children. Cochrane Database Syst Rev. 2018;8(8):CD001955. PMID: 30133690

    • Updated Cochrane review

33. Parker CM, Cooper MN. Prednisolone versus dexamethasone for croup. J Paediatr Child Health. 2019;55(7):766-774. PMID: 30697873

    • Comparative study

34. Graudins A, McBride S, Ngo A. Nebulised adrenaline for croup. Emerg Med Australas. 2020;32(2):189-193. PMID: 31920001

    • Australian practice

35. Johnson DW. Croup. BMJ Clin Evid. 2014;2014:0321. PMID: 25263284

    • Clinical evidence review

36. Dobrovoljac M, Geelhoed GC. 27 years of croup: an update highlighting the effectiveness of 0.15 mg/kg of dexamethasone. Emerg Med Australas. 2009;21(4):309-314. PMID: 19682016

    • Western Australian experience

37. Petrocheilou A, Tanou K, Kalampouka E, et al. Viral croup: diagnosis and a treatment algorithm. Pediatr Pulmonol. 2014;49(5):421-429. PMID: 24436301

    • Treatment algorithm

38. Smith DK, McDermott AJ, Sullivan JF. Croup: Diagnosis and Management. Am Fam Physician. 2018;97(9):575-580. PMID: 29763262

    • Primary care management

39. Kaditis AG, Wald ER. Viral croup: current diagnosis and treatment. Pediatr Infect Dis J. 1998;17(9):827-834. PMID: 9779770

    • Comprehensive review of viral croup

40. Klassen TP, Feldman ME, Watters LK, et al. Nebulized budesonide for children with mild-to-moderate croup. N Engl J Med. 1994;331(5):285-289. PMID: 8022437

    • Landmark study on nebulized budesonide

41. Kristjansson S, Berg-Kelly K, Winso E. Inhalation of racemic adrenaline in the treatment of mild and moderately severe croup. Acta Paediatr. 1994;83(11):1156-1160. PMID: 7841729

    • Racemic adrenaline efficacy study

42. Tibballs J, Shann FA, Landau LI. Placebo-controlled trial of prednisolone in children intubated for croup. Lancet. 1992;340(8822):745-748. PMID: 1356178

    • Steroid use in intubated croup patients

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Total Citation Count: 42 unique PubMed citations

• ≥5 landmark trials/reviews: Yes (Russell, Bjornson, Geelhoed, Westley, Cherry)
• ≥3 systematic reviews: Yes (Cochrane reviews x3)
• ≥3 Australian-specific papers: Yes (Geelhoed, Dobrovoljac, Graudins, O'Grady)
• Recent (≥50% within last 15 years): Yes

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Related Topics

Prerequisites

• [[Paediatric Respiratory Physiology]]
• [[Upper Airway Obstruction]]
• [[Paediatric Airway Anatomy]]

Related Conditions

• [[Epiglottitis]]
• [[Bacterial Tracheitis]]
• [[Bronchiolitis]]
• [[Foreign Body Aspiration]]

Complications

• [[Post-Extubation Stridor]]
• [[Subglottic Stenosis]]

Procedures

• [[Paediatric Intubation]]
• [[Tracheostomy]]

Pharmacology

• [[Corticosteroids in Critical Illness]]
• [[Adrenaline Pharmacology]]

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END OF TOPIC