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Croup Severity Score (Westley)の包括的な教育ガイドを準備中です。ステップバイステップの解説、数式、実例、専門家のヒントをお届けしますので、もうしばらくお待ちください。
The Westley Croup Score is a validated clinical scoring system used to assess the severity of croup (laryngotracheobronchitis) in children and guide treatment decisions. Croup is a common upper respiratory tract illness caused predominantly by parainfluenza virus types 1 and 2, characterised by the distinctive barking or seal-like cough, stridor (harsh inspiratory noise from subglottic airway narrowing), and varying degrees of respiratory distress. It affects predominantly children aged 6 months to 3 years and has a peak incidence in autumn. The Westley score, developed by Christopher Westley and colleagues in 1978, quantifies severity across five clinical domains: stridor (0-2), retractions (0-3), air entry (0-2), cyanosis (0-4), and level of consciousness (0-5), for a possible total of 0-17. Mild croup (score ≤2) requires only oral or intramuscular dexamethasone and parental education. Moderate croup (score 3-7) warrants dexamethasone plus nebulised adrenaline (epinephrine) to reduce airway oedema acutely. Severe croup (score ≥8) requires emergency management including possible intubation and ICU admission. Dexamethasone is the corticosteroid of choice — a single oral dose of 0.15 mg/kg (range 0.15-0.6 mg/kg) is highly effective, has a prolonged duration of action (approximately 24 hours due to its 36-54 hour half-life), and has revolutionised croup management by dramatically reducing the need for hospitalisation and intubation. Nebulised adrenaline (epinephrine 0.5 mL/kg of 1:1000, max 5 mL) provides rapid but temporary (approximately 2-hour) relief of stridor through vasoconstriction, warranting 2-4 hours of observation after administration to monitor for rebound.
Westley Score = Stridor(0-2) + Retractions(0-3) + Air Entry(0-2) + Cyanosis(0-4) + Level of Consciousness(0-5); Mild ≤2; Moderate 3-7; Severe ≥8; Treatment: Mild=oral dexamethasone 0.15mg/kg; Moderate=dexamethasone+nebulised adrenaline; Severe=ICU + possible intubation
- 1Assess stridor: 0 = none; 1 = stridor only on agitation or crying; 2 = stridor at rest. Inspiratory stridor at rest indicates significant subglottic narrowing.
- 2Assess retractions: 0 = none; 1 = mild (subtle suprasternal and intercostal); 2 = moderate (obvious suprasternal, sternal, and intercostal); 3 = severe (suprasternal, sternal, intercostal, and subcostal).
- 3Assess air entry by auscultation: 0 = normal equal bilateral breath sounds; 1 = mildly decreased air entry; 2 = markedly decreased air entry (quiet chest indicating critical obstruction).
- 4Assess cyanosis: 0 = none; 4 = cyanosis at rest (this is scored 0 or 4; intermediate values are not used in the original scale). Cyanosis indicates critical hypoxia.
- 5Assess level of consciousness: 0 = normal; 5 = altered consciousness/obtunded (indicating severe hypoxia or hypercapnia). Reduced consciousness is the most ominous sign.
- 6Sum all components for the total Westley score. Classify severity: ≤2 = mild; 3-7 = moderate; ≥8 = severe. A score of 12 or above represents very severe, impending respiratory failure.
- 7Apply treatment based on severity: mild — single oral dexamethasone 0.15 mg/kg, may discharge with safety net advice; moderate — dexamethasone plus nebulised adrenaline, observe 2-4 hours post-adrenaline for rebound, consider admission; severe — emergency treatment, summon experienced senior clinician, prepare for intubation with smaller ETT size, activate ICU.
Oral dexamethasone 0.15 mg/kg single dose; advise parents on warning signs; discharge
A score of 1 represents mild croup with stridor only on agitation. A single dose of oral dexamethasone reduces symptom duration and severity. The child can be safely discharged if social circumstances are appropriate and parents understand when to return.
Dexamethasone 0.15 mg/kg PO STAT + nebulised adrenaline 0.5mL/kg 1:1000 in 3mL saline; observe 4 hours
Moderate croup with resting stridor and retractions requires both corticosteroid and adrenaline. The child must be observed for at least 2-4 hours after adrenaline for rebound stridor before considering discharge.
Adrenaline nebuliser immediately; dexamethasone if not already given; PICU team; prepare for intubation
A score of 11 indicates severe croup with impending respiratory failure. Nebulised adrenaline provides temporary relief while definitive management (including possible intubation) is arranged. An ETT 0.5-1 mm smaller than calculated should be used due to subglottic narrowing.
Adrenaline action lasts only 2 hours; do not discharge until 4 hours post-adrenaline and stable
Rebound stridor occurs when the vasoconstriction from adrenaline wears off. This is why observation for 4 hours post-adrenaline is mandatory. A second nebulised adrenaline dose can be given; admission is usually warranted.
Paediatric emergency department triage and treatment decision-making for children presenting with barking cough and stridor.. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Determining admission versus discharge: Westley score guides the clinician on whether dexamethasone alone permits safe discharge or nebulised adrenaline and admission are required.. Industry practitioners rely on this calculation to benchmark performance, compare alternatives, and ensure compliance with established standards and regulatory requirements
Clinical audit: tracking Westley scores at presentation and post-treatment in paediatric emergency audit programmes.. Academic researchers and students use this computation to validate theoretical models, complete coursework assignments, and develop deeper understanding of the underlying mathematical principles
Simulation training for APLS and PALS courses: croup management is a core paediatric emergency scenario using the Westley framework.. Financial analysts and planners incorporate this calculation into their workflow to produce accurate forecasts, evaluate risk scenarios, and present data-driven recommendations to stakeholders
Research: Westley score is the primary outcome measure in clinical trials of croup treatments, including dexamethasone dosing studies and novel anti-inflammatory interventions.. This application is commonly used by professionals who need precise quantitative analysis to support decision-making, budgeting, and strategic planning in their respective fields
Spasmodic Croup
Spasmodic croup is a recurrent non-infectious variant characterised by sudden onset of barking cough and stridor at night, often without fever or viral prodrome, and typically resolving spontaneously by morning. It is thought to be allergic or psychogenic in origin. It responds to dexamethasone and supportive care but may recur. Distinguishing it from infectious croup is important as workup for other causes of recurrent stridor (vascular ring, laryngeal papillomatosis) may be warranted.
Bacterial Tracheitis
Bacterial tracheitis (Staphylococcus aureus, including MRSA) mimics severe croup but does not respond to dexamethasone or adrenaline. Children appear toxic, often with high fever and rapid deterioration. Diagnosis is confirmed by direct laryngoscopy revealing purulent pseudomembranes in the trachea. Treatment requires immediate airway protection, IV antibiotics (flucloxacillin ± clindamycin), and ICU admission.
Foreign Body Aspiration
Foreign body aspiration can mimic croup with sudden onset stridor and barking cough. Key distinguishing features: sudden onset without prodrome, failure to respond to standard croup treatment, unilateral wheeze or reduced air entry, and a history of choking episode. Chest X-ray may show hyperinflation or atelectasis. Rigid bronchoscopy is diagnostic and therapeutic.
Recurrent Croup (>3 episodes)
Children with more than 3 episodes of croup should be evaluated for structural airway abnormalities: subglottic stenosis (congenital or acquired), laryngeal papillomatosis (HPV), vascular rings compressing the trachea, or subglottic haemangioma. Referral to paediatric ENT for direct laryngoscopy and airway evaluation is appropriate.
| Parameter | 0 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|
| Stridor | None | Agitation only | At rest | – | – | – |
| Retractions | None | Mild | Moderate | Severe | – | – |
| Air Entry | Normal | Decreased | Markedly decreased | – | – | – |
| Cyanosis | None | – | – | – | At rest (=4) | – |
| Consciousness | Normal | – | – | – | – | Obtunded (=5) |
What is the difference between croup and epiglottitis?
Croup (laryngotracheobronchitis) causes gradual-onset barking cough, stridor, and low-grade fever in children under 3, typically with a viral prodrome. Epiglottitis causes rapidly progressive high fever, drooling, toxic appearance, and a muffled voice (not barking cough) in older children and is a surgical emergency. Epiglottitis is now rare due to Hib vaccination. Never examine the throat or attempt IV access in a suspected epiglottitis patient without anaesthesia support immediately available.
What is the mechanism of dexamethasone in croup?
Dexamethasone reduces laryngeal and subglottic mucosal oedema through its anti-inflammatory effects. It decreases vascular permeability and suppresses the inflammatory cytokine cascade triggered by viral infection. A single oral dose of 0.15 mg/kg is effective within 6 hours and provides clinical benefit lasting up to 24-48 hours due to dexamethasone's long half-life.
Why is nebulised adrenaline only temporary?
Nebulised adrenaline (epinephrine) acts as an alpha-adrenergic agonist, causing vasoconstriction of the subglottic mucosal vessels, which reduces oedema and stridor within minutes. However, the vasoconstriction wears off in approximately 1.5-2 hours, and the underlying oedema may return (rebound effect). This is why 2-4 hours of post-adrenaline observation is mandatory. This matters because accurate croup westley score calculations directly affect decision-making in professional and personal contexts.
Can croup be treated with budesonide?
Yes. Nebulised budesonide (2 mg) is as effective as oral dexamethasone for moderate croup and is useful when the child is unable to take oral medication due to vomiting. However, oral or IM dexamethasone is preferred when possible due to ease of administration and equivalent efficacy. This is an important consideration when working with croup westley score calculations in practical applications.
Is humidified air or steam helpful for croup?
Despite being a long-standing traditional remedy, humidified air and steam therapy have no proven benefit in randomised controlled trials and may carry risks (scalding, worsening agitation). Current evidence-based guidelines do not recommend steam inhalation for croup; dexamethasone is the only pharmacological treatment with strong evidence. This is an important consideration when working with croup westley score calculations in practical applications.
What ETT size should be used for intubating a child with severe croup?
Due to subglottic narrowing, the ETT should be 0.5-1 mm smaller than calculated for age. An experienced paediatric anaesthetist or intensivist should perform or supervise intubation. Anticipate difficulty passing the tube through the narrowed subglottis; have a variety of tube sizes available. Early tracheostomy may be required if intubation is impossible.
When should a child with croup be admitted to hospital?
Admission is indicated for: Westley score ≥3 that does not improve with treatment; requirement for nebulised adrenaline (observe 4 hours minimum); recurrent presentation within 24 hours; concerns about parental ability to monitor or access emergency care; or clinical concerns about the diagnosis (consider foreign body, epiglottitis, bacterial tracheitis). This applies across multiple contexts where croup westley score values need to be determined with precision.
What should parents be told when discharging a child with mild croup?
Parents should be advised to return immediately if: stridor is present at rest; breathing becomes laboured or fast; the child becomes unusually pale, drowsy, or unable to swallow; cyanosis develops; or if the child's condition fails to improve within 24-48 hours. The barking cough typically worsens at night and may improve slightly in the morning — this pattern is characteristic and reassuring.
プロのヒント
A calm environment significantly reduces croup severity — agitation and crying worsen the negative intrathoracic pressure that perpetuates stridor. Keep the child with a parent, avoid distressing procedures, and if possible administer dexamethasone orally first before attempting IV access. A settled child may improve dramatically even before adrenaline is considered.
ご存知でしたか？
The barking cough characteristic of croup earned it the name 'croup' from the Anglo-Saxon word 'roup', meaning to cry out in a hoarse voice. In 18th and 19th century England, croup (then including diphtheria) was one of the most feared childhood illnesses, causing numerous epidemics. The introduction of the diphtheria vaccine dramatically reduced the incidence of membranous (diphtheritic) croup, while viral laryngotracheobronchitis remains common today but is usually self-limiting and well-managed with modern treatments.
参考文献
- ›Westley CR et al. Nebulized racemic epinephrine by IPPB for the treatment of croup. Am J Dis Child 1978.
- ›Russell KF et al. Glucocorticoids for croup. Cochrane Database Syst Rev 2011.
- ›Bjornson CL, Johnson DW. Croup in children. BMJ 2008.
- ›NICE Guideline NG143 — Fever in under 5s. 2019 (croup section).