Croup

Related Subjects: | Acute Epiglottitis | Croup | Acute Tracheitis | Stridor | Acute Bacterial Meningitis (Children)

👶 About

• Croup = acute laryngotracheobronchitis causing inflammation & narrowing of the subglottic airway.
• Affects mainly children 6 months–3 years (peak 18 months).
• Seasonal → more common in autumn/winter.
• Usually self-limiting but may progress to severe airway obstruction.

🦠 Aetiology

• Most often viral: parainfluenza (75%), also RSV, adenovirus, influenza, rhinovirus.
• Spread by respiratory droplets, incubation ~2–4 days.

🦠 Microbiology of Croup

• 👑 Parainfluenza viruses → cause ~75% of croup cases.
  • Types 1 & 2 = classic “croup viruses” (autumn peaks, epidemics every 2 years).
  • Type 3 can cause more severe disease in infants.
• 🌡️ Other viral causes:
  • Respiratory Syncytial Virus (RSV)
  • Adenovirus
  • Rhinovirus
  • Influenza A & B (tend to cause more severe croup, especially in younger children)
  • Enteroviruses (rare)
• 🧬 Pathophysiology:
  • Viruses infect the respiratory epithelium, causing local inflammation.
  • Greatest narrowing occurs in the subglottic region (smallest part of paediatric airway).
  • Even mild oedema → disproportionately large increase in airway resistance (Poiseuille’s law → resistance ∝ radius⁴).
• 🧪 Superinfection:
  • Rare in croup itself, but bacterial tracheitis (often due to Staph aureus, Strep pneumoniae, or Haemophilus influenzae) can complicate or mimic severe croup.

💡 Clinical pearl: Croup = viral (no antibiotics). If the child fails to improve or deteriorates rapidly → think of bacterial tracheitis or epiglottitis.

🩺 Clinical Presentation

• Child often has preceding coryza/URTI symptoms.
• Key features:
  • 🎵 Harsh, inspiratory stridor
  • 🐶 Barking “seal-like” cough
  • 🔊 Hoarseness of voice
  • 😰 Varying degrees of respiratory distress (recession, tachypnoea)
  • 🌡️ Low-grade fever
• Assessment tips:
  • 👩‍👦 Keep child calm, let them sit on caregiver’s lap.
  • 🛑 Avoid throat examination & do not force supine position.
  • 💨 If hypoxic → gentle facemask O₂.

📉 Assessing Severity

• 🙂 Mild: Barking cough only, no stridor at rest, normal mental state.
• 😟 Moderate: Stridor & chest recession at rest, but no agitation or lethargy.
• 😫 Severe: Stridor at rest, marked recession, agitation or lethargy.
• 🚨 Impending Respiratory Failure: Silent chest/stridor, severe recession, asynchronous chest wall movement, tachycardia, cyanosis, ↓ GCS. RR >70/min = very severe distress.

🔍 Differential Diagnosis (don’t miss!)

• Epiglottitis: ⏱️ Sudden onset, high fever >38.5°C, drooling, quiet stridor, minimal cough.
• Diphtheria: 😷 Grey pseudomembrane, bull neck, myocarditis (rare in immunised populations).
• Bacterial Tracheitis: 🦠 Thick secretions, high fever, toxic child, poor response to steroids.
• Foreign body aspiration: ⚠️ Sudden stridor, unilateral signs.
• Anaphylaxis: 🥜 Urticaria, angioedema, wheeze, stridor.

📊 Comparison of Croup, Epiglottitis, and Bacterial Tracheitis

🛠️ Management

• 🏡 Home (mild cases):
  • Single dose dexamethasone 0.15 mg/kg PO (max 10 mg).
  • Reassure parents: usually resolves within 48h.
  • Safety net: 🚨 return if stridor at rest, worsening recession, cyanosis, ↓ responsiveness.
• 👩‍⚕️ General Care:
  • Paracetamol/ibuprofen for fever.
  • Encourage fluids, breastfeeding.
  • Check overnight for deterioration.
• 🏥 Hospital Admission:
  • Indicated if moderate/severe distress, stridor at rest, comorbidities, or social concerns.
  • Dexamethasone 0.15–0.6 mg/kg PO/IM/IV (or nebulised budesonide 2 mg if not tolerating PO).
  • Nebulised adrenaline 1:1000, 5 mL via oxygen-driven nebuliser → review after 15–30 mins. May repeat.
  • Monitor sats, admit under paediatrics ± PICU backup if severe.
• 🚨 Impending respiratory failure: Senior paediatric + anaesthetic involvement, prepare for intubation in theatre.

📝 Exam / OSCE Pearls

• Buzzwords: “seal-like cough + stridor”.
• Croup severity → Westley score (not often used in UK exams, but conceptually helpful).
• Always contrast with epiglottitis (sudden onset, drooling, toxic).
• Dexamethasone is the drug of choice, even for mild cases.
• Adrenaline neb = rescue for severe obstruction.

📚 References

• NICE CKS: Croup
• RCPCH PEM Curriculum