🔑 Key Learning

  • Bronchiolitis is the most common lower respiratory tract infection in infants, often caused by RSV
  • Viral-induced wheeze presents similarly to asthma but only occurs during viral illness and typically resolves by age 6
  • Pertussis (whooping cough) has a prolonged course and a distinct whooping sound — it is notifiable. Mx: Macrolide antibiotics. 
  • Croup causes a characteristic barking cough and stridor, treated with steroids (e.g. PO dexamethaszone stat dose) (± adrenaline)
  • Epiglottitis is now rare due to Hib vaccination but remains a paediatric emergency

🌫️ Acute Bronchiolitis

🦠 Cause

  • Most common: RSV
  • Others: adenovirus, parainfluenza, mycoplasma

📊 Incidence

  • Age: <1 year (especially <6 months)
  • Season: Winter

👀 Clinical Features

  • Coryzal prodrome → cough, fever (usually <39°C)
  • Respiratory distress: nasal flaring, grunting, intercostal recession, tracheal tug
  • Bilateral wheeze and crackles
  • Apnoeas may occur
  • Reduced feeding due to increased work of breathing

💊 Management

  • Supportive care:
    • O₂ if SpO₂ < 92%
    • NG feed/IV fluids if feeding compromised
    • Ventilatory support if needed
  • Prevention: Palivizumab for high-risk infants (e.g. prematurity, congenital heart disease)

🌬️ Viral-Induced Wheeze (VIW)

🧬 Pathophysiology

  • Inflammation, oedema, and smooth muscle constriction in small airways
  • Wheeze not seen in older children due to larger airways

📊 Epidemiology

  • Age: 6 months to 5 years
  • Typically resolves by age 6

👀 Clinical Features

  • Only during viral illness (differentiates from asthma) - no 'interval' symptoms
  • SOB, wheeze, increased work of breathing
  • No atopy/family history

💊 Management

  • SABA (e.g. salbutamol) during symptomatic episodes

😮‍💨 Whooping Cough (Pertussis)

🦠 Cause

  • Bordetella pertussis

📊 Incidence

  • Peaks in infants and >14 years

👀 Clinical Features

3 phases:

  1. Catarrhal (1–2 wks): Mild fever, cough, coryza
  2. Paroxysmal (2–6 wks):
    • Severe coughing fits, vomiting, fainting
    • Inspiratory whoop (due to closed glottis)
  3. Convalescent (2–4 wks): Gradual resolution
  • Symptoms may persist for months ("100-day cough")

🧪 Diagnosis

  • Nasal PCR/culture
  • Oral fluid IgG if >2 wks of symptoms (esp. <16 yrs)

💊 Management

  • Clarithromycin (or erythromycin in pregnancy)
    • Co-trimoxazole if macrolides contraindicated
  • Notifiable disease
    • Isolate until 48 hours after antibiotic treatment, or for 14 days from the onset of coughing if not treated.
    • Consider prophylactic ABx for contacts
    • Notify Public Health England

🐶 Croup (Acute Laryngotracheobronchitis)

🦠 Cause

  • Parainfluenza virus
  • Also RSV

📊 Incidence

  • Age: 6 months to 6 years (most commonly 6 months–3 years)

👀 Clinical Features

  • Coryzal prodrome (24–72 hrs)
  • Sudden onset barking cough (seal-like), worse at night
  • Hoarse voice, stridor, respiratory distress

🧪 Classification

  • Mild: Barking cough only
  • Moderate: Stridor + sternal recession at rest
  • Severe: Stridor + intercostal recession + agitation/lethargy

💊 Management

  • All cases: Oral dexamethasone 0.15 mg/kg (or IM/inhaled alternative)
  • Moderate/severe: Admit ± nebulised adrenaline

🔥 Epiglottitis

🦠 Cause

  • Historically Hib (now rare)
  • Now usually Streptococcus pneumoniae / pyogenes

📊 Incidence

  • Age: 2–7 years

👀 Clinical Features

  • Abrupt onset sore throat, odynophagia, fever
  • Continuous stridor
  • Drooling, muffled voice
  • Tripod position
  • Minimal tachypnoea but evident distress

💊 Management

  • Do not examine throat (risk of airway compromise)
  • May need intubation
  • IV cefotaxime or cefuroxime

📝 Exam Clues & Clinchers

  • Infant <6 months, winter, wheeze + crackles → bronchiolitis
  • Age <5 yrs, wheeze only during illness → viral wheeze
  • Seal-like cough, stridor, night-time worsening → croup
    • Management: PO dexamethasone (admit if stridor)
  • Cough with inspiratory whoop, vomiting after fits → pertussis
    • Management: Clarithromycin
  • Sore throat + drooling + tripod position → epiglottitis (emergency)

🔗 Useful Links and References

NICE. Bronchiolitis in children: diagnosis and management [NG9] [2015]. Available at URL: https://www.nice.org.uk/guidance/ng9/chapter/1-Recommendations

NICE CKS. Croup [May 2022]. Available at URL: https://cks.nice.org.uk/topics/croup/