Bronchiolitis — SAQ

Stem

A candidate is asked to manage a classic presentation of Bronchiolitis in an exam setting. Use precise definitions, scores, doses, and decision thresholds.

Core knowledge (model answer backbone)

Bronchiolitis is an acute viral lower respiratory tract infection of the small airways (bronchioles) in infants, typically under 2 years (peak 2 to 6 months), caused mainly by respiratory syncytial virus (RSV, 70 to 80 percent). Presentation: coryzal prodrome for 1 to 3 days, then worsening cough, wheeze, tachypnoea, and respiratory distress (nasal flaring, recession, grunting, head bobbing), with bilateral crackles and wheeze on auscultation. Most cases are mild and self-limiting. Treatment is supportive: oxygen if SpO2 persistently under 92 percent, nasal suctioning, and hydration (oral, NG, or IV). Bronchodilators, corticosteroids, antibiotics, chest physiotherapy, and routine imaging are NOT recommended. Severe disease may need high-flow nasal cannula, CPAP, or mechanical ventilation. Prevention: palivizumab 15 mg/kg monthly IM for high-risk infants during RSV season; nirsevimab (single long-acting dose) for all infants in regions where it is funded.

Red flags

• Severe respiratory distress with marked recession, grunting, nasal flaring, head bobbing, cyanosis, or exhaustion - urgent assessment, oxygen, escalate respiratory support (HFNC, CPAP, intubation)
• Apnoea in an infant under 3 months (especially ex-preterm) - may be the presenting feature of bronchiolitis; admit, continuous SpO2 and apnoea monitoring, caffeine, prepare for respiratory support
• SpO2 persistently under 92 percent in air despite supplemental oxygen - escalate from standard oxygen to HFNC or CPAP; consider PICU
• Inability to feed or maintain hydration - nasogastric or IV fluids; under 3 months with poor feeding should be admitted

High-yield structure examiners expect

Cover: Overview & Definition, Classification, Epidemiology & Risk Factors, Pathophysiology, Clinical Presentation, Differential Diagnosis.

Key doses / thresholds (from topic teaching)

• palivizumab 15 mg/kg monthly IM** for high-risk infants,
• The AAP 2014 guideline and the Cochrane reviews conver
• sweat chloride over 60 mmol/L", "CF team, chest physiotherapy (here
• caffeine citrate 20 mg/kg loading dose**, and escalate early t
• paracetamol 15 mg/kg q4-6h or ibuprofen 10 mg/kg q6-8h if
• caffeine citrate 20 mg/kg**

Questions

a) Define the condition and give the most important classification or severity framework used in exams. (3 marks)

• Clear one-line definition matching standard teaching.
• Named classification / stages / types with discriminating features.
• One sentence on why classification changes management.

b) Outline pathophysiology in a mechanism chain that explains the main clinical features. (3 marks)

• Initiating insult → intermediate pathway → end-organ effect.
• Link at least two symptoms/signs to mechanism.
• Mention one complication pathway (e.g. shock, perforation, herniation, arrhythmia).

c) List discriminating clinical features and bedside assessment. (3 marks)

• Classic presentation plus one atypical group (elderly, pregnancy, child, immunocompromised).
• Named signs/manoeuvres if relevant.
• What must never be missed on exam/bedside (pregnancy test, airway, glucose, etc.).

d) Investigations with thresholds and one named score if applicable. (3 marks)

• First-line tests and what positive findings mean.
• Gold-standard or definitive investigation when needed.
• Score components reproduced exactly if a named score is standard for this topic.

e) Immediate resuscitation and definitive management with doses where standard. (3 marks)

• ABC / time-critical steps first.
• First-line drug(s) with agent + dose + route (or procedure steps).
• Escalation triggers (theatre, ICU, thrombolysis window, antidote, etc.).
• Disposition and safety-netting.

Marking tips

Full marks require specificity (numbers, names, doses) not generic "give antibiotics/fluids." Regional practice (ICMR / NICE / AHA) may be cited as alternative where relevant.