Acute Bronchiolitis – Complete PLAB 2 Guide

Ann Augustin
Apr 26
2 min read

What is Bronchiolitis?

Acute bronchiolitis is a viral infection of the small airways (bronchioles), most commonly caused by Respiratory Syncytial Virus. It leads to inflammation, swelling, and mucus plugging, making breathing difficult in infants.

👶 Age Group Affected

< 2 years old
Peak: 2–6 months
More severe in:
- Infants <3 months
- Premature babies
- Underlying heart/lung disease

👉 Most common cause of wheeze and shortness of breath in infants (<1 year)

Disease Progression (Classic Timeline)

Day 1–3 (URTI phase)
- Runny nose, mild fever, cough
Day 3–5 (Peak severity) 🚨
- Fast breathing, wheeze, chest recession
- Feeding difficulty
Severe phase (some infants)
- Apnoea, hypoxia → may need oxygen/support
Recovery (Day 5–10)
- Gradual improvement
Residual cough
- May last 2–3 weeks

👉 Key exam point: Peaks at day 3–5, resolves in 1–2 weeks

Does it Recur?

Reinfection can happen (immunity not complete)
But:
- True recurrent bronchiolitis → uncommon
- Recurrent wheeze → common (post-viral / asthma-like)

Hospital Management (Moderate–Severe Cases)

Supportive care is the cornerstone:

Oxygen (if SpO₂ <92%)
Fluids (oral/NG/IV)
Minimal handling
Nasal suction

Not routinely used:

Antibiotics
Bronchodilators (salbutamol)
Steroids
Nebulised adrenaline

Home Management (Mild Cases)

Small, frequent feeds
Nasal saline + suction
Paracetamol for fever
Keep baby slightly upright

❌ Avoid:

Cough syrups
Inhalers/nebulisers (not effective)

Nebulisers & Spacers – Are They Used?

👉 No, not routinely

Bronchiolitis is not an asthma-type disease
Caused by mucus + inflammation, not bronchospasm

👉 Trial may be considered in select cases (older infant, atopy), but:

Stop if no improvement

When to Admit

Poor feeding / dehydration
Severe respiratory distress
Apnoea
Low oxygen saturation

Safety Net Advice (Very Important)

Tell parents to seek urgent care if:

Breathing becomes fast or difficult
Feeding drops (<50% normal)
Fewer wet nappies
Bluish lips / apnoea
Baby becomes drowsy or unresponsive

How to Explain to Parents (PLAB 2 Gold)

👉 “This is a common viral chest infection in babies. It usually gets worse for a few days, then improves on its own. We focus on keeping your baby comfortable, well-fed, and monitoring for any worsening.”

👉 “Most babies recover within 1–2 weeks, though a cough may last a bit longer.”

Key Exam Takeaways

Most common cause of wheeze in infants <1 year
Peaks day 3–5, resolves in 1–2 weeks
Supportive management only
No routine bronchodilators, steroids, or antibiotics