# Bronchiolitis

> Bronchiolitis for NEET-PG Paediatrics: RSV in infants, first wheeze, supportive care rules and monoclonal antibody prevention in exam notes.

- Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/bronchiolitis
- Exam / course: NEET-PG · Subject: Paediatrics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Bronchiolitis", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/bronchiolitis

## Direct answer

Bronchiolitis is an acute viral lower respiratory infection of the bronchioles, predominantly caused by respiratory syncytial virus (RSV), affecting children under two years with a peak around two to six months. Its hallmark is the first wheezing episode of an infant: coryza for a few days, then cough, tachypnoea, diffuse wheeze and crepitations with hyperinflation and feeding difficulty. Management is supportive — hydration and oxygenation, with ventilatory support for the few who deteriorate — since bronchodilators, steroids, antibiotics and physiotherapy are not routinely beneficial.

## What you must remember

- **Cause:** respiratory syncytial virus in most cases; human metapneumovirus, parainfluenza, rhinovirus, adenovirus and bocavirus account for the rest, with winter epidemics.
- **High-risk infants:** prematurity, chronic lung disease, congenital heart disease with increased pulmonary blood flow, immunodeficiency, age under three months and passive smoke exposure; apnoea may be the presenting sign in very young or preterm infants.
- **Pathophysiology:** viral inflammation and epithelial necrosis of small airways with mucus and oedema produce obstruction, air trapping, atelectasis and hyperinflation — hence the prolonged expiratory phase.
- **Clinical picture:** coryzal prodrome, then tachypnoea, recessions, nasal flaring, widespread fine crepitations with expiratory wheeze and poor feeding; hypoxaemia, not wheeze loudness, defines severity.
- **Investigations:** diagnosis is clinical; chest radiograph (hyperinflation, perihilar markings, patchy atelectasis) and viral testing are reserved for atypical or severe disease; pulse oximetry is the key monitor.
- **Treatment:** supportive — oxygen targeting saturations of about 90 per cent or above, nasal suction, and hydration by tube or intravenous fluids when feeding fails; bronchodilator trials only if objectively helpful; corticosteroids, antibiotics, physiotherapy and ribavirin are not routine (ribavirin only for the severely immunocompromised).
- **Prevention:** hand hygiene and smoke avoidance for all; passive immunisation of high-risk infants — monthly palivizumab historically, now joined by single-dose long-acting monoclonal antibody and maternal vaccination in several countries.

## Common confusion

Bronchiolitis is confused with a first asthma attack and with pneumonia. The bronchiolitis infant is under a year (usually under six months), in winter, with a first wheeze and viral prodrome, and typically fails to respond to bronchodilators — which itself argues for bronchiolitis over reactive airway disease. Pneumonia shows focal crepitations with high fever rather than diffuse symmetrical wheeze with hyperinflation. A third trap is deterioration timing: illness worsens over the first days before improving over one to two weeks, so the day-four feeding assessment matters.

## Exam-focused takeaway

NEET-PG tests bronchiolitis as a "what not to do" subject: the baby under six months with first wheeze receives oxygen, hydration and suction — not steroids, not routine antibiotics, not physiotherapy. Vignettes ask the next best step in a wheezing infant with poor feeding (assess saturation and hydration), the causative virus, and the high-risk features lowering the admission threshold. Prevention questions now include nirsevimab and maternal RSV vaccination alongside palivizumab.

## Frequently asked questions

### What causes bronchiolitis?

Respiratory syncytial virus in the large majority, with human metapneumovirus, parainfluenza, rhinovirus and adenovirus accounting for the rest.

### Why are bronchodilators and steroids not routine?

Trials show no consistent benefit — the disease is bronchiolar obstruction with debris and oedema, not bronchospasm these drugs reverse; a bronchodilator trial continues only if the infant responds objectively.

### When does an infant need admission?

For persistent hypoxaemia (around 90 per cent or below), poor feeding, apnoea, high-risk background, or when parents cannot monitor.

### Can bronchiolitis be prevented?

Partly — hygiene and smoke avoidance for all infants, plus passive immunisation for high-risk groups: monthly palivizumab, and newer options including single-dose long-acting monoclonal antibody and maternal vaccination.

### Can it present with apnoea?

Yes, especially in very young or preterm infants — apnoea may precede respiratory signs and is itself an indication for admission.