Bronchiolitis
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Direct answer
Respiratory syncytial virus causes the majority of bronchiolitis — a first-time wheezy lower respiratory illness of infants under two years, peaking at two to six months in winter — and the diagnosis is clinical: coryza, then tachypnoea, expiratory wheeze, chest hyperinflation and feeding difficulty. Treatment is deliberately boring: nasal suction, hydration and oxygen for saturation below 90-92 per cent, with admission for infants who feed under half normal, have respiratory rates above 60-70, marked recession, apnoea or hypoxia. Bronchodilators are a trial at most (continue only if objectively better), and systemic steroids, chest physiotherapy, routine antibiotics and antivirals are not recommended — the exam tests what not to give as much as what to give.
What you must remember
- Epidemiology: RSV accounts for most cases (rhinovirus, parainfluenza, metapneumovirus follow); nearly all children are infected by two years, with seasonal peaks in the Indian winter.
- Age rule: first wheezy episode under two years with coryzal onset is bronchiolitis until proven otherwise; recurrent episodes beyond infancy suggest early asthma or an alternative anatomical cause.
- Severity and admission thresholds: feeding less than half of normal, respiratory rate above 60-70 per minute, severe recession or grunting, SpO2 below 90 (AAP) to 92 (NICE) per cent on room air, apnoea, or high-risk status (under three months, ex-preterm, congenital heart disease, chronic lung disease).
- Oxygen: the only therapy that changes outcomes beyond support — keep saturation at or above 90-92 per cent; wean rather than chase normalisation to 100.
- What not to do: routine bronchodilators (a single trial may be justified, continuing only with documented improvement), systemic or inhaled corticosteroids, chest physiotherapy, antibiotics, and empirical antivirals — repeated loud teaching points in modern guidelines.
- Hypertonic saline 3 per cent nebulisation modestly shortens hospital stay in some settings and is used in Indian practice, but evidence is mixed; it is not standard in guideline minima.
- Apnoea: young infants, especially ex-preterm under about two months postnatal age, may present with apnoea before wheeze — admit and monitor any bronchiolitic under three months.
- Prevention: palivizumab 15 mg/kg intramuscularly monthly through the RSV season for selected high-risk infants (under six months with chronic lung disease, significant congenital heart disease, extreme prematurity); household hand hygiene and avoiding smoke exposure remain the population measures.
Deciding home or ward
A five-month-old, born at term, has two days of runny nose and now breathes 58 times a minute with subcostal recession, takes 100 mL per feed instead of 180 mL, and saturates 93 per cent in room air. Walk the decision. First the physiology: feeding is the infant's exercise tolerance, and halved feeds with that respiratory rate crosses the admission line in most protocols. On the ward: gentle nasal suction before feeds, small frequent feeds or nasogastric supplementation if sucking exhausts her, and oxygen by nasal prongs only if saturation dips below 90-92 — titrated to a target, not to comfort. A single salbutamol trial may be given; no objective improvement means stop, not increase. Watch for grunting, drowsiness or apnoea, remembering the illness peaks at day three to five. Discharge when feeding recovers and saturations hold overnight in air, with advice that cough may lag two to three weeks and that a small subgroup will have recurrent post-bronchiolitic wheeze. No steroid prescription at the door; that is the test of whether the lesson stuck.
Where students slip
The great conflation is bronchiolitis with "baby asthma": steroids and repeated bronchodilators feel active but do nothing, and the exam rewards knowing that supportive care is the standard. Second slip: the age and episode count — a first episode under two is bronchiolitis, whereas recurrent episodic wheeze between attacks points to asthma, and a first episode with choking onset or focal monophonic wheeze demands a foreign-body question. Third: the X-ray — hyperinflation and patchy atelectasis may appear, but radiology neither confirms nor excludes, and reading atelectasis as "pneumonia" is what generates the unnecessary amoxicillin prescription that guidelines warn against.
Frequently asked questions
Which virus most commonly causes bronchiolitis?
Respiratory syncytial virus, transmitted by contact and droplets, with highest severity in infants under six months, ex-preterms and those with cardiac or chronic lung disease.
What are the admission criteria for bronchiolitis?
Poor feeding (under half of intake), respiratory rate above 60-70 with marked recession, SpO2 below about 90-92 per cent in air, apnoea, and high-risk infants such as those under three months or ex-preterm.
Which treatments are explicitly not recommended?
Routine bronchodilators, systemic or inhaled corticosteroids, chest physiotherapy, empirical antibiotics and ribavirin in ordinary cases — care is suction, hydration and oxygen.
When does apnoea occur in bronchiolitis?
Mainly in infants under two to three months and ex-preterm babies, sometimes as the presenting sign before wheeze, requiring inpatient cardiorespiratory monitoring.
Who receives palivizumab prophylaxis?
Selected high-risk infants — under six months with chronic lung disease or significant congenital heart disease, and extremely premature babies — 15 mg/kg intramuscularly monthly during the RSV season.