Bronchiolitis and viral lower respiratory tract infection — branching viva

Opening

Examiner: A 4-month-old arrives in winter with two days of a runny nose and cough, now breathing fast with recession, diffuse crackles and wheeze, feeding half normal and saturating 91 percent. How do you approach her? [1]

Candidate: I would make a clinical diagnosis of bronchiolitis — a first viral lower respiratory tract infection in an infant under twelve months — and grade its severity by observation before disturbing her, keeping her settled on her carer's lap. She has moderate work of breathing, feeding around half and saturations of 91 percent, which places her in the moderate band. My plan is supportive care: support feeding, give oxygen if saturations stay below target, and reassess serially, while deliberately not reaching for bronchodilators or steroids. [1] [5]

Branch 1 — supportive care and the drugs you withhold

Examiner: Why not give her a salbutamol trial for the wheeze? [2]

Candidate: Because the obstruction in bronchiolitis is mechanical — sloughed epithelium, oedema and mucus in the small airways — rather than reversible bronchospasm, and infant bronchioles have little smooth muscle to relax. The Cochrane review of bronchodilators found no meaningful benefit in oxygenation, admission or length of stay, so salbutamol is not part of routine care, and the same applies to adrenaline, corticosteroids, antibiotics and physiotherapy. [2] [1]

Examiner (probe): What oxygen saturation target would you use, and why? [4]

Candidate: I aim for a target of around 90 to 92 percent. The BIDS equivalence trial showed that a 90 percent target was as safe as a 94 percent target while reducing oxygen use and length of stay, so I titrate oxygen to that lower target rather than chasing normal saturations, and I interpret the number alongside her feeding and work of breathing. [4] [1]

Branch 2 — the deteriorating infant

Examiner: An hour later the nurse says she has gone quiet and settled. Reassured? [1]

Candidate: Not automatically — I would go and look. An infant who becomes quiet with falling respiratory effort, worsening colour and reduced responsiveness may be tiring rather than improving, and that is impending respiratory failure. I would reassess her fully, and if she is deteriorating I would escalate breathing support and call for senior and intensive care help rather than waiting. [1] [5]

Examiner (probe): How would you escalate her breathing support? [3]

Candidate: I would step up from standard oxygen to high-flow nasal cannula, which the Franklin trial showed reduces treatment escalation in infants failing standard oxygen, then to CPAP, and finally consider intubation and intensive care for genuine respiratory failure. High-flow is a rescue for those who fail standard oxygen, not a first-line treatment for every infant. [3] [1]

Branch 3 — the young infant and apnoea

Examiner: A different infant is 5 weeks old, ex-premature, with coryza and one reported blue floppy episode, but a nearly normal chest. Same approach? [1]

Candidate: No — I would admit and monitor him. That episode is likely apnoea, which in a young or ex-premature infant can be the presenting feature of bronchiolitis before the chest signs, and it may recur, so the reassuring chest examination is misleading. I would observe him with continuous oximetry and apnoea monitoring, support feeding, and be ready to escalate breathing support. [1] [5]

Examiner (probe): Would a chest X-ray help you? [1]

Candidate: No. Bronchiolitis is a clinical diagnosis and imaging is not routine; the hyperinflation and patchy atelectasis are easily misread as consolidation, which drives unnecessary antibiotics. I reserve a chest radiograph for atypical, severe or deteriorating cases or a suspected complication, not for a typical infant. [1] [5]

Close

Examiner: Summarise your safe approach to bronchiolitis in one line. [1]

Candidate: Diagnose it clinically, grade it by work of breathing, oxygen and feeding, support feeding and give targeted oxygen with high-flow and CPAP as rescue, withhold the drugs that do not work, and stay alert for apnoea in the young infant and for the atypical picture hiding a mimic. [1] [3]