Bronchiolitis and oxygen or feeding support

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Respiratory syncytial virus is the commonest cause, but rhinovirus, human metapneumovirus, influenza, parainfluenza and other viruses can produce the same syndrome. Routine viral identification rarely changes individual supportive management.

Viral infection injures bronchiolar epithelium, producing oedema, mucus and sloughed cells. Narrow infant airways develop disproportionate resistance, causing air trapping, crackles, wheeze and ventilation-perfusion mismatch.

Work of breathing competes with feeding. Tachypnoea shortens suck-swallow-breathe pauses, while nasal obstruction is important because young infants preferentially breathe through the nose.

The illness commonly worsens over the first several days before improving. Cough may persist for 3 weeks, so trajectory and physiological stability matter more than complete symptom resolution.

History establishes onset, peak, apnoea, colour, feed fraction, wet nappies and home smoke exposure. Ask caregivers to compare current milk volume with the child's usual amount rather than with a generic target.

Examination should minimise distress. Observe before handling, count respiration for a full minute, assess recession and grunting, then examine hydration, perfusion, chest symmetry and cardiac findings.

Pulse oximetry is required in secondary care but does not replace judgement. Motion, poor perfusion, wrong probe position and device bias can mislead; persistent values require a good waveform and repeated observation.

Oxygen corrects hypoxaemia but does not reduce mucus obstruction. Low-flow nasal oxygen is commonly first; escalation is based on saturation, work, apnoea and gas exchange rather than a single flow rate.

Enteral hydration preserves gut function and can be delivered continuously or as cautious boluses according to work of breathing. Do not force oral feeds in a fatigued child at aspiration risk.

Antibiotics are reserved for a separate bacterial diagnosis. Fever alone is common, while high fever over 39°C or persistently focal signs increases the probability of pneumonia.

A discharge conversation includes expected cough, smoke avoidance, safe sleep, smaller feeds and how to recognise apnoea, cyanosis, worsening effort, exhaustion or dehydration.

Palivizumab or nirsevimab prevention policies apply to defined infants through national programmes and eligibility guidance; they are preventive antibodies, not acute bronchiolitis treatment.

Key points

Bronchiolitis is a clinical diagnosis in a child under 2 years: 1–3 days of coryza followed by persistent cough, tachypnoea or recession and wheeze or crackles, usually peaking on days 3–5.
Young infants can present with apnoea before typical chest signs. Record gestation, chronological age, comorbidity, feeding and previous apnoea explicitly.
First-line assessment is respiratory rate, work of breathing, alertness, colour, pulse oximetry with a correctly sized probe, hydration and observed ability to feed.
Do not diagnose severity from saturation alone. Borderline pulse oximetry can be inaccurate, including overestimation in darker skin; confirm a stable trace and interpret with the child.
NICE admission thresholds are persistent saturation below 90% from 6 weeks of age, or below 92% under 6 weeks or with an underlying condition; apnoea, severe distress and inadequate intake are independent indications.
Give supplemental oxygen at the same persistent thresholds. Titrate to remain at or above the relevant threshold and wean only when clinically stable, including through sleep.
First-line feeding support is small frequent oral feeds if safe. Use nasogastric or orogastric fluids when oral intake is inadequate; use intravenous isotonic fluid if enteral fluid is not tolerated or respiratory failure is impending.
Consider upper-airway suction only when secretions cause respiratory difficulty or feeding impairment; perform it in an infant with apnoea even if secretions are not obvious.
Do not routinely use salbutamol, nebulised adrenaline, ipratropium, corticosteroids, antibiotics, hypertonic saline or montelukast. Bronchiolitis is not an asthma exacerbation.
Do not routinely request chest radiography, blood tests or blood gas analysis. Radiographic changes can imitate pneumonia and drive unnecessary antibiotics.
Escalate to blood gas and respiratory support for severe worsening distress or suspected failure. High-flow or CPAP decisions follow the local paediatric respiratory pathway and senior review.
Before discharge, the child must be clinically stable, take adequate oral fluids and maintain room-air saturation for 4 hours including sleep: above 90% from 6 weeks, or above 92% when younger or with underlying disease.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Respiratory syncytial virus

RSV causes most seasonal cases, but identifying it does not usually alter the supportive treatment of an individual child.

Other respiratory viruses

Rhinovirus, metapneumovirus, influenza, parainfluenza and adenovirus can create an indistinguishable bronchiolar syndrome or coinfection. within the child-specific clinical phenotype.

Host vulnerability

Prematurity, young age, chronic lung or heart disease, neuromuscular weakness and immunodeficiency reduce respiratory reserve and increase apnoea or deterioration risk.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Small-airway inflammation
Viral epithelial injury produces bronchiolar oedema, mucus secretion and cellular debris within airways that are already narrow.
2
Expiratory obstruction
Partial small-airway blockage traps gas distally, while complete blockage creates atelectasis and heterogeneous ventilation. during progression of the respiratory disorder.
3
Gas-exchange mismatch
Patchy ventilation with preserved perfusion creates hypoxaemia; fatigue and widespread obstruction can later cause carbon-dioxide retention.
4
Feeding-respiratory competition
Tachypnoea and nasal obstruction disrupt suck-swallow-breathe coordination, reducing intake and increasing aspiration and dehydration risk. during progression of the respiratory disorder.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Typical sequence

Coryza precedes a persistent cough with tachypnoea or recession and bilateral wheeze or crackles in a child under 2 years.

Respiratory severity

Observe rate, recession, nasal flaring, grunting, air entry, colour, alertness, pauses and signs of fatigue before disturbing the child.

Oxygenation

Use an age-appropriate probe and stable trace, repeating borderline measurements and interpreting possible device bias with the clinical picture.

Feeding and hydration

Record percentage of usual intake, feed duration, cough or colour change, wet nappies, mucosa, fontanelle and perfusion.

Risk modifiers

Document age, gestation, chronic lung disease, significant heart disease, neuromuscular weakness, immunodeficiency and caregiver ability to observe deterioration.

Atypical features

High fever, focal signs, abrupt onset, persistent asymmetry or recurrent episodes should trigger a different diagnostic pathway.

Red flags requiring action

Observed or reported apnoea, central cyanosis, poor respiratory effort, exhaustion or reduced responsiveness requires emergency hospital care.
Severe respiratory distress with grunting, marked recession or respiratory rate above 70 breaths/minute meets a NICE admission criterion.
Persistent room-air oxygen saturation below 90% in a child aged at least 6 weeks, or below 92% under 6 weeks or with an underlying condition, meets an admission and oxygen threshold.
Fluid intake around 50–75% of usual, dehydration or inability to coordinate sucking with breathing may require admission and enteral or intravenous support.
Prematurity, age under 3 months, chronic lung disease, significant congenital heart disease, neuromuscular disease or immunodeficiency lowers the threshold for referral.
High fever, focal crackles, toxic appearance, recurrent focal wheeze or an atypical course should prompt reassessment for pneumonia, sepsis, foreign body or another diagnosis.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line: clinical assessment and pulse oximetryFirst stepFirst line
Why
Confirm the syndrome and determine respiratory, oxygen and feeding support needs.
Interpretation and limitations
Use persistent saturation with age, comorbidity, work, apnoea and intake; one transient reading does not define admission.
02
Observed oral feed
Why
Assess suck-swallow-breathe coordination and whether oral hydration is safe and adequate.
Interpretation and limitations
Fatigue, cough, desaturation or intake below need supports enteral feeding and admission rather than pressured oral intake.
03
Blood gas when respiratory failure is suspected
Why
Assess ventilation and acid-base status in severe worsening distress or exhaustion.
Interpretation and limitations
Rising carbon dioxide, worsening acidosis or poor effort indicates failure and accelerates senior respiratory-support review.
04
Chest radiograph only for an alternative question
Why
Assess suspected focal complication, pneumothorax or another diagnosis, not routine bronchiolitis.
Interpretation and limitations
Perihilar change and atelectasis are common and must not be interpreted automatically as bacterial pneumonia.
05
Targeted infection testing
Why
Investigate sepsis, pneumonia or cohorting requirements when clinical context indicates.
Interpretation and limitations
Viral status may support infection control, but a positive virus does not exclude bacterial coinfection or determine severity.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Viral-induced wheeze or asthma

Older age, recurrent episodic wheeze, interval symptoms, atopy and bronchodilator response support an asthma-spectrum illness rather than classic crackly bronchiolitis.

Pneumonia or sepsis

Toxic appearance, high fever, focal chest signs, poor perfusion or altered responsiveness suggests bacterial or systemic infection.

Congenital cardiac disease

Murmur, hepatomegaly, diaphoresis with feeds, poor growth or persistent cyanosis warrants cardiac evaluation. when timing, examination and trajectory are integrated.

Foreign-body aspiration

Abrupt choking, asymmetric air entry or unilateral hyperinflation is atypical for diffuse viral bronchiolitis. when timing, examination and trajectory are integrated.

Upper-airway or metabolic disease

Stridor, recurrent apnoea without coryza, hypoglycaemia or acidosis directs assessment away from isolated lower-airway viral illness.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01CommunityAssess referral riskFirst stepA child under 2 years has a typical bronchiolitis syndrome.

1Measure respiratory effort, saturation where available, hydration and observed or reported intake.
2Arrange emergency transfer for apnoea, cyanosis, severe distress or exhaustion; consider referral for persistent saturation below 92%, rate above 60, dehydration or reduced intake.
3Account for young age, prematurity, comorbidity and caregiver ability, and provide explicit safety-net advice if managed at home.

02OxygenUse age-specific thresholdsPersistent room-air hypoxaemia is confirmed on a reliable trace.

1Give oxygen below 90% from age 6 weeks, or below 92% under 6 weeks or with an underlying condition.
2Titrate and monitor through sleep while repeatedly assessing work and apnoea.
3EscalationEscalate respiratory support and obtain a blood gas if oxygen need, effort, exhaustion or ventilation worsens.

03FluidsSupport feeding stepwiseTachypnoea or fatigue prevents adequate safe oral feeding.

1Offer smaller frequent oral feeds only while coordination remains safe.
2Give nasogastric or orogastric fluid when oral intake is insufficient, using a regimen appropriate to respiratory state.
3Use intravenous isotonic fluid if enteral fluid is not tolerated or impending respiratory failure makes it unsafe.

04DischargeDemonstrate stability before homeRespiratory and feeding support are no longer thought necessary.

1Confirm clinical stability and adequate oral intake.
2Confirm room-air saturation for 4 hours including sleep above 90%, or above 92% for a child under 6 weeks or with underlying disease.
3Teach caregivers red flags, expected cough duration, smoke avoidance and whom to contact.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Apnoea and respiratory failure

Young or preterm infants may stop breathing or fatigue, requiring ventilation before marked wheeze develops. when recognition or effective treatment is delayed.

Dehydration and aspiration

Poor coordination and increased work reduce intake, while forced oral feeds can enter an unprotected airway.

Atelectasis and hypoxaemia

Mucus plugging produces regional collapse and ventilation-perfusion mismatch that can prolong oxygen need. when recognition or effective treatment is delayed.

Iatrogenic harm

Unnecessary radiography, bronchodilators, corticosteroids or antibiotics create adverse effects and distract from supportive reassessment. when recognition or effective treatment is delayed.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Trend respiratory rate, recession, alertness and apnoea; a falling rate with exhaustion is deterioration, not improvement.
Monitor saturation continuously when oxygen or significant support is required and intermittently when stable according to local policy.
Record actual intake, route, fluid balance and wet nappies, avoiding fluid overload during respiratory illness.
Reassess nasal obstruction and use gentle suction only when it changes breathing or feeding.
Review oxygen and fluid need through sleep and feeds before discharge.
Monitor pressure areas and abdominal distension with non-invasive support or enteral tubes.
At home, advise review for worsening effort, apnoea, cyanosis, exhaustion, markedly reduced intake or no wet nappy for 12 hours.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Thresholds change at 6 weeks

NICE uses the more cautious 92% oxygen and admission threshold for younger infants and any child with relevant underlying disease.

A low rate may be ominous

An exhausted infant can lose tachypnoea as respiratory effort fails, so alertness and air movement must be assessed together.

The best treatment is supportive

Oxygen, safe fluid, minimal handling and repeated assessment improve outcomes; common asthma medicines do not treat bronchiolar obstruction.

Radiographs create diagnostic momentum

Expected atelectasis can be labelled consolidation, leading to antibiotics without a compatible bacterial phenotype.

Feeding is a respiratory test

A child who appears settled at rest may reveal important fatigue, cough or desaturation during a normal feed.

11Common pitfallsFrequent interpretation and management errors.

01
Do not call every wheezing infant asthmatic or give a routine salbutamol trial.
02
Do not use saturation without confirming a reliable trace and examining the child.
03
Do not apply the 90% threshold to an infant under 6 weeks or a child with relevant underlying disease.
04
Do not force oral feeding through severe tachypnoea or fatigue.
05
Do not routinely order chest radiography, blood tests or viral testing.
06
Do not prescribe corticosteroids, bronchodilators, adrenaline, antibiotics or hypertonic saline routinely.
07
Do not perform deep or routine suction when secretions are not affecting breathing or feeds.
08
Do not discharge before stability is shown through sleep and adequate oral intake.