Bronchiolitis Module

Cite this article as:
Tessa Davis. Bronchiolitis Module, Don't Forget the Bubbles, 2020. Available at:
AuthorTessa Davis
DurationUp to 2 hours
Equipment requiredNone
  • Basics (10 mins)
  • Main session: (2 x 15 minute) case discussions covering the key points and evidence
  • Advanced session: (2 x 20 minutes) case discussions covering grey areas, diagnostic dilemmas; advanced management and escalation
  • Sim scenario (30-60 mins)
  • Quiz (10 mins)
  • Infographic sharing (5 mins): 5 take home learning points

We also recommend printing/sharing a copy of your local guideline.

A 7 month old infant presents on Day 4 of the illness. He has mild to moderate work of breathing. Sats 95% in air. He is taking around half his normal feeds.

What investigations and treatment options should you consider?

Why doesn’t salbutamol work in this age group?

How do you know when to admit?

See the PREDICT systematic review of all treatments

  • Salbutamol – there is no benefit in using salbutamol in infants with bronchiolitis (and some evidence of adverse effects)
  • Nebulised adrenaline – no clinically useful benefit (there is evidence for temporary effect but not for improvement in outcome)
  • Nebulised hypertonic saline – there is weak evidence of a reduction in length of stay of 0.45 days. However when two studies were removed, both of which used a different discharge criteria than most hospitals, there was no benefit. This is not recommended routinely, although the authors suggest that it should be used only as part of an RCT
  • Glucocorticoids – no benefit
  • Antibiotics – not recommended (The risk of a secondary bacterial infection is very low, and there is potential harm from giving antibiotics)
  • Oxygen – no evidence of benefit in infants with no hypoxia, and low level evidence that maintaining the sats over 91% with oxygen actually prolongs the length of stay. There are no reports of long-term adverse neurodevelopmental outcomes in infants with bronchiolitis, however there is also no data on the safety of targeting sats <92%. Commence oxygen therapy to maintain sats over 91%.
  • Sats monitoring – there is moderate evidence suggesting that continuous sats monitoring increases the length of stay in stable infants
  • High flow – there is low to very-low level evidence of benefit with high flow
  • Chest physiotherapy – not recommended
  • Saline drops – routine saline drops are not recommended but a trial with feeds may help
  • Feeds – both NG and IV are acceptable routes for hydration

See Beta receptor mythbusting (from

A 6 month old infant presents on Day 3 of the illness. She has moderate to severe work of breathing. Sats are 91% in air. She is struggling to feed at home.

What management options would you consider?

See the PARIS Paper

This is the biggest and most robust trial yet done to assess the value of high-flow in bronchiolitis. The primary outcome shows that there is a role for high-flow in the non-ICU management of this disease. Importantly PARIS has shown in a large cohort of children that high-flow, when used within the parameters of the trial protocol, does not lead to an increase in adverse events which in-turn suggests the increased patient:nurse ratios for kids on high-flow that are often mandated by hospital policies may not be necessary (depending on the severity of disease of course). Some caution must be used around the potential for erroneous use of the high-flow circuits themselves and the interpretation of early warning scores in the context of high-flow use.

PARIS was supported with significant nursing education resources potentially reducing errors to a level that were below what could be expected with the standard resourcing of mixed EDs and other environments where high-flow use in children may be infrequent. As with many grey areas in medicine protocols as to how we use high-flow vary by institution with little more than opinion to guide them.

Though neither the intention nor the conclusion of this paper in showing the progress of such a large number of children on high-flow, this trial also provides a basis for more robust decision making around how we use high-flow itself.

NICE feeding guidance

  • Give fluids by nasogastric or orogastric tube in children with bronchiolitis if they cannot take enough fluid by mouth.
  • Give intravenous isotonic fluids (see the NICE guideline on intravenous fluids therapy in children) to children who: do not tolerate nasogastric or orogastric fluids; or have impending respiratory failure.

Do you know how to set up high flow? (8 minutes)

How to set up Airvo 2 (Optiflow)  (3.5mins)

How to use Airvo 2 (6 mins)

You have a 12 month old, with two days of coryza and one day of increased work of breathing symptoms.

How do you manage them?

How do you figure out whether they have bronchiolitis or VIW?

Practically speaking, we know that bronchiolitis and viral induced wheeze have two quite different management pathways, but it is not as if a child moves from being 12 months old to 13 months old and therefore cannot have bronchiolitis (or vice versa for viral induced wheeze). These conditions as previously mentioned, exist on a spectrum. 

  • What has been the onset of symptoms? Progressive over days is most consistent with bronchiolitis. Onset of wheeze and respiratory distress over hours is most consistent with bronchospasm (viral induced wheeze).
  • What has been the pattern of their work of breathing? 
  • How significant is the work of breathing? 
  • What are the auscultation findings – is there presence of focal findings? Wheeze? Crackles? 
  • Is this affecting the child functionally with feeding or sleeping difficulties?
  • If auscultation is suggestive of possible viral induced wheeze or at least, a component of wheeze that may be responsive to bronchodilators (If wheeze is present and no crackles or focal findings) and presuming the child has more than just mild work of breathing -then we suggest this may be a possible candidate for viral induced wheeze.  
  • (Note – This is a good opportunity to survey your team and colleagues to see what the practice is at your local department). 
  • Regarding this grey area question, in Australian practice, some clinicians will trial salbutamol for potential viral induced wheeze if the child is 12 months or older. Other doctors may wish to trial if the child is slightly younger (e.g. from 10 months) if they have a strong family history of asthma and atopy or if they have had previous ventolin use reported by their family with good effect. The younger the child is, the less likely that the story and case is to fit viral induced wheeze.

It would be prudent to give 6 puffs (or do you use another number?) and reassess following to see if there is any improvement or change.

You’ve started high flow 2L/kg for a four month old with bronchiolitis, moderate work of breathing and saturations of 88% and titrated FiO2 up to 30% to maintain saturations. However they are still intermittently desaturating so you titrate them up to 40% FiO2.

They have ongoing work of breathing with a respiratory rate of 60-70.

What are your next steps?

Consider revisiting history, respiratory examination and consider adjuncts to assessment such as a capillary or venous blood gas.

  • For example, Do they have an NG tube on free drainage, are they nil by mouth and on IV fluid support at ⅔ maintenance
  • Are their family actually compliant with this or have also been feeding them via a bottle? 
  • Are they working harder to breathe because they are getting “hangry” and might actually tolerate a continuous NG or comfort feed?
  • Consider whether the HFNP has led to no change, improvement and then deterioration or simple worsening of symptoms due to patient distress.
  •  If no improvement was observed on commencement – it may be worth de-escalating them – ie. lower flow rates or low flow nasal prongs

Consider your confidence of whether you have the right diagnosis or if there is need to assess for a secondary pathology such as pneumonia, foreign body, cardiac contribution? Do you need to further investigate with bloods, CXR? Do you need to append your management and provide antibiotic coverage? Do you need to assess for a complication from treatment e.g. pneumothorax.

  • Have you sought a senior review/notified the admitting paediatrician?
  • Do you need an ICU consult, NETS consult or retrieval to a tertiary centre?
  • How long are you comfortable to wait to see if there is a response to high flow?
  • What settings would you start on?
  • Where could you move up to (in terms of peep, FiO2)
  • How soon would you reassess – what are you looking for?

  • How would you determine this?
  • Who should be involved in the conversation? Who should perform the intubation?
  • What sedation would you use?
  • What equipment would you use?
  • What settings would you use?

In bronchiolitis, children do not respond to salbutamol because:

A: They don’t have beta receptors until they are older.

B: The beta receptors are immature and do not begin functioning correctly until the child is older.

C: The large amount of secretions interfere with it and prevent it binding to the receptors

D: There is no bronchospasm for the salbutamol to act on.

The correct answer is D.

All humans have beta receptors. Foetuses develop them from around 15 weeks gestation and are therefore born with them. Developing beta receptors after 1 year of age is a common paediatric myth! In fact, in bronchiolitis, there is no bronchospasm in the same way as there is in viral induced wheeze. Bronchiolitis is a illness developing gradually over 4 days and then slowly improving. Patients have increased mucous rather than bronchospasm, which does not respond to a bronchodilator.

A 3 month old baby presents to ED with coryza, cough, and poor feeding. Breastfeeding is going ok, but the baby is feeding for shorter periods, more frequently than usual. She is having wet nappies as normal. Saturations are 93% on room air, RR is 62, and there is moderate subcostal recession with some nasal flaring. Which of the following is an indication to admit this baby to hospital?

A: The reduced breastfeeding

B: The oxygen sats

C: The work of breathing

D: The age of the baby

The correct answer is C.

The criteria for admission usually are:

  • feeding less than half of usual, or less wet nappies
  • saturations less than 92% on air
  • increased WOB
  • apnoeic episodes

Risk factors such as:

  • Ex-prem
  • Age less than 12 weeks or less than 37 weeks CGA
  • history of lung disease or congenital heart disease or neurological problems
  • smoke exposure

In clinical practice, you would use your judgement to assess if hospitalisation was necessary. Social concerns should always be considered.

In this case, the baby is maintaining good urine output and the feeds, although shorter, are more frequent. The age alone is not an indication for admission. Obviously, an O2 requirement would be an indication for admission but most units would consider sats of 92% or less as reduced. There is significantly increased work of breathing with recession and nasal flaring, however, so this would be the main indication for admission.

You have a 10 month old baby with bronchiolitis who is to be commenced on high flow. Which of the following is false?

A: Nasal prongs size should be estimated based on the width of the patient’s nostrils.

B: Patients can be NG fed immediately once on high flow. 

C: High flow improves the functional residual capacity.

D: The humidified oxygen help clearing mucous secretions.

The correct answer is B.

Patients on high flow will likely need an NG inserted due to abdominal distention, but should usually not be fed for the first couple of hours on high flow. The aim of high flow is to provide humidified, high flow to improve clearance of secretions and to increase the functional residual capacity. Together this should reduce the work of breathing.

Please download our Facilitator and Learner guides


Cite this article as:
Henry Goldstein. Bronchiolitis, Don't Forget the Bubbles, 2013. Available at:

A 6-month-old child presents with cough and runny nose for 2 days with increased work of breathing.  She is working hard with moderate subcostal recession. Once you hear the cough, it can only mean one thing….the start of bronchiolitis season.


Bottom Line

  • Bronchiolitis is a common lower respiratory tract illness in children under 2 years.
  • The natural course of bronchiolitis lasts 7-10 days, with day 2-3 being the most severe.
  • Be aware of the risk factors for severe bronchiolitis.
  • If the clinical picture and course doesn’t ‘fit the script’, reconsider the diagnosis.
  • Consider a broad range of differential diagnoses in a child presenting with increased work of breathing and fever.
  • Be aware of the ‘overlap’ between bronchiolitis/viral-induced wheeze and asthma.


What is it?

Bronchiolitis is, as the name suggests, inflammation of the small bronchi and bronchioles. The clinical entity we know as bronchiolitis is the most common admission diagnosis in patients under 2, accounting for high morbidity in this population. More succinctly;

“A seasonal viral illness characterized by fever, nasal discharge, and dry, wheezy cough. On examination, there are fine inspiratory crackles and/or high-pitched expiratory wheeze.” – The University of Nottingham, in their 2009 Acute Breathing Difficulty Guideline.

It is most often caused by respiratory syncytial virus (50-80%), as well as parainfluenza (especially PIV3), human metapneumovirus, influenza, rhinoviruses, and adenovirus. In the words of my first general paediatric consultant:

“Bronchiolitis is a typical winter illness, which almost every child gets in their first two years of life. What matters is first, how old you are when you get it, and secondly, what kind of condition you’re in.”


What are the clinical features?

Several days of upper respiratory tract symptoms, including fever, rhinorrhoea, and coryza. These develop into a wheeze, tachypnea, increased work of breathing, moist cough, and fevers. The increased work of breathing often leads to decreased oral intake, with or without dehydration. In infants, poor feeding and apneas with or without cyanosis may be present.

Auscultation of the lungs may reveal a wheeze and transmitted upper airway sounds. A focal zone with decreased air entry or coarse crackles is more consistent with pneumonia.

It is well described that a typical course of bronchiolitis lasts 7-10 days, with night 2-3 being the most severe. In this respect, it is important to reconsider the diagnosis in any patient not ‘sticking to the script’, or deteriorating after initial improvement. A cough may last for up to four weeks.



The diagnosis is primarily clinical. Clinical features of an area of the lung with decreased air entry or consistent focal crackles warrant a chest radiograph to exclude pneumonia. A chest radiograph infrequently adds to the clinical picture and is not routine.

Some clinicians will obtain a nasopharyngeal aspirate or flocculated swab for respiratory virus PCR. There is also a rapid antigen test, which is good for ruling in, rather than ruling out, a particular virus.

Although typing of the respiratory virus causing bronchiolitis may be helpful for bed management and nursing, it is unlikely to alter management.

This point remains controversial as knowledge of the causative organism may allow some prognostication regarding illness course and prevent unnecessary antibiotic usage. It does not rule out dual respiratory tract pathology, such as secondary bacterial infection.

In particular, there is merit to obtaining swabs in patients with risk factors for severe infection, thus:


Risk Factors for Severe Infection

  • Age <1 yo, especially less than 6 weeks
  • Congenital heart disease
  • Neurological conditions
  • Chronic respiratory illness
  • Pulmonary hypertension
  • Ex-premature infants
  • Inborn errors of metabolism
  • Trisomy 21
  • Cystic fibrosis
  • Immunodeficiency
  • A previous severe bronchiolitis illness requiring CPAP or PICU admission.


Around 50% of children with severe infections have none of the above risk factors.

Children at risk of severe infection and mild symptoms should be admitted and observed.

As noted earlier, the course of the illness is that night 2-3 is usually the most severe, thus any child presenting earlier will potentially worsen, sometimes quite rapidly.


How do we manage it?

Management is supportive, with rehydration and fluid maintenance whilst unable to feed and respiratory support as required. If the child is unlikely to deteriorate and does not require inpatient observation or additional support, they can often be managed in the outpatient setting. It’s essential to provide clear safety-net advice for when to return to ED as well as strongly encouraging an early GP review.


Admit for observation

Infants <6/52 and patients with the risks for severe infection above are at risk of apnoeas, so cardiorespiratory monitoring is indicated. Oxygen saturation monitoring is indicated in all children. Keep a close eye on work of breathing and hydration as these can change as the illness progresses.


What level of oxygen saturation is acceptable?

There are differing opinions regarding target oxygen saturation in patients with bronchiolitis. Most would agree on a target somewhere between ≥94% and ≥92%. But which?

Consider the oxygen-haemoglobin dissociation curve:



Conditions that push the curve to the right (higher PO2 to maintain SaO2 and curve has a steeper gradient), are decreasing pH, increasing temperature.

Thus, in a febrile, acidotic child the curve is pushed to the right, requiring a higher PO2 to maintain the same level of saturation and thus increasing the likelihood of desaturations. In these children, aiming for an SaO2 of 94% would be reasonable. Local guidelines may have differing suggestions.


Respiratory support

Oxygen delivery can be via nasal cannulae, or if bronchiolitis severe by high-flow humidified oxygen via nasal prongs.  High-flow provides continuous positive airway pressure (CPAP) and aims to avoid intubation.

Flow rates of 2l/kg/min provide a PEEP of 4-8cm, improving the functional residual capacity.

In life-threatening cases, sedation, intubation and ventilation may be necessary and should be done with PICU and senior support. In regional and rural settings, it’s important to be aware of local limitations and consider early transfer to a tertiary centre for deteriorating, high-risk patients. For the care of such patients, make early contact with your regional Paediatric Emergency Transfer Services.



Children with acute illness are susceptible to SIADH and hyponatremia. Thus, it’s important that whilst supporting the increased insensible losses and decreased intake as a result of respiratory distress we don’t over hydrate the patient. Around 2/3 maintenance for an infant not tolerating oral intake is sufficient to both hydrate and reduce the likelihood of SIADH. Most paediatric departments would use 0.9% saline and 5% dextrose.

In mild cases of bronchiolitis, small, frequent feeds may provide sufficient hydration. As respiratory distress increases, nasogastric feeds (continuous vs bolus) may be required. For a child with severe bronchiolitis, on high-flow nasal prongs or moderately dehydrated, intravenous therapy is indicated.


Other Therapies

Antibiotics are not indicated for bronchiolitis, nor is there a benefit in the use of steroids, nebulized adrenaline, or bronchodilators. Additionally, there is no benefit in physiotherapy or macrolide antibiotics.

Although salbutamol does not alter the clinical course of bronchiolitis, in the case of a strong family history of atopic disease or asthma it would not be unreasonable to trial a course of salbutamol, particularly in the child >6 yo who is presenting with a wheeze.

It’s important to assess the child pre- and post-salbutamol for both subjective and objective clinical response. This may also have some utility in differentiating between viral bronchitis and a viral-induced wheeze. Again, this is a controversial sub-topic with evolving evidence.

Bronchiolitis has a broad range of differential diagnoses; it is important to consider these, particularly if the patient is not responding as expected to your initial management, or if there are features of the history or examination of an alternative diagnosis.


What’s the differential?

Pneumonia or other pulmonary infections, including mycoplasma and pertussis – listen for focal crackles or signs, productive cough or radiological features of pneumonia. These patients will usually have a fever, in addition to cough and tachypnoea. Consider viral, bacterial, chlamydial or mycoplasma pneumonia. This is a common alternative diagnosis for bronchiolitis.

Recurrent viral-triggered wheezing – another common alternative diagnosis, viral-triggered wheeze may present quite similarly. Features in the history that might point you towards a viral-induced wheeze, is that of an antecedent URTI which had resolved, followed by wheeze and work of breathing a few days later, with or without fever. Differentiating between RSV bronchiolitis and a viral-induced wheeze can be particularly challenging.

Meningitis – most consultants can describe a patient who presents during a “bronchiolitis epidemic” who has meningitis. Always consider this differential diagnosis. Although it’s had to find case reports in the medical literature, unfortunately, the lay press has many examples of this.

Foreign body aspiration – characterized by rapid onset and failure of initial management. May have a low-grade fever. Have a high index of suspicion.

Croup – usually stridor rather than a wheeze, and with a similar gamut of causative organisms. Laryngotracheobronchitis can present with a wheeze in a child with bronchitic disease.

Aspiration pneumonia – consider more strongly in children with poor airway protection, including spastic cerebral palsy, or in any child having seizures or convulsions.

Gastro-oesophageal reflux – up to 40-50% of infants with GORD present with wheeze or respiratory symptoms. There is also an association with chronic cough.

Asthma – an acute exacerbation is less likely to have fevers, and will often have a personal history of atopy or allergy, or a family history of asthma. It would be rare to diagnose a child under two with asthma at a first presentation to the hospital with a wheeze.

Chronic pulmonary disease – chronic neonatal lung disease or prematurity predisposes the child to respiratory infections.

A mediastinal mass – there are multiple case reports of mediastinal masses presenting with a wheeze and respiratory distress.

Tracheoesophageal fistula – late-presentation of H-type tracheoesophageal fistula may present as coughing, abdominal distension, and recurrent chest infections. Sundar’s well described 1975 case series can be found here.

Congenital heart disease and heart failure – to be considered in any neonate presenting with increased work of breathing, with or without apneas. These patients will look unwell, with a constellation of symptoms including disproportionate tachycardia, poor perfusion with or without cyanosis, weak femoral pulses & murmurs.

Vascular ring, congenital lobar emphysema or a bronchogenic cyst  – may also present in neonates with a “bronchiolitis-sounding” history.


Selected references

Coffin. S,E., Bronchiolitis: In-Patient Focus, Pediatric Clinics of North America – Volume 52, Issue 4 (August 2005).

Grimes, A. All That Wheezes… HOSPITAL PEDIATRICS Vol. 2 No. 1 January 1, 2012 pp. 47 -50

Zorc, JJ & Breese Hall, C. Bronchiolitis: Recent Evidence on Diagnosis and Management. Pediatrics. Vol. 125 No. 2 February 1, 2010  pp. 342 -349 (doi: 10.1542/peds.2009-2092).

Marlais M, Evans J, Abrahamson E. Arch Dis Child 2011;96:648-652 doi:10.1136/adc.2010.201079 Clinical predictors of admission in infants with acute bronchiolitis.

Royal Children’s Hospital, Melbourne. Clinical practice guidelines : Bronchiolitis.

Paediatric Grand Rounds – Acute Viral Bronchiolitis in Children by Dr Nitin Kapur, Respiratory Paediatrican. Lecture on 5th June 2013 @ Royal Children’s Hospital, Herston QLD. Slides.

Fitzgerald, D.A. & Kilham, H.A., Bronchiolitis: assessment and evidence based management. MJA 2004; 180(8): 399-404.

Lakhanpaul M, Armon K, Eccleston P, et al. An Evidence Based Guideline for the Management of Children Presenting With Acute Breathing Difficulty. Nottingham, United Kingdom: University of Nottingham; 2002. 

Louie, M C & Bradin, S. Foreign Body Ingestion and Aspiration Pediatrics in Review August 2009; 30:295-301.

Sheikh S, Allen E, Shell R, Hruschak J, Iram D, Castile R, McCoy K. Chronic aspiration without gastroesophageal reflux as a cause of chronicrespiratory symptoms in neurologically normal infants. Chest. 2001 Oct;120(4):1190-5. PMID: 11591559.

Saglani, S., et al. Investigation of young children with severe recurrent wheeze: any clinical benefit? Eur Respir J 2006 27:29-35; doi:10.1183/09031936.06.00030605. 

Sheikh S, Stephen T, Howell L, Eid N. Gastroesophageal reflux in infants with wheezing. Pediatr Pulmonol. 1999 Sep;28(3):181-6. PMID: 10495334.

National Asthma Council Australia. Asthma Management Handbook 2006. Melbourne, 2006.

Heinz, P. & Dunne, J. Wheeze and mediastinal mass: A challenging patient. Emergency Medicine Vol 16(3)241-243, June 2004. DOI: 10.1111/j.1742-6723.2004.00573.

Sundar, B., Guiney, E.J. & O’Donnell, E. Congenital H-type tracheo-oesophageal fistula. Arch. Dis. Ch. 1975 (50)862. 

Hsu, D. & Pearson G., Heart Failure in Children. Part I: History, Etiology, and Pathophysiology. Circ Heart Fail 2009;2;63-70; DOI: 10.1161/CIRCHEARTFAILURE.108.820217.

Phelan, E., Ryan, S. & Rowley, H. Vascular rings and slings: interesting vascular anomalies. The Journal of Laryngology & Otology (2011), 125, 1158–1163.