Bronchiolitis in Children

Quick Reference Card

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Overview

Bronchiolitis is the most common lower respiratory tract infection in infancy and a leading cause of hospitalisation in children under 12 months of age. [3] It is an acute viral illness characterised by inflammation and obstruction of the small airways (bronchioles), resulting in respiratory distress, cough, wheeze, and crackles on auscultation.

The condition predominantly affects infants aged 2-6 months, coinciding with waning maternal antibody protection and the peak of respiratory syncytial virus (RSV) circulation during winter months. [4] RSV accounts for 50-80% of cases, with rhinovirus, human metapneumovirus, parainfluenza viruses, and influenza comprising the remainder. [5]

Management is fundamentally supportive: ensuring adequate oxygenation, maintaining hydration, and minimising unnecessary interventions. Multiple high-quality randomised controlled trials have demonstrated no benefit from bronchodilators, corticosteroids, or antibiotics in typical bronchiolitis, leading to strong recommendations against their routine use in international guidelines. [1,2,6]

Clinical Pearl: The "Rule of 3s": Bronchiolitis typically worsens for the first 3 days, plateaus for 2-3 days, then improves over 3-5 days. The total illness duration is 10-14 days, though cough may persist for 3-4 weeks. Educate parents that worsening before improvement is expected.

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Epidemiology

Incidence and Prevalence

Bronchiolitis affects virtually all children by age 2 years, with clinically significant disease occurring in a substantial minority. [3]

Seasonal Distribution

The COVID-19 pandemic significantly disrupted RSV seasonality globally, with a delayed surge following relaxation of non-pharmaceutical interventions. [10]

Demographics and Risk Factors

High-Risk Groups for Severe Disease

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Aetiology

Viral Causes

RSV remains the dominant pathogen, though improved viral detection has revealed significant contributions from other respiratory viruses. [5,11]

Viral Co-detection

Multiple viruses are detected in 10-30% of hospitalised cases. [11] The clinical significance remains debated:

• Some studies suggest increased severity with co-infection
• Others show no difference in outcomes
• RSV-rhinovirus co-detection may predict prolonged wheeze

Exam Detail: RSV Biology:

• Single-stranded RNA virus, Paramyxoviridae family
• Two major structural proteins: F (fusion) and G (attachment)
• Two subtypes: RSV-A and RSV-B (A often more severe)
• Incubation period: 2-8 days
• Viral shedding: 3-8 days (up to 3-4 weeks in immunocompromised)
• No latency, reinfection occurs throughout life
• Natural immunity wanes within 1-2 years

Transmission:

• Large droplet spread (within 6 feet)
• Direct contact with secretions
• Fomite transmission (survives on surfaces for hours)
• Highly contagious: R0 estimated at 3-5

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Pathophysiology

Mechanism of Disease

The pathological hallmark of bronchiolitis is acute inflammation and obstruction of the bronchioles (airways less than 2mm diameter). [12]

Sequence of Events:

1. Viral inoculation: RSV enters via nasopharyngeal mucosa (contact/droplet transmission)

2. Upper respiratory phase: Viral replication in nasopharyngeal epithelium causing coryza, rhinorrhoea (days 1-3)

3. Lower respiratory spread: Virus spreads to bronchiolar epithelium via cell-to-cell transmission and aspiration of secretions

4. Epithelial damage: Ciliated epithelial cells undergo necrosis and sloughing into the airway lumen

5. Inflammatory response:

   • Peribronchiolar lymphocytic infiltration
   • Submucosal oedema
   • Mucus hypersecretion
   • Neutrophil recruitment

6. Airway obstruction: Combined effect of:

   • Epithelial debris
   • Mucus plugging
   • Inflammatory oedema
   • Smooth muscle has minimal role (hence bronchodilators ineffective)

7. Air trapping and atelectasis:

   • Partial obstruction → ball-valve mechanism → hyperinflation
   • Complete obstruction → absorption atelectasis
   • V/Q mismatch → hypoxemia

8. Resolution: Epithelial regeneration over 2-4 weeks, residual bronchial hyperreactivity may persist

Exam Detail: Immunological Response:

The immune response to RSV is complex and contributes to both viral clearance and disease severity:

• Innate immunity: Pattern recognition receptors (TLR4, TLR3, RIG-I) detect RSV, triggering interferon production and inflammatory cytokines (IL-6, IL-8, TNF-alpha)

• Adaptive immunity: CD8+ cytotoxic T cells critical for viral clearance; CD4+ Th2 response associated with more severe disease

• Immature infant immunity:

  • Reduced interferon response
  • Th2-skewed immunity
  • Waning maternal antibodies
  • These factors contribute to age-related severity

• RSV immune evasion: Non-structural proteins NS1 and NS2 inhibit type I interferon signalling

Histopathology:

• Bronchiolar epithelial necrosis
• Peribronchiolar mononuclear cell infiltration
• Submucosal oedema
• Intraluminal debris and mucus
• Varying degrees of smooth muscle hyperplasia (minimal in acute phase)

Why Infants Are Particularly Vulnerable

Clinical Pearl: Poiseuille's Law Applied: Airway resistance is inversely proportional to the fourth power of the radius. A 1mm reduction in a 4mm infant bronchiole increases resistance 16-fold, whereas the same reduction in an 8mm adult airway increases resistance only 2-fold.

Disease Course

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Clinical Presentation

Symptoms

Prodromal Phase (1-3 days):

• Rhinorrhoea (clear initially, may become mucopurulent)
• Nasal congestion
• Sneezing
• Low-grade fever (38-39°C; > 39°C consider bacterial co-infection)
• Decreased appetite
• Mild cough

Progressive Phase:

• Worsening cough (typically wet)
• Increased respiratory rate
• Noisy breathing (wheeze audible to parents)
• Increased work of breathing
• Feeding difficulty (cannot coordinate suck-swallow-breathe)
• Decreased urine output
• Irritability or lethargy

Examination Findings

Vital Signs

Age-Appropriate Respiratory Rate Thresholds:

Work of Breathing Assessment

Clinical Pearl: Grunting is a Red Flag: Expiratory grunting represents the infant's attempt to maintain positive end-expiratory pressure by partially closing the glottis. It indicates significant alveolar disease and is a sign of severe illness requiring urgent intervention.

Auscultatory Findings

General Examination

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Severity Assessment

Clinical Severity Scoring

While multiple scoring systems exist, clinical assessment integrating multiple parameters remains the gold standard. [13]

Apnoea Risk Assessment

Apnoea is the most concerning complication in young infants and may be the presenting feature before other respiratory signs develop. [14]

Clinical Pearl: Apnoea may precede respiratory distress: In young infants, apnoea can be the initial presentation of bronchiolitis, occurring before cough, wheeze, or significant tachypnoea develop. Any apnoea in an infant with respiratory symptoms mandates admission for continuous monitoring.

Oxygen Saturation Interpretation

Important Considerations:

• Brief desaturations during coughing or feeding are common
• Persistent SpO2 less than 90% at rest indicates significant disease
• Recent AAP guidelines suggest SpO2 ≥90% as acceptable threshold [1]
• UK NICE guidelines also use 90% as oxygen initiation threshold [2]

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Differential Diagnosis

Primary Differentials

Red Flag Features Suggesting Alternative Diagnosis

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Investigations

Clinical Diagnosis

Bronchiolitis is a clinical diagnosis. [1,2]

Routine investigations are NOT recommended for typical presentations. Excessive testing increases:

• Cost
• Parental anxiety
• Length of stay
• Risk of unnecessary antibiotic use (for non-specific CXR changes)

When to Investigate

Evidence Debate: The "Routine CXR" Debate:

Multiple studies demonstrate that routine CXR in bronchiolitis:

• Leads to unnecessary antibiotic prescriptions (up to 2× higher) [15]
• Shows non-specific changes (atelectasis, peribronchial thickening) in most cases
• Rarely changes management
• May prolong length of stay

The AAP strongly recommends AGAINST routine CXR. [1]

When CXR IS appropriate:

• Severe disease requiring PICU
• Clinical deterioration
• Atypical features (focal signs, persistent high fever)
• Comorbidities (cardiac, immunodeficiency)
• Failure to improve as expected

Typical CXR findings in bronchiolitis (when performed):

• Hyperinflation (flattened diaphragms, increased AP diameter)
• Peribronchial thickening ("dirty lung fields")
• Patchy atelectasis (especially right upper lobe)
• Rarely: lobar consolidation (consider bacterial superinfection)

Viral Testing

Value of Viral Testing:

• Cohorting to prevent nosocomial transmission
• Epidemiological surveillance
• May inform prognosis (RSV vs rhinovirus)
• Does NOT change acute management

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Management

Core Principles

The Three Pillars of Bronchiolitis Management:

1. Oxygenation: Maintain SpO2 ≥90%
2. Hydration: Ensure adequate fluid intake
3. Minimal intervention: Avoid unnecessary treatments

Clinical Pearl: "Less is More": The strongest evidence in bronchiolitis management is AGAINST most interventions. Supportive care alone is the gold standard. This is a paradigm shift that many healthcare providers still struggle to accept.

Supportive Care

Nasal Suctioning

Evidence Base:

• Infants are obligate nasal breathers
• Nasal obstruction directly impairs feeding and breathing
• Deep or frequent suctioning can cause mucosal trauma and increase secretions
• Saline drops before suctioning may help loosen secretions (limited evidence)

Positioning and Handling

Feeding and Hydration

NG vs IV Fluids:

• NG feeding preferred if tolerated (maintains gut function, more physiological)
• IV fluids for severe distress, significant vomiting, or NG intolerance
• Use isotonic fluids (0.9% saline with 5% dextrose) at 2/3 maintenance rate
• Reduced maintenance due to SIADH risk in respiratory illness

Exam Detail: IV Fluid Calculation (2/3 Maintenance):

Full maintenance (Holliday-Segar):

• 100 mL/kg/day for first 10 kg
• 50 mL/kg/day for next 10 kg
• 20 mL/kg/day for each kg > 20 kg

For bronchiolitis: Calculate maintenance then give 67% of this rate

Example: 8 kg infant

• Maintenance = 8 × 100 = 800 mL/day = 33 mL/hr
• 2/3 maintenance = 22 mL/hr of 0.9% saline/5% dextrose

Oxygen Therapy

Low-Flow Nasal Cannula

Indications:

• SpO2 less than 90% on room air (some guidelines use less than 92%)
• Maintain SpO2 ≥90% (≥92% in some high-risk patients)

High-Flow Nasal Cannula (HFNC)

HFNC has revolutionised bronchiolitis management, providing non-invasive respiratory support between standard oxygen and CPAP. [16]

Mechanism of Benefit:

• Washout of nasopharyngeal dead space
• Provision of low-level CPAP (2-5 cmH2O)
• Reduced work of breathing
• Improved oxygenation
• Heated humidification reduces airway resistance

Evidence for HFNC:

The PARIS trial [16] and TRAMONTANE study [17] demonstrated:

• Reduced treatment failure compared to standard oxygen
• Reduced need for ICU admission
• Safe for use outside PICU settings
• No difference in length of stay

Clinical Pearl: HFNC Failure Criteria: If no improvement within 60-90 minutes of HFNC at maximum flow with FiO2 0.5-0.6, escalation to CPAP or intubation should be considered. Signs of failure include: persistent RR > 70, worsening retractions, declining SpO2, exhaustion.

Weaning Oxygen

Interventions NOT Recommended

Bronchodilators (NOT Routinely Recommended)

Why Bronchodilators Don't Work:

• Bronchiolitis involves bronchiolar inflammation and mucus, not bronchospasm
• Infant airway smooth muscle is immature
• Obstruction is predominantly from debris and oedema

When to Consider a Bronchodilator Trial:

• Older infant (> 12 months) with recurrent wheezing
• Strong family history of asthma/atopy
• Prominent audible wheeze
• If trialled: give single dose, assess response, continue ONLY if clear improvement

Evidence Debate: The "Bronchodilator Trial" Controversy:

Some clinicians still advocate for a "therapeutic trial" of salbutamol. The evidence is clear:

• Meta-analyses show no benefit in typical bronchiolitis [6]
• Any perceived improvement is likely placebo effect or natural disease fluctuation
• Side effects (tachycardia, irritability) may worsen the clinical picture
• Continued use after a "positive trial" lacks evidence

The AAP and NICE both recommend AGAINST routine bronchodilator use. A single observed trial in selected older infants with significant wheeze and atopic history may be reasonable, but the burden of proof is on demonstrating clear benefit.

Corticosteroids (NOT Recommended)

Why Steroids Don't Work:

• Inflammation in bronchiolitis is predominantly neutrophilic, not eosinophilic
• Viral-induced pathology is not steroid-responsive
• Steroids target the wrong inflammatory pathway

Antibiotics (NOT Indicated Unless Bacterial Co-infection)

Bronchiolitis is a VIRAL infection.

Antibiotics NOT indicated for:

• Routine bronchiolitis (even if CXR shows "infiltrates")
• Low-grade fever
• Mucopurulent nasal discharge (normal in viral URTI)
• Elevated CRP alone (viral inflammation elevates CRP)

Other Interventions NOT Recommended

Exam Detail: Hypertonic Saline - The Nuanced View:

Cochrane review (2017) [20] findings:

• Modest reduction in length of stay in hospitalised patients (0.5 days)
• No benefit in ED or outpatient settings
• Mechanism: osmotic effect to mobilise secretions, reduce mucosal oedema
• Typical regimen: 3% saline 4 mL nebulised every 6-8 hours

Current guidance:

• AAP (2014): Does not recommend routine use
• NICE (2015): May be considered in hospitalised infants
• Clinical practice varies widely

Palivizumab (Prevention, Not Treatment)

New RSV Vaccines and Monoclonal Antibodies (2023-2024):

• Maternal RSV vaccination (Abrysvo) approved for pregnant women
• Nirsevimab: long-acting monoclonal antibody, single dose provides season-long protection
• Both represent major advances in RSV prevention

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Disposition

Discharge Criteria

All of the following should be met:

Admission Criteria

ICU/HDU Admission Criteria

Follow-Up Recommendations

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Patient and Family Education

Explaining Bronchiolitis to Parents

Key Messages:

1. What it is: "Bronchiolitis is a chest infection caused by a virus that makes the small breathing tubes in your baby's lungs inflamed and blocked with mucus."

2. What to expect: "It usually gets worse before it gets better. Days 3-5 are often the worst. Your baby should start to improve after about a week, but the cough can last 3-4 weeks."

3. No cure, but will recover: "There is no medicine that can kill the virus. We support your baby while they fight the infection themselves. Most babies recover fully."

4. What we're doing: "We are helping with oxygen if needed, making sure your baby stays hydrated, and keeping their nose clear so they can breathe and feed more easily."

Home Care Instructions

Warning Signs - Return Immediately

Reducing Transmission

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Prognosis and Outcomes

Short-Term Outcomes

Long-Term Outcomes

Exam Detail: Post-Bronchiolitis Wheezing and Asthma:

The relationship between bronchiolitis and subsequent asthma is complex:

• RSV bronchiolitis: Associated with increased risk of recurrent wheeze, but causation vs association debated

• Rhinovirus bronchiolitis: Stronger association with asthma development, may be a marker of atopic predisposition

• Possible mechanisms:

  • Viral-induced airway damage leading to hyperreactivity
  • Altered immune response (Th2 skewing)
  • Underlying atopic predisposition manifesting as bronchiolitis

• Prevention of asthma: No evidence that treating bronchiolitis differently (steroids, etc.) prevents subsequent asthma

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Special Populations

Preterm Infants

Congenital Heart Disease

Management:

• Early cardiology involvement
• Lower threshold for PICU admission
• Consider palivizumab prophylaxis
• Monitor for heart failure exacerbation

Chronic Lung Disease (BPD)

• Baseline respiratory compromise
• Prolonged oxygen requirement
• Lower threshold for admission and escalation
• Consider palivizumab prophylaxis
• May need home oxygen adjustment

Immunocompromised Infants

• Prolonged viral shedding (weeks to months)
• Risk of severe and persistent disease
• May benefit from ribavirin (rarely used)
• Strict infection control measures
• Consider immunology input

Infants less than 6 Weeks

• Highest risk for apnoea (central apnoea, immature respiratory control)
• Lower threshold for admission regardless of apparent severity
• Continuous cardiorespiratory monitoring
• May present with apnoea before respiratory distress
• Ensure adequate observation before discharge

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Quality Metrics and Documentation

Key Performance Indicators

Documentation Checklist

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Exam Preparation

Common Exam Questions

1. "What are the causes of bronchiolitis and which is most common?"

2. "Describe your approach to a 3-month-old infant with bronchiolitis and SpO2 of 88%."

3. "What is the evidence regarding bronchodilator use in bronchiolitis?"

4. "When would you admit an infant with bronchiolitis?"

5. "A parent asks why you're not giving antibiotics for their baby's chest infection. How do you respond?"

6. "What are the risk factors for severe bronchiolitis?"

7. "Describe the role of high-flow nasal cannula in bronchiolitis."

8. "An infant with bronchiolitis has an apnoeic episode. What is your management?"

Viva Points

Viva Point: Opening Statement: "Bronchiolitis is an acute viral lower respiratory tract infection primarily affecting infants under 12 months, most commonly caused by RSV. It is characterised by bronchiolar inflammation, mucus plugging, and small airway obstruction, presenting with coryza, cough, tachypnoea, wheeze, and crackles. Management is supportive, focusing on oxygenation and hydration, with strong evidence against routine use of bronchodilators, steroids, and antibiotics."

Key Statistics to Quote:

• RSV causes 50-80% of cases [5]
• Peak age: 2-6 months [4]
• Hospitalisation rate: 2-3% of infants less than 12 months [7]
• Mortality less than 0.5% in developed countries [3]

Evidence to Cite:

• AAP Clinical Practice Guideline 2014 [1]
• NICE NG9 Guidelines 2015/2021 [2]
• PARIS Trial for HFNC [16]
• Cochrane reviews for bronchodilators [6], steroids [19], and epinephrine [18]

Common Mistakes That Fail Candidates

Model Answer

Q: "A 4-month-old infant presents with 3 days of coryza, now tachypnoeic with subcostal recession and wheeze. SpO2 is 91% on room air. How would you manage this patient?"

A: "This infant has moderate bronchiolitis based on the clinical presentation. My immediate management would follow the ABCs:

Airway and Breathing: I would apply supplemental oxygen via nasal cannula to maintain SpO2 ≥90%. Given the moderate work of breathing, I would consider high-flow nasal cannula at 2 L/kg/min, which evidence from the PARIS trial shows can reduce treatment failure.

Circulation/Hydration: I would assess hydration status and feeding ability. If feeding less than 50% normal, I would establish NG feeds, or IV fluids at 2/3 maintenance if in significant distress.

Supportive measures: Gentle nasal suctioning before feeds, minimal handling, and parental presence.

I would NOT routinely give:

• Bronchodilators - meta-analyses show no benefit in bronchiolitis
• Corticosteroids - Cochrane review shows no benefit
• Antibiotics - this is a viral infection
• Chest X-ray - unless diagnostic uncertainty

I would admit this infant because of oxygen requirement and moderate respiratory distress. I would arrange continuous SpO2 monitoring and reassess frequently.

I would educate parents that peak severity is expected around days 3-5, improvement expected over 7-14 days, and what warning signs to watch for.

Discharge criteria would include SpO2 ≥90% on room air for at least 4 hours, adequate feeding, minimal work of breathing, and confident carers with follow-up arranged."

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Key Clinical Pearls

Diagnostic Pearls

• Bronchiolitis is a CLINICAL diagnosis - routine testing not indicated
• Peak illness at days 3-5 - warn parents it may worsen before improving
• First episode of wheeze in an infant less than 12 months = bronchiolitis, not asthma
• Apnoea may be the presenting sign before respiratory distress, especially in young infants
• CXR often shows non-specific changes - avoid as it prompts unnecessary antibiotics

Treatment Pearls

• Supportive care is the ONLY evidence-based treatment
• Bronchodilators do NOT work in bronchiolitis (unlike asthma)
• Steroids do NOT help - save them for croup and asthma
• Antibiotics do NOT help - it's viral
• Nasal suctioning is KEY - infants are obligate nasal breathers
• HFNC can reduce ICU admission - evidence supports its use

Disposition Pearls

• Admit if unsure - bronchiolitis can deteriorate rapidly
• High-risk infants warrant lower admission thresholds
• Age less than 6 weeks = very low threshold for admission (apnoea risk)
• Educate, educate, educate - parents need clear guidance on warning signs
• Arrange follow-up within 24-48 hours for all discharged patients

Communication Pearls

• Parents expect "treatment"
• explain why supportive care is best
• Use clear language: "fighting the virus themselves"
• Provide written instructions with specific warning signs
• Acknowledge parental anxiety while providing reassurance
• "Come back if worried" is an essential message

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References

1. Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. Pediatrics. 2014;134(5):e1474-e1502. doi:10.1542/peds.2014-2742

2. National Institute for Health and Care Excellence. Bronchiolitis in children: diagnosis and management (NG9). 2015 (updated 2021). Available at: https://www.nice.org.uk/guidance/ng9

3. Meissner HC. Viral bronchiolitis in children. N Engl J Med. 2016;374(1):62-72. doi:10.1056/NEJMra1413456

4. Hall CB, Weinberg GA, Iwane MK, et al. The burden of respiratory syncytial virus infection in young children. N Engl J Med. 2009;360(6):588-598. doi:10.1056/NEJMoa0804877

5. Florin TA, Plint AC, Zorc JJ. Viral bronchiolitis. Lancet. 2017;389(10065):211-224. doi:10.1016/S0140-6736(16)30951-5

6. Gadomski AM, Scribani MB. Bronchodilators for bronchiolitis. Cochrane Database Syst Rev. 2014;2014(6):CD001266. doi:10.1002/14651858.CD001266.pub4

7. Hasegawa K, Tsugawa Y, Brown DF, Mansbach JM, Camargo CA Jr. Trends in bronchiolitis hospitalizations in the United States, 2000-2009. Pediatrics. 2013;132(1):28-36. doi:10.1542/peds.2012-3877

8. Nair H, Nokes DJ, Gessner BD, et al. Global burden of acute lower respiratory infections due to respiratory syncytial virus in young children: a systematic review and meta-analysis. Lancet. 2010;375(9725):1545-1555. doi:10.1016/S0140-6736(10)60206-1

9. Schuh S, Kwong JC, Englesbe M, et al. Factors associated with pediatric intensive care unit admission for children with bronchiolitis. J Pediatr. 2021;238:233-240.e2. doi:10.1016/j.jpeds.2021.07.026

10. Foley DA, Yeoh DK, Minney-Smith CA, et al. The interseasonal resurgence of respiratory syncytial virus in Australian children following the reduction of coronavirus disease 2019-related public health measures. Clin Infect Dis. 2021;73(9):e2829-e2830. doi:10.1093/cid/ciab099

11. Mansbach JM, Piedra PA, Teach SJ, et al. Prospective multicenter study of viral etiology and hospital length of stay in children with severe bronchiolitis. Arch Pediatr Adolesc Med. 2012;166(8):700-706. doi:10.1001/archpediatrics.2011.1669

12. Johnson JE, Gonzales RA, Olson SJ, Wright PF, Graham BS. The histopathology of fatal untreated human respiratory syncytial virus infection. Mod Pathol. 2007;20(1):108-119. doi:10.1038/modpathol.3800725

13. Destino L, Weisber JN, Golden WC, Brady PW. Bronchiolitis: update on evidence-based supportive treatments. Curr Opin Pediatr. 2020;32(3):466-473. doi:10.1097/MOP.0000000000000908

14. Ralston S, Hill V. Incidence of apnea in infants hospitalized with respiratory syncytial virus bronchiolitis: a systematic review. J Pediatr. 2009;155(5):728-733. doi:10.1016/j.jpeds.2009.04.063

15. Schuh S, Lalani A, Allen U, et al. Evaluation of the utility of radiography in acute bronchiolitis. J Pediatr. 2007;150(4):429-433. doi:10.1016/j.jpeds.2007.01.005

16. Franklin D, Babl FE, Schlapbach LJ, et al. A randomized trial of high-flow oxygen therapy in infants with bronchiolitis. N Engl J Med. 2018;378(12):1121-1131. doi:10.1056/NEJMoa1714855

17. Milési C, Essouri S, Pouyau R, et al. High flow nasal cannula (HFNC) versus nasal continuous positive airway pressure (nCPAP) for the initial respiratory management of acute viral bronchiolitis in young infants: a multicenter randomized controlled trial (TRAMONTANE study). Intensive Care Med. 2017;43(2):209-216. doi:10.1007/s00134-016-4617-8

18. Hartling L, Bialy LM, Vandermeer B, et al. Epinephrine for bronchiolitis. Cochrane Database Syst Rev. 2011;2011(6):CD003123. doi:10.1002/14651858.CD003123.pub3

19. Fernandes RM, Bialy LM, Vandermeer B, et al. Glucocorticoids for acute viral bronchiolitis in infants and young children. Cochrane Database Syst Rev. 2013;2013(6):CD004878. doi:10.1002/14651858.CD004878.pub4

20. Zhang L, Mendoza-Sassi RA, Wainwright C, Klassen TP. Nebulised hypertonic saline solution for acute bronchiolitis in infants. Cochrane Database Syst Rev. 2017;12(12):CD006458. doi:10.1002/14651858.CD006458.pub4