Episode 33 – Acute Bronchiolitis: Assessment and Management in the Emergency Department (Pharmacology CME)

Show Notes

Differentiating bronchiolitis from asthma and reactive airway disease in young children can be challenging, and a rapidly changing clinical presentation can confound accurate assessment of the severity of the illness. This episode reviews risk factors for apnea and severe bronchiolitis; discusses treatments/therapies and provides evidence-based recommendations for the management of pediatric patients with bronchiolitis.


  • Bronchiolar narrowing and obstruction is caused by:
    • Increased mucus secretion
    • Cell death and sloughing
    • Peri-bronchiolar lymphocytic infiltrate
    • Submucosal edema
  • Smooth muscle constriction seems to have a limited role, perhaps explaining the lack of response to bronchodilators.
  • Median duration of illness is 12 days in children <24 months
  • 18% still ill at 3 weeks.2
  • 9% still ill at 4 weeks.2


  • RSV accounts for 50-80% of cases, but rare in children >2 yo.3
    • Late fall epidemic peaking Nov-March, in the US.4
  • Human Metapneumovirus (HMPV) accounts for 3-19% 5,6
    • Similar seasonal variation to RSV.
  • Parainfluenza, influenza, adenoviruses, coronaviruses, rhinoviruses, and enteroviruses are other causes.4-6
  • Rhinoviruses have been shown to play a larger role in Asthma.7


  • The American Academy of Pediatrics defines it as any of the following in infants: 1
    • Rhinitis
    • Tachypnea
    • Wheezing
    • Cough
    • Crackles
    • Use of accessory muscles
    • Nasal flaring

Differential Diagnosis

  • Emergent Causes
    • Infection: pneumonia, chlamydia, pertussis
    • Foreign body: aspirated or esophageal
    • Cardiac anomaly: congestive heart failure, vascular ring
    • Allergic reaction
    • Bronchopulmonary dysplasia exacerbation
  • Non-acute Causes
    • Congenital anomaly: tracheoesophageal fistula, bronchogenic cyst, laryngotracheomalacia
    • Gastroesophageal reflux disease
    • Mediastinal mass
    • Cystic fibrosis
  • Clinical Pearls
    • Vomiting, wheezing, and coughing associated with feeding; consider GERD.
    • Wheezing associated with position changes; consider tracheomalacia or great vessel anomalies.
    • Wheezing exacerbated by flexion of neck and relieved by neck hyperextension; consider vascular ring.
    • Multiple respiratory tract infections and failure to thrive; consider cystic fibrosis or immunodeficiency.
    • Wheezing with heart murmur, cardiomegaly, cyanosis, exertion or sweating with feeding; consider cardiac disease.
    • Sudden onset of wheezing and choking; consider foreign body.

Risk Factors for Severe Bronchiolitis

  • Age < 6-12 weeks11-13
  • Prematurity < 35-37 weeks’ gestation11-13
  • Underlying respiratory illness such as bronchopulmonary dysplasia1
  • Significant congenital heart disease; immune deficiency including HIV, organ or bone marrow transplants, or congenital immune deficiencies14,15
  • Altered mental status (impending respiratory failure)
  • Dehydration due to inability to tolerate oral fluids
  • Ill appearance12
  • Oxygen saturation level ≤ 90%1
  • Respiratory rate: > 70 breaths/min or higher than normal rate for patient age1,12
  • Increased work of breathing: moderate to severe retractions and/or accessory muscle use1
  • Nasal flaring
  • Grunting

Risk Factors for Apnea

  • Full-term birth and < 1 month of age16,17
  • Preterm birth (< 37 weeks’ gestation) and age < 2 months post birth11-13,17
  • History of apnea of prematurity
  • Emergency department presentation with apnea17
  • Apnea witnessed by a caregiver17

Diagnostic Testing

  • Xray
    • Radiographs increase the likely hood of a physician giving antibiotics, even if the X-ray is negative.18-20
    • Routine radiography is discouraged, but may be helpful when severe disease requires further evaluation or exclusion of foreign body.
  • Viral testing is not necessary for the diagnosis but may help when searching for the cause of fever in young infants.
    • 2016 ACEP fever guidelines note that positive viral testing can impact further workup of fever for a serious bacterial infection (SBI).21
  • In infants <28 days, serious bacterial infection is high, even in patients with bronchiolitis: 10% (RSV+) and 14% (RSV -)22. Standard fever evaluation is recommended.
  • In the 28-60 day old group, SBI rates were 5.5% (RSV+) and 11.7% (RSV-). All were UTIs.22 Urinalysis is recommended.

Emergency Department Treatment

  • Oxygen
    • Keep O2 saturation >90%
    • Clinicians may choose not to use continuous pulse oximetry (weak recommendation due to low-level evidence and reasoning)1
  • Fluids
    • IV or NG administration of fluids to combat dehydration, until respiratory distress and tachypnea resolve.
  • Suctioning
    • Routine use of “deep” suctioning may not be beneficial and may be harmful.1
    • Nasal suction should be used to help infants with respiratory distress, poor feeding or sleeping.
  • Bronchodilators1,25,26
    • Generally nor recommended for routine use.
    • May trial in infants with:
    • Severe bronchiolitis (these were excluded in the studies).
    • History of prior wheezing.
    • Family history of atopy/asthma in an older infant.
  • Anticholinergic Agents (ipratropium bromide)
    • No evidence for improvement in bronchiolitis.31-34
  • Corticosteroids
    • AAP1, Cochrane Review27, and PECARN28 study all recommend against, finding no evidence for improvement.
    • One small study (70 patients) found a benefit utilising 1 mg/kg oral dexamethasone followed by 0.6 mg/kg daily for 5 days. However, the study limited by size and increased prevalence of family history of atopy.
    • Recommendations remain against use in first time wheezers with bronchiolitis.
  • Racemic Epinephrine
    • Not recommended1. Further study needed.
  • Racemic Epinephrine + Oral Dexamethasone
    • Pediatric Emergency Research Canada trial at 8 Canadian pediatric EDs involving 800 infants aged 6 weeks to 12 months with bronchiolitis found that the epinephrine-dexamethasone group had a lower admission rate over 7 days than the placebo group (17.1% vs 26.4%). This was not statistically significant. Further study needed. 30
  • Hypertonic Saline
    • AAP guidelines do not recommend use in the ED but note clinicians may utilize it in the inpatient setting. 1
    • Cochrane reviews in 2013 and 2017 found some inpatient benefit, but a conflicting publication found it may worsen cough.35-37
  • High Flow Nasal Cannula (HFNC)
    • Several small pediatric ICU studies show a benefit in severe cases. No large ED randomized trials exist, to date.
    • Study protocols included weight based or age based flow rates.
  • Nasal CPAP
    • Shows benefit in pediatric ICU settings. Evidence vs HFNC is limited.


  • Consider admission if any of the following are present:
    • Risk for apnea
    • Risk for severe bronchiolitis
    • Respiratory distress, particularly if it interferes with feeding
    • Hypoxia (oxygen saturation ≤ 90%)
    • Decreased feeding and/or dehydration
    • An unreliable caregiver (ie, unable to ensure patient care and appropriate 24-hour follow-up)
  • All patients with severe bronchiolitis should be admitted.

Last Updated on January 25, 2023

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