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.

Pathophysiology

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

Etiology

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

Presentation

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.

Disposition

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.

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

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