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.
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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