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Bronchiolitis
Dennis E. Hughes, DO, FACEP
image BASICS
DESCRIPTION
  • Inflammation and obstruction of small airways and reactive airways generally affecting infants and young children—upper respiratory infection (URI) prodrome followed by increased respiratory effort and wheezing
  • Usual course: insidious, acute, progressive
  • Leading cause of hospitalizations in infants and children in most Western countries
  • Predominant age: newborn-2 years (peak age <6 months). Neonates are not protected despite transfer of maternal antibody.
  • Predominant sex: male > female
EPIDEMIOLOGY
Incidence
  • 21% in North America
  • May be seasonal (October-May in the Northern Hemisphere) and often occurs in epidemics
  • 18.8% (90,000 annually) of all pediatric hospitalizations (excluding live births) in children <2 years
  • Incidence increasing since 1980 (with concomitant increase in relative rate of hospitalization from 2002 to 2007).
ETIOLOGY AND PATHOPHYSIOLOGY
RSV accounts for 70-85% of all cases (children <12 months of age), but rhinovirus, parainfluenza virus, adenovirus, influenza virus, Mycoplasma pneumoniae, and Chlamydophila pneumoniae have all been implicated:
  • Infection results in necrosis and lysis of epithelial cells and subsequent release of inflammatory mediators.
  • Edema and mucus secretion, which combined with accumulating necrotic debris and loss of cilia clearance, results in airflow obstruction.
  • Ventilation-perfusion mismatching resulting in hypoxia
  • Air trapping is caused by dynamic airways narrowing during expiration, which increases work of breathing.
  • Bronchospasm appears to play little or no role.
RISK FACTORS
  • Secondhand cigarette smoke
  • Low birth weight, premature birth
  • Immunodeficiency
  • Formula feeding (little or no breastfeeding)
  • Contact with infected person (primary mode of spread)
  • Children in daycare environment
  • Congenital cardiopulmonary disease
  • < 12 weeks of age
GENERAL PREVENTION
  • Handwashing or use of alcohol-based hand rubs (preferred)
  • Contact isolation of infected babies
  • Persons with colds should keep contact with infants to a minimum.
    • Breastfeeding of infants has been associated with reduced morbidity of disease.
  • Palivizumab (Synagis), a monoclonal product, administered monthly, October-May, 15 mg/kg IM; used for RSV prevention ONLY in high-risk patients
Pediatric Considerations
Prior infection does not seem to confer subsequent immunity.
COMMONLY ASSOCIATED CONDITIONS
  • Upper respiratory congestion
  • Conjunctivitis
  • Pharyngitis
  • Otitis media
  • Diarrhea
image DIAGNOSIS
History and physical examination should be the basis for the diagnosis of bronchiolitis.
PHYSICAL EXAM
  • Tachypnea
  • Retractions (increased work of breathing)
  • Rhinorrhea
  • Wheezing
  • Upper respiratory findings: pharyngitis, conjunctivitis, otitis
DIFFERENTIAL DIAGNOSIS
  • Other pulmonary infections such as pertussis, croup, or bacterial pneumonia
  • Aspiration
  • Vascular ring
  • Foreign body
  • Asthma
  • Heart failure
  • Gastroesophageal reflux
  • Cystic fibrosis
DIAGNOSTIC TESTS & INTERPRETATION
Laboratory and other ancillary testing (including chest x-ray) are not required if clinical diagnosis is bronchiolitis.
Initial Tests (lab, imaging)
  • Arterial oxygen saturation by pulse oximetry. Results need to be interpreted in clinical context. Transient hypoxemia is a common phenomenon in healthy infants (1).
  • Rapid respiratory viral antigen testing is not necessary during RSV season because the disease is managed symptomatically but may be useful for epidemiologic, hospital cohorting, or in the very young to reduce unnecessary other workup; also indicated in infants admitted while receiving palivizumab prophylaxis (if positive, prophylaxis may be discontinued).
  • The American Association of Pediatrics (AAP) does not recommend routine RSV testing in infants and children with bronchiolitis.
  • Chest x-ray findings are variable and may include atelectasis, peribronchial cuffing, hyperinflation, and perihilar infiltrates.
image TREATMENT
The cornerstone of therapy is supportive to include upper airway suctioning, prevention of significant and prolonged hypoxia, and dehydration. The other interventions noted have historically varying effect on the course of the illness despite numerous studies. Recent clinical practice guidelines do not support the routine use of corticosteroids, bronchodilators, or epinephrine. Parental education and support is vital (1)[A].
MEDICATION
First Line
  • Humidified oxygen for hypoxia of <90% (pulse oximetry should be interpreted in context of clinical appearance of infant) (1)[C]
  • Nebulized hypertonic saline (3%) can be effective in reducing LOS in hospitalized patients but not recommended use in the ED (1,2)[B].
  • Antibiotics only if secondary bacterial infection present (rare). Not indicated for routine use (1)[B].
  • Positive-pressure ventilation (PPV) in the form of continuous positive airway pressure (CPAP) can be used in cases of respiratory failure. There is limited clinical evidence other than observational studies (3)[C].
  • High-flow nasal cannula oxygen widely used in various settings to improve oxygen saturation with resultant reduction in end-tidal CO2 (ETCO2) and respiratory rate, but overall effectiveness remains unproven to date (3)[C].
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ADDITIONAL THERAPIES
  • Ribavirin (palivizumab) for patients at high risk (for prophylaxis per CDC/AAP guidelines) (4)[A]
  • Heliox therapy (70% helium and 30% oxygen) may be of benefit early in moderate to severe bronchiolitis to reduce degree of respiratory distress due to air flow restriction, but Cochrane review found little evidence of sustained benefit at 24 hours (5)[A].
  • Although not routinely recommended, inhaled β-agonists (albuterol) can be effective in selected cases (particularly in patients with a history of bronchospasm).
INPATIENT CONSIDERATIONS
Bronchiolitis can be associated with apnea in children <6 weeks of age.
Admission Criteria/Initial Stabilization
  • Respiratory rate >45 breaths/min with respiratory distress or apnea
  • Hypoxia is common so clinical criteria are more helpful (pulse oximetry <94% used by many as cutoff).
  • Ill or toxic appearance
  • Underlying heart condition, respiratory condition, or immune suppression
  • High risk for apnea (age <30 days, preterm birth [<37 weeks])
  • Dehydrated or unable to feed
  • Uncertain home care
  • Use of Respiratory Distress Assessment Instrument may aid in determining admission. The five best predictors of admission, age, respiratory rate, heart rate, oxygen saturation, and duration of symptoms, were recently incorporated into a scoring instrument.
  • Supplemental oxygen for pulse oximetry <94% on room air if clinically indicated. AAP recommends O2 saturation >90% if infant otherwise well.
IV Fluids
Indicated only if tachypnea precludes oral feeding; weight-based maintenance rate plus insensible losses.
Discharge Criteria
Normal respiratory rate and no oxygen requirement: Recent small studies suggest that after a period of observation, children can be safely discharged on home oxygen with home health follow-up.
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
  • Hospitalization is usually required only if oxygen is a requirement or unable to feed/drink.
  • For a hospitalized patient, monitor as needed depending on the severity of the infection.
  • If the patient is receiving home care, follow daily by telephone call for 2 to 4 days; the patient may need frequent office visits.
PATIENT EDUCATION
  • American Academy of Pediatrics: http://www.aap.org
  • American Academy of Family Physicians: http://www.familydoctor.org
PROGNOSIS
  • Recovery time is variable. 40% can have symptoms at 14 days and 10% at 4 weeks.
  • Mortality statistics differ but probably <1%.
  • High-risk infants (bronchopulmonary dysplasia, congenital heart disease) may have a prolonged course.
REFERENCES
1. Ralston SL, Lieberthal AS, Meissner HC, et al. Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis. Pediatrics. 2015;136(4):782.
2. Zhang L, Mendoza-Sassi RA, Wainwright C, et al. Nebulised hypertonic saline solution for acute bronchiolitis in infants. Cochrane Database Syst Rev. 2013;(7):CD006458.
3. Øymar K, Skjerven HO, Mikalsen IB. Acute bronchiolitis in infants, a review. Scand J Trauma Resucs Emerg Med. 2014;22:23.
4. Pickering LK, Kimberlin DW, Long SS, eds. Red Book: 2012 Report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2012.
5. Liet JM, Ducruet T, Gupta V, et al. Heliox inhalation therapy for bronchiolitis in infants. Cochrane Database Syst Rev. 2015;(9):CD006915.
Additional Reading
  • Beggs S, Wong ZH, Kaul S, et al. High-flow nasal cannula therapy for infants with bronchiolitis. Cochrane Database Syst Rev. 2014;(1):CD009609.
  • Fernandes RM, Bialy LM, Vandermeer B, et al. Glucocorticoids for acute viral bronchiolitis in infants and young children. Cochrane Database Syst Rev. 2013;(6):CD004878.
  • García CG, Bhore R, Soriano-Fallas A, et al. Risk factors in children hospitalized with RSV bronchiolitis versus non-RSV bronchiolitis. Pediatrics. 2010;126(6):e1453-e1460.
Codes
ICD10
  • J21.9 Acute bronchiolitis, unspecified
  • J21.0 Acute bronchiolitis due to respiratory syncytial virus
  • J21.8 Acute bronchiolitis due to other specified organisms
Clinical Pearls
  • Bronchiolitis is the leading cause of hospitalizations in infants and children—especially <3 months of age.
  • Diagnosis is a clinical one.
  • Parental education and support is essential.
  • Nasal and upper airway suctioning mainstay of treatment