Bronchiolitis – Causes, Symptoms, Diagnosis, Treatment and Ongoing care



  • Inflammation and obstruction of small airways and reactive airways generally affecting infants and young children
  • May be seasonal (winter and spring) and often occurs in epidemics
  • Usual course: Insidious, acute, progressive
  • Leading cause of hospitalizations in infants and children
  • Predominant age: Newborn–2 years (peak age <6 months). Neonates are not protected despite transfer of maternal antibody.
  • Predominant sex: Male > Female



  • 21% in North America
  • 18.8% (90,000 annually) of all pediatric hospitalizations (excluding live births) in children <2 years of age
  • Incidence increasing since 1980

Risk Factors

  • Smoking exposure
  • Low birth weight
  • Immunodeficiency
  • Formula feeding (not breastfed)
  • Contact with infected person (primary mode of spread)
  • Children in daycare environment
  • Heart-lung transplantation patient
  • Adults: Exposure to toxic fumes, connective tissue disease

General Prevention

  • Handwashing
  • Contact isolation of infected babies
  • Persons with colds should keep contacts with infants to a minimum
  • Palivizumab (Synagis), a monoclonal product, administered monthly, October–May, 15 mg/kg IM; used for respiratory syncytial virus prevention in high-risk patients (1):
    • 32–35-week gestation and <3 months old at the start of RSV season with at least 1 risk factor: Either attending daycare or with a sibling <5 years old at home
    • 28–32-week gestation and <6 months old
    • <28 weeks gestation and <12 months old
    • Moderately severe bronchopulmonary dysplasia and up to 2 years old
    • Hemodynamically significant congenital heart disease (until age 6 months)
    • Once begun, continue through end of season regardless of age attained
  • Respiratory syncytial virus immune globulin, a human blood product, can also be used in at-risk patients. Monthly infusions of 750 mg/kg, October–May.


  • Infection results in necrosis and lysis of epithelial cells and subsequent release of inflammatory mediators.
  • Edema and mucus secretion that, combined with accumulating necrotic debris and loss of cilia clearance, results in luminal obstruction.
  • Ventilation-perfusion mismatching resulting in hypoxia
  • Air trapping is due to dynamic airways narrowing during expiration, which increases work of breathing.


Respiratory syncytial virus accounts for 70–85% of all cases, but parainfluenza virus, adenovirus, rhinovirus, influenza virus, Mycoplasma pneumoniae, and Chlamydia pneumoniae have all been implicated.

Pediatric Considerations

Prior infection does not seem to confer subsequent immunity.

Commonly Associated Conditions

  • Upper respiratory congestion
  • Conjunctivitis
  • Pharyngitis
  • Otitis media
  • Diarrhea

Bronchiolitis, Human respiratory syncytial virus, Palivizumab, Vaccine, Immune system, connective tissue disease, immune globulin, virus prevention, low birth weight, infants and young children,


Consensus is that history and physical examination should be the basis for the diagnosis of bronchiolitis (2).


  • Irritability
  • Anorexia
  • Fever
  • Noisy breathing (due to rhinorrhea)
  • Cough
  • Grunting
  • Cyanosis
  • Apnea
  • Vomiting

Physical Exam

  • Tachypnea
  • Retractions
  • Rhinorrhea
  • Wheezing
  • Upper respiratory findings: Pharyngitis, conjunctivitis, otitis

Diagnostic Tests & Interpretation

Routine laboratory and other ancillary testing not warranted


Initial lab tests

  • Arterial oxygen saturation by pulse oximetry (<94% significant)
  • Rapid respiratory viral antigen testing (not usually necessary during respiratory syncytial virus [RSV] season because the disease is managed symptomatically, but may be useful for epidemiologic, hospital cohorting purposes, or in the very young to reduce unnecessary other workup):
    • Sensitivity 87–91%; specificity 96–100% (2)


Initial approach

Chest x-ray (CXR):

  • Increased anteroposterior diameter
  • Flattened diaphragm
  • Air trapping
  • Patchy infiltrates
  • Focal atelectasis: Right upper lobe common
  • Peribronchial cuffing

Pathological Findings

  • Abundant mucous exudate
  • Mucosal: Hyperemia, edema
  • Submucosal lymphocytic infiltrate, monocytic infiltrate, plasmacytic infiltrate
  • Small airway debris, fibrin, inflammatory exudate, fibrosis
  • Peribronchiolar mononuclear infiltrate

Differential Diagnosis

  • Other pulmonary infections such as pertussis, croup, or bacterial pneumonia
  • Aspiration
  • Vascular ring
  • Foreign body
  • Asthma
  • Heart failure
  • Gastroesophageal reflux
  • Cystic fibrosis


Mainstay of therapy is supportive to prevent hypoxia and dehydration.


First Line

  • Oxygen
  • Nebulized albuterol (0.15 mg/kg) is often tried for acute symptoms; a trial of therapy may be reasonable in the presence of a bronchospastic component, but no benefit noted in several high-quality studies (3)[B].
  • Epinephrine aerosols (0.5 mL of 2.25% solution in 3 mL NS) also may be tried. Benefit remains unproved, but some studies support short-term improvement in outpatient settings (4,5)[B].
  • Corticosteroids:
    • Oral dexamethasone (1 mg/kg loading dose, then 0.6 mg/kg b.i.d. for 5 days) reduced subsequent hospitalization. A recent multiple-center trial found no difference in admission rates or respiratory assessment scores in children treated with 1 mg/kg dexamethasone (6)[B].
    • Nebulized dexamethasone (2–4 mg in 3 mL NS) may have anecdotal benefit; studies show mixed results.

Second Line

  • Antibiotics only if secondary bacterial infection present (rare) (7)[B]
  • Heliox therapy (70% helium -30% oxygen) may be of benefit early in moderate-to-severe bronchiolitis to reduce amount of respiratory distress (8).
  • Ribavirin (palivizumab):
    • Updated AAP guidelines for use (for prevention in high-risk children)
    • Inhaled antiviral agent active against RSV
    • Nebulize via small-particle aerosol generator.
    • Pregnant women should not be exposed.

Additional Treatment

  • Nebulized hypertonic (3%) saline has recently been studied and may decease LOS in hospitalized patients (5).
  • Positive pressure ventilation (PPV) in the form of CPAP can be used in cases of respiratory failure. There is limited clinical evidence other than observational studies (5).
  • Leukotriene receptor antagonists currently show no sustained benefit (5).

In-Patient Considerations

Support's development and hosting

Bronchiolitis can be associated with apnea.

Initial Stabilization

Supplemental oxygen for pulse oximetry <94% on room air

Admission Criteria

  • Respiratory rate >45/min with respiratory distress or apnea
  • Hypoxia is common; evidence-based cutoff requiring admission is not available (only “D” level-expert opinion), so clinical criteria are more helpful.
  • Ill or toxic appearance
  • Underlying heart, respiratory condition, or immune suppression
  • High risk for apnea (<30 days of age, preterm birth [<37 weeks]) (7)[B]
  • Dehydrated or unable to feed
  • Uncertain home care
  • Use of Respiratory Distress Assessment Instrument can aid in determining admission vs discharge. Scoring based on quantification and quality of wheezes, retractions, and respiratory rate (6).

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)

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

  • Hospitalization is usually only required 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 for 2–4 days; the patient may need frequent office visits.

Patient Education

  • American Academy of Pediatrics:
  • American Academy of Family Physicians:


  • In most cases, recovery is complete within 7–14 days.
  • Mortality statistics differ, but probably <1%.
  • High-risk infants (bronchopulmonary dysplasia, congenital heart disease) may have a prolonged course.


  • Bacterial superinfection
  • Bronchiolitis obliterans
  • Apnea
  • Respiratory failure
  • Death
  • Increased incidence of development of reactive airway disease (asthma)


1. REDBOOK: Report of the Committee on Infectious Disease. American Academy of Pediatrics. 2009

2. Cincinnati Children’s Hospital Medical Center. Evidence-based clinical practice guideline for medical management of bronchiolitis in children less than 1 year of age presenting with a first time episode. Cincinnati (OH): Cincinnati Children’s Hospital Medical Center; 2006. May. 13p (85 references)

3. Patel H, et al. A randomized, controlled trial of the effectiveness of nebulized therapy with epinephrine compared with albuterol and saline in infants hospitalized for acute viral bronchiolitis. J Ped.2002;141(6):818–24.

4. Mull CC, Scarfone RJ, Ferri LR, et al. A randomized trial of nebulized epinephrine vs albuterol in the emergency department treatment of bronchiolitis. Arch Pediatr Adolesc Med. 2004;158:113–8.

5. Petruzella FD, Gorelick MH et al. Current therapies in bronchiolitis. Pediatr Emerg Care. 2010;26:302–7.

6. Corneli HM, Zorc JJ, Majahan P, et al. A multicenter, randomized, controlled trial of dexamethasone for bronchiolitis. N Engl J Med. 2007;357:331–9.

7. Spurling GKP, et al. Antibiotics for bronchiolitis in children. Cochrane Database Syst Rev. 2007;1:CD005189. DOI:10.1002/14651859, CD005189.pub2.

8. Liet JM, Ducruet T, Gupta V, Cambonie G et al. Heliox inhalation therapy for bronchiolitis in infants. Cochrane Database Syst Rev. 2010;4:CD006915.

Additional Reading

Bush A, Thomson AH. Acute bronchiolitis. BMJ. 2007;335:1037–41.

Everard ML. Acute bronchiolitis and croup. Pediatr Clin North Am. 2009;56:119–33, x–xi.

Worrall G. Bronchiolitis. Can Fam Physician. 2008;54:742–3.

Yanney M, Vyas H. The treatment of bronchiolitis. Arch Dis Child. 2008;93:793–8.



466.19 Acute bronchiolitis due to other infectious organisms


4120002 Bronchiolitis (disorder)

Clinical Pearls

  • Bronchiolitis is the leading cause of hospitalizations in infants and children.
  • Treatment is primarily supportive.
  • Antibiotics not helpful in the majority of cases
  • Parental education of expected course of illness important
  • Be aware of new Synagis treatment guidelines for premature infants.

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