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Description of Medical Condition

Inflammation of the bronchioles, usually seen in young children, occasionally in high-risk adults. May be seasonal (winter and spring) and often occurs in epidemics. Usual course: insidious; acute; progressive.

System(s) affected: Pulmonary

Genetics: N/A

Incidence/Prevalence in USA: Medical care provided to 1000-1500/100,000 annually. Estimated incidence is higher. Annual winter-spring epidemics.

Predominant age: newborn-2 years (peak age 2-6 months)

Predominant sex: Male > Female

Medical Symptoms and Signs of Disease

  • Anorexia
  • Cough
  • Cyanosis
  • Expiratory wheezing
  • Apnea
  • Fever
  • Grunting
  • Inspiratory crackles
  • Intercostal retractions
  • Irritability
  • Noisy breathing
  • Otitis media
  • Pharyngitis
  • Tachycardia
  • Tachypnea
  • Vomiting


What Causes Disease?

  • Respiratory syncytial virus — most prevalent
  • Parainfluenza
  • Adenovirus
  • Rhinovirus
  • Influenza virus
  • Chlamydia
  • Eye, nose, mouth inoculation
  • Exposure to adult with URI
  • Day care exposure (significant)
  • Idiopathic (many adult cases)

Risk Factors

  • Contact with infected person
  • Children in day care environment
  • Heart-lung transplantation patient
  • Adults — exposure to toxic fumes, connective tissue disease

Diagnosis of Disease

Differential Diagnosis

  • Asthma
  • Vascular ring
  • Lobar emphysema
  • Foreign body
  • Heart disease
  • Pneumonia
  • Reflux
  • Aspiration
  • Cystic fibrosis


  • Arterial blood gas — hypoxemia, hypercarbia, acidemia
  • Respiratory viral culture
  • Respiratory viral antigens

Drugs that may alter lab results: N/A

Disorders that may alter lab results: N/A

Pathological Findings

  • Abundant mucous exudate
  • Mucosal — hyperemia, edema
  • Submucosal lymphocyte infiltrate, monocytic infiltrate, plasmacytic infiltrate
  • Small airway debris, fibrin, inflammatory exudate. fibrosis
  • Peribronchiolar mononuclear infiltrate

Special Tests

Infant pulmonary function studies — research tool


  • Chest x-ray
  • Focal atelectasis — RUL common
  • Air trapping
  • Flattened diaphragm
  • Increased anteroposterior diameter
  • Peribronchial cuffing

Diagnostic Procedures


Treatment (Medical Therapy)

Appropriate Health Care

  • Most patients can be treated at home
  • Inpatient indicated for patient with increased respiratory distress, cyanosis, and dehydration or inability to feed

General Measures

  • Most critical phase is first 48-72 hours after onset. Treatment is usually symptomatic.
  • Fluid at maintenance
  • Mechanical ventilation in respiratory failure
  • Isolation: contact; handwashing most important
  • Antiviral agents for selected high-risk patients
  • Cardio-respiratory monitoring
  • Inhaled bronchodilators are commonly used, although efficacy has been hard to demonstrate in controlled studies
  • Steroids may not change course — except in patients with reactive airway disease


  • Avoid exposure to crowds, viral illness for 2 months
  • Avoid smoke


  • Frequent small feedings of clear liquids
  • If hospitalized, may require intravenous fluids

Patient Education

  • Griffith: Instructions for Patients; Philadelphia, Elsevier
  • American Academy of Pediatrics; website www.aap.org


Medications (Drugs, Medicines)

Drug(s) of Choice

  • Oxygen
  • Albuterol: may be effective for acute symptoms
  • Epinephrine aerosols may be of more benefit
  • Ribavirin: For infants and children, an inhaled antiviral agent active against RSV, may be indicated in patients with underlying cardio-pulmonary disease, young age (< 6 weeks), or with severe RSV (elevated pC02; require mechanical ventilation — use with caution via ventilator). Nebulize via small particle aerosol generator (SPAG). Use of ribavirin has decreased in recent years, secondary to lack of significant clinical efficacy.

Contraindications: Refer to manufacturer’s literature

Precautions: None

Significant possible interactions: None

Alternative Drugs

  • Antibiotics only if secondary bacterial infection present (rare)
  • Corticosteroids do not change course, unless infant has reactive airway disease. In adults corticosteroids may be helpful.

Patient Monitoring

  • If patient is receiving home care, follow daily by telephone for 2-4 days
  • For hospitalized patient, monitor as needed depending on severity of infection. Bronchiolitis can be associated with apnea.

Prevention / Avoidance

  • Hand washing
  • Contact isolation of infected babies
  • Persons with colds should keep contacts with infants to a minimum
  • Palivizumab (Synagis), a monoclonal product, administered monthly, November through March, 15 mg/kg IM. Available in single use vials of 100mg and 50mg. Used for RSV prevention in high risk patients:
    •  28-32 weeks gestation and less than 6 months old in November
    •  Less than 28 weeks gestation and less than 12 months old
    •  Moderately severe BPD and up to two years old
    •  Hemodynamically significant congenital heart disease (until age 6 months)
  • RSV immune globulin, a human blood product, can also be used in at-risk patients. Monthly infusions of 750 mg/kg, November through March, in a controlled setting. Avoid fluid overload. Vial is 50 mg/mL; infuse at 1.5-6 mL/kg/hr; monitor oximeter and vital signs.
  • Both of these medications are quite expensive.

Possible Complications

  • Bacterial superinfection
  • Bronchiolitis obliterans
  • Apnea
  • Respiratory failure
  • Death
  • Increased incidence of RAD

Expected Course / Prognosis

  • In most cases, recovery is complete within 7-10 days
  • Mortality statistics differ, but probably under 1%
  • High-risk infants (BPD, CHD) may have prolonged course


Associated Conditions

  • Common cold
  • Conjunctivitis
  • Pharyngitis
  • Otitis media
  • Diarrhea

Age-Related Factors

Pediatric: Most common in infants

Geriatric: N/A

Pregnancy: N/A

International Classification of Diseases

466.11 Acute bronchiolitis due to respiratory syncytial virus

466.19 Acute bronchiolitis due to other infectious organisms


BPD = bronchopulmonary dysplasia CHD = congenital heart disease RAD = reactive airway disease SPAG = small particle aerosol generator

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