Bronchiolitis

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

Laboratory

• 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

Imaging

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

Diagnostic Procedures

N/A

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

Activity

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

Diet

• 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

Miscellaneous

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

Abbreviations

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