Bronchiolitis The 5 Minute Pediatric Consult


	Bronchiolitis

Hakon Hakonarson

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

Acute lower respiratory illness that causes obstruction of the small conducting airways of the lung.

PATHOPHYSIOLOGY AND CAUSES

Respiratory synsytical virus (RSV) is the most common cause of this illness.
RSV is transmitted by:
- Direct contact with nasal secretions from an infected individual.
- Aerosol spread (less common).
RSV induces damage to the bronchial epithelium, resulting in inflammation of the smaller airways.
Leukocytes (predominantly lymphocytes) infiltrate the peribronchial epithelial tissue, causing airway edema.
Inflammation causes necrosis of the respiratory epithelium with replacement by nonciliated epithelial cells, which diminish the proximal movement of secretions to the larger airways and results in airway obstruction.
IgE-mediated hypersensitivity may play a role.
Other agents associated with bronchiolitis include:
- Parainfluenza viruses? Influenza A
- Adenovirus
- Rhinovirus
- Mycoplasma pneumoniae

EPIDEMIOLOGY

Seen in all geographic areas
Peaks during the winter and early spring
Most children infected in the first 3 years of life; 80% within the first 12 months
More common in infants with:
- Lower socioeconomic status
- Crowded living conditions
- Delayed immunizations
- Exposure to cigarette smoke
- Bottle-feeding versus breast-feeding
More serious the younger the child (6 months)
Rarely fatal in otherwise healthy infants
Approximately one-half of infants with bronchiolitis develop subsequent wheezing.

GENETICS

Genetic background is unclear.

Complications

Most serious/common complications:
- Pneumonia
- Respiratory failure
- Apnea
Highest risk of complications seen with:
- Congenital heart disease
- Bronchopulmonary dysplasia (BPD)
- Chronic lung disease
- Cystic fibrosis
- Prematurity
- Immunodeficiency

PROGNOSIS

For most infants: excellent, self-resolving disease
Death occurs rarely in infants and babies with no underlying disease (usually as a result of unrecognized apnea, respiratory failure, or superinfection)
Morbidity and mortality is considerable in patients with an underlying chronic disease.
40% to 50% of infants will have recurrent episodes of wheezing until 2 to 3 years of age:
- Some will develop asthma.
- Others have abnormal lung function later in childhood.

DIFFERENTIAL DIAGNOSIS

Pneumonia (viral or bacterial)
Asthma
Gastroesophageal reflux (GER)
Foreign body
Noxious agents (chemicals, fumes, toxins)

DATA GATHERING

HISTORY

Question: Rhinorrhea with thick nasal secretions?
Significance: Characteristic of disease

Question: Coughing?
Significance:

Initially hoarse cough for 3 to 5 days
Progresses to deep, wet cough of increased frequency

Question: Poor feeding?
Significance: Possible dehydration

Question: Low-grade fever?
Significance: Characteristic of disease

Question: Restlessness or lethargy?
Significance: May indicate low oxygen saturation

Question: Apnea (seen in younger patients)?
Significance: Impending failure

Question: Color change/cyanosis?
Significance: Impending failure

Question: Development of respiratory distress?
Significance: Impending failure

PHYSICAL EXAMINATION

PULMONARY EXAMINATION

Cough
Tachypnea
Accessory muscle retractions
Hyperresonance to percussion
High-pitched wheezing
Prolonged expiratory phase
Fine inspiratory crackles

HEENT EXAMINATION

Nasal flaring
Nasal congestion with thick, purulent secretions

OTHER FINDINGS

Low-grade fever
Tachycardia
Possible cyanosis of nail beds and oral mucosa
Liver and spleen typically pushed down by hyperinflated lungs

LABORATORY AIDS

BLOOD TESTS

Test: CBC with differential
Significance: Rarely helpful

Test: Pulse oximetry
Significance: To assess oxygenation

Test: Arterial blood gas
Significance: Useful for assessing:

Oxygenation
Evidence of respiratory failure acidosis with CO₂ retention

RAPID VIRAL IDENTIFICATION

Immunofluorescence or ELISA

VIRAL CULTURE

Test: Culture of nasopharynx
Significance: Should be done for all patients with negative rapid respiratory studies.

IMAGING

Chest radiography
Hyperinflation
Flattened diaphragms
Patchy or more extensive atelectasis
Possible collapse of a segment or a lobe
Diffuse interstitial infiltrates commonly seen

THERAPY

GENERAL MANAGEMENT

Most cases are mild and can be treated at home.
Only 1% to 5% of previously healthy children require hospitalization.
Hospitalization should be considered for infants and young children who:
- Were born prematurely.
- Appear ill or toxic.
- Are <3 months of age
- Have decreased oxygen saturation
- Have an underlying disease such as:
  - Bronchopulmonary dysplasia
  - Congenital heart disease
  - Chronic lung disease (i.e., cystic fibrosis)
  - Immunodeficiency

DRUGS

Supplemental Oxygen

Given to any patient with hypoxia

Bronchodilators

All infants with bronchiolitis with significant wheezing should receive a trial of at least one aerosolized b-adrenergic treatment to see if there is any relief of symptoms.
Infants with history of prior wheezing or a familial history of asthma are more likely to respond to a bronchodilator.
Theophylline not usually useful as a bronchodilator but should be considered if apnea is present (keep level 5–10 mg/mL).

Corticosteroids

Use in children with bronchiolitis has not been evaluated adequately.
Does not appear to be helpful

Antibiotics

Superimposed bacterial infection is rare.
Not usually indicated

Antiviral Agents (Ribavirin)

Ribavirin is a synthetic nucleoside with activity against several viruses, including RSV.
Use is controversial (beneficial effect most evident in the more severely ill patients).
Benefits
- Improves oxygenation
- Shortens duration of illness
- Shortens period of viral shedding
Indications
- Patients at increased risk for severe or complicated RSV infection
- Patients requiring mechanical ventilation
- Premature patients
- Patients <6 weeks of age
- Bronchopulmonary dysplasia
- Chronic lung disease
- Congenital heart disease
- Heart failure
- Pulmonary hypertension
- Patients with immunodeficiency
- Patients receiving chemotherapy
- Patients who have recently undergone transplantation
- Multiple congenital anomalies
- Neurological disorders
- Metabolical disorders
Dosing
- Delivered via small-particle aerosol generator.
- Dosage: 6 g in 300 mL sterile H₂O given over 12 to 20 hours for 3 to 7 days
- Precautions: pregnant women should avoid exposure due to possible teratogenic effects.

RSV Hyperimmunoglobulin (RSV-IVIG)

Recommended for premature infants and infants with chronic pulmonary disease (e.g., BPD)
Human monoclonal antibodies for intramuscular injection are currently under investigation with promising results to date
This therapy has not yet been approved by the FDA

Duration

Continue bronchodilators until oxygenation normalizes and/or bronchospasm resolves.
Ribavirin (if indicated) should be started as early in the illness as possible and continued for 5 days.

FOLLOW-UP

WHEN TO EXPECT IMPROVEMENT

Most infants improve within 3 to 5 days.
Those who need mechanical ventilation may have difficulties with extubation due to excessive secretions and atelectasis.

SIGNS TO WATCH FOR

Impending respiratory failure (increased work of breathing, retractions, hypoxemia, CO₂ retention, lethargy).
Sudden deterioration suggesting atelectasis due to mucous plugging.
Fatigue may occur in infants who have prolonged and extensive disease.
Fatigue will manifest with increased pCO₂ and worsening hypoxemia.

PITFALLS

Hypoxia is common, so always follow oxygen saturation.
Be aware of apnea.
Respiratory failure may have a sudden presentation
In cases of clinical bronchiolitis, causes of false-negative ELISA tests:
- Poor quality of sample
- Sample contamination
- Insufficient sample
- Non-RSV bronchiolitis

COMMON QUESTIONS AND ANSWERS

Q: How did my child get bronchiolitis?
A: RSV bronchiolitis is a common, seasonal, lower respiratory tract infection that is easily transmissible.

Q: Can my child become reinfected?
A: Children can become reinfected with RSV bronchiolitis, and infection can occur more than once during the same respiratory season.

Q: Do patients with bronchiolitis need to be isolated?
A: Hospitalized patients who are RSV-positive need to be isolated with other RSV-positive patients and from uninfected patients. Patients who are receiving ribavirin should be kept in isolation.

Q: Will my child develop asthma?
A: Significant numbers of infected children will develop recurrent wheezing. Some will end up with asthma.

ICD-9-CM 466.19

BIBLIOGRAPHY

American Academy of Pediatrics. 1994 red book: report of the Committee on Infectious Diseases. Elk Grove Village, IL: American Academy of Pediatrics, 1994:396–398, 570–575.

Holberg CJ, Wright AL, Martinez FD, et al. Risk factors for respiratory syncytial virus-associated lower respiratory illness in the first year of life. Am J Epidemiol 1991;133:1135–1151.

Shaw KN, Bell LM, Sherman NH. Outpatient assessment of infants with bronchiolitis. Am J Dis Child 1991;145:151–155.

Welliver JR, Welliver RC. Bronchiolitis. Pediatr Rev 1993;14:134–139.

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