BRONCHIOLITIS

BRONCHIOLITIS - Dennis E. Hughes, DO
BASICS
DESCRIPTION
• Inflammation and obstruction of small airways and reactive airways. May be seasonal (winter and spring) and often occurs in epidemics
• Usual course: Insidious; acute; progressive
ALERT
Pediatric Considerations
Most common in infants
GENERAL PREVENTION
• 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, October-May, 15 mg/kg IM; used for respiratory syncytial virus prevention in high-risk patients
- 28-32 week gestation and 6 months old; once begun, continue through end of season regardless of age attained
- 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)
• 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 (1).
EPIDEMIOLOGY
• Leading cause of hospitalizations in infants and children.
• Predominant age: Newborn to 2 years (peak age 6 months). Neonates are not protected despite transfer of maternal antibody.
• Predominant sex: Male > Female
Incidence
21% in North America; 3% of children hospitalized with bronchiolitis. Increasing since 1980 (1).
RISK FACTORS
• Smoking
• Low birth weight
• Immunodeficiency
• Formula feeding (not breastfed)
• Contact with infected person
• Children in day care environment
• Heart-lung transplantation patient
• Adults: Exposure to toxic fumes, connective tissue disease
ETIOLOGY
• Respiratory syncytial virus (70%)
• Parainfluenza
• Adenovirus
• Rhinovirus
• Influenza virus
• Chlamydia
• Eye, nose, mouth inoculation
• Necrosis and lysis of epithelial cells and subsequent release of inflammatory mediators. This results in edema, mucus secretion, combined with necrotic debris, and loss of cilia, resulting in luminal obstruction.
ASSOCIATED CONDITIONS
• Common cold
• Conjunctivitis
• Pharyngitis
• Otitis media
• Diarrhea

DIAGNOSIS
SIGNS AND SYMPTOMS
• Anorexia
• Cough
• Cyanosis
• Apnea
• Fever
• Grunting
• Irritability
• Noisy breathing (due to rhinorrhea)
• Vomiting
Physical Exam
• Tachypnea
• Rhinorrhea
• Wheezing
• Retractions
TESTS
• Arterial O2 saturation by pulse oximetry (92% significant)
• Respiratory viral antigens (not usually necessary during RSV season because the disease is managed symptomatically)
• Urine culture is advised as there is a clinically relevant rate of UTI (1).
Sepsis work up not usually necessary if clinical picture is consistent with bronchiolitis
Imaging
Chest radiograph
• Patchy infiltrates
- Focal atelectasisright upper lobe common
- Air trapping
- Flattened diaphragm
- Increased anteroposterior diameter
- 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
• Asthma
• Vascular ring
• Foreign body
• Heart failure
• Bacterial pneumonia
• Gastroesophageal reflux
• Aspiration
• Cystic fibrosis
• Pertussis
• Croup
TREATMENT
• Most patients can be treated at home.
• Inpatient treatment is indicated for a patient with increased respiratory distress, cyanosis, and dehydration or inability to feed.
GENERAL MEASURES
• Most critical phase is the 1st 48-72 hours after onset. Treatment is usually symptomatic.
• Fluid at maintenance (after correcting for any dehydration); add for respiratory fluid loss.
• Mechanical ventilation in respiratory failure
• Isolation: Contact; hand washing most important
• Cardio-respiratory monitoring
Diet
• Frequent small feedings of clear liquids
• If hospitalized, a patient may require intravenous fluids.
Activity
• Avoid exposure to crowds, viral illness for 2 months
• Avoid smoke
MEDICATION (DRUGS)
First Line
• Oxygen
• Nebulized Albuterol (0.15 mg/kg) may be effective for acute symptoms; a trial of therapy is reasonable. No benefit noted in several high quality studies (1, 2)[B].
• Epinephrine aerosols (0.5 mL of 2.25% solution in 3 mL NS) also may be tried. Caution, because a "rebound phenomena" may occur (child is sent home and worsens: monitor for 2 hours). Benefit remains unproven (3)[B].
• Ribavirin
- Controversial (cost, unclear efficacy)
- Inhaled antiviral agent active against respiratory syncytial virus
- May be indicated in patients with underlying cardiopulmonary disease, young age (6 weeks), immunosuppressed (AIDS, organ transplant patients), or premature infants
- Nebulize via small-particle aerosol generator
- Pregnant women should not be exposed (1).
• Corticosteroids
- Oral dexamethasone (1mg/kg loading dose, then 0.6 mg/kg b.i.d. for 5 days) reduced subsequent hospitalization (4)[B].
- Nebulized dexamethasone (2-4 mg in 3 mL NS) may have anecdotal benefit; studies show mixed results (1).
Second Line
• Antibiotics only if secondary bacterial infection present (rare)
• Heliox therapy(70% helium-30% oxygen) maybe of benefit in moderate to severe bronchiolitis (5)[C].
FOLLOW-UP
DISPOSITION
Admission Criteria
• Respiratory rate >70/min with respiratory distress or apnea
• Ill or toxic appearance
• Underlying heart or respiratory condition
• Dehydrated or unable to feed
• Uncertain home care
PROGNOSIS
• 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.
COMPLICATIONS
• Bacterial superinfection
• Bronchiolitis obliterans
• Apnea
• Respiratory failure
• Death
• Increased incidence of reactive airway disease
PATIENT MONITORING
• If the patient is receiving home care, follow daily by telephone for 2-4 days; the patient may need frequent office visits.
• For a hospitalized patient, monitor as needed depending on the severity of the infection. Bronchiolitis can be associated with apnea. Hospitalization is usually only required if oxygen is a requirement.
REFERENCES
1. King VJ, et al. Pharmacologic treatment of bronchiolitis in infants and children: A systematic review. Arch Pediatr Adolesc Med 2004;158(2):127-137.
2. 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):818-824.
3. Mull cc, et al. A randomized trial of nebulized epinephrine vs albuterol in the emergency department of bronchiolitis. Arch Pediatr Adolesc Med 2004;158(2):113-118.
4. Schuh S, et al. Efficacy of oral dexamethasone in outpatients with acute bronchiolitis. J Ped 2002;140(1):27-32.
5. Martinon-Torres F, et al. Heliox therapy in infants with acute bronchiolitis. Pediatrics 2002;109(1):68-73.