Bronchiolitis in Pediatrics: A Clinical Algorithm
Pathophysiology
Bronchiolitis results from viral infection causing acute inflammation, edema, and necrosis of epithelial cells lining the small airways, combined with increased mucus production and bronchospasm. 1 The most common causative agent is respiratory syncytial virus (RSV), accounting for the majority of cases, with peak incidence between December and March. 1 Other viral pathogens include human metapneumovirus, influenza, adenovirus, and parainfluenza. 1
The pathophysiologic cascade begins when the virus is transmitted through respiratory droplets via direct contact with infected persons or self-inoculation from contaminated surfaces. 2 Once the virus enters the respiratory tract, it targets the bronchiolar epithelium, triggering an inflammatory response that leads to:
- Epithelial cell necrosis and sloughing into the airway lumen 1
- Submucosal edema that narrows the small airways 1
- Increased mucus secretion that further obstructs airflow 1
- Bronchospasm contributing to wheezing and air trapping 1
This combination of inflammation, mucus plugging, and bronchospasm creates the characteristic clinical picture of increased work of breathing, wheezing, and hypoxemia. 1 The small caliber of infant airways makes them particularly vulnerable to these obstructive changes, explaining why bronchiolitis predominantly affects children under 2 years of age. 1
Diagnostic Algorithm
Step 1: Clinical Diagnosis
Bronchiolitis is a clinical diagnosis based on history and physical examination alone—do NOT routinely order chest radiographs, viral testing, or laboratory studies. 3, 4, 5
Key diagnostic features include:
- Age: 1-24 months (guideline excludes neonates <1 month) 1
- Prodrome: 2-4 days of upper respiratory symptoms (fever, rhinorrhea, congestion) 2
- Progression: Development of lower respiratory tract symptoms including:
Step 2: Severity Assessment
Assess severity using these specific clinical parameters:
- Respiratory rate: Tachypnea ≥70 breaths/minute indicates increased severity risk 3
- Work of breathing: Look for nasal flaring, grunting, intercostal/subcostal retractions 3
- Oxygen saturation: SpO2 <90% indicates need for supplemental oxygen 3, 4
- Hydration status: Assess ability to take fluids orally 3
- Feeding difficulties: Respiratory rate >60-70 breaths/minute significantly increases aspiration risk 3
- Irritability: History of irritability correlates with higher severity 6
Step 3: Risk Stratification
Identify high-risk infants who require closer monitoring: 3, 4
- Age <12 weeks 3, 4
- History of prematurity (especially <29 weeks gestation) 3, 2
- Chronic lung disease/bronchopulmonary dysplasia 1, 3
- Hemodynamically significant congenital heart disease 3, 2
- Immunodeficiency 3, 4
- Birth weight <1500 grams 6
Step 4: When Diagnostic Testing IS Indicated
Avoid routine testing, but consider specific tests only in these situations:
Chest radiograph: Only if considering alternative diagnoses (e.g., foreign body aspiration, pneumothorax, congenital anomaly)—NOT for routine bronchiolitis 3, 5
- Pitfall: Approximately 25% of hospitalized infants have radiographic atelectasis or infiltrates often misinterpreted as bacterial infection 4
Bacterial workup: Only if specific signs of bacterial coinfection present (e.g., acute otitis media, documented bacterial pneumonia) 3, 4
Management Algorithm
Outpatient Management (Mild Cases)
Step 1: Supportive Care Only
The cornerstone of bronchiolitis management is supportive care alone—avoid all routine pharmacologic interventions. 4
- Hydration: Continue oral feeding if infant feeds well without respiratory compromise 3
- Nasal suctioning: Use gentle nasal suctioning only as needed for symptomatic relief 3, 4
- Avoid deep suctioning: Associated with longer hospital stays in infants 2-12 months 3
- Breastfeeding: Continue breastfeeding if possible—reduces hospitalization risk by 72% 3, 5
- Parent education: Symptoms (cough, congestion, wheezing) typically last 2-3 weeks, which is normal 3
Step 2: Admission Criteria
Admit to hospital if any of the following:
- SpO2 persistently <90% 3, 4
- Respiratory rate >60-70 breaths/minute with feeding difficulties 3
- Inability to maintain adequate oral hydration 3
- Significant respiratory distress (severe retractions, grunting) 3
- High-risk infant with any concerning features 3, 4
- Apnea 1
Inpatient Management (Moderate to Severe Cases)
Step 1: Oxygen Therapy
Administer supplemental oxygen ONLY if SpO2 persistently falls below 90%, and maintain SpO2 ≥90%. 3, 4, 5
- Use standard oxygen delivery methods 3
- Discontinue oxygen when: SpO2 ≥90%, infant feeding well, and minimal respiratory distress 3
- Avoid continuous pulse oximetry in stable infants: Serial clinical assessments are more important than continuous monitoring 3, 4
- Critical pitfall: Do NOT treat based solely on pulse oximetry readings without clinical correlation—transient desaturations occur in healthy infants 3, 4
Step 2: Hydration Management
- Oral feeding: Continue if respiratory rate <60-70 breaths/minute and infant feeding well 3
- IV/nasogastric fluids: Reserved for infants who cannot maintain adequate oral intake 3, 2
- Use isotonic fluids: Infants with bronchiolitis may develop SIADH and are at risk for hyponatremia with hypotonic fluids 3
Step 3: Airway Clearance
- Gentle nasal suctioning: May provide temporary relief 3
- Avoid chest physiotherapy: No evidence of benefit 3
What NOT to Do: Common Errors in Practice
Pharmacologic Interventions to AVOID
1. Bronchodilators
Do NOT use bronchodilators routinely for infants with bronchiolitis—they lack evidence of benefit. 3, 4, 5
- Exception: May consider a carefully monitored trial, but ONLY continue if documented positive clinical response 4
- Rationale: Multiple studies show no significant improvement in clinical outcomes 3, 4
2. Corticosteroids
Do NOT use corticosteroids routinely—meta-analyses show no significant benefit in length of stay or clinical scores. 3, 4, 5
3. Antibiotics
Do NOT use antibacterial medications unless specific indications of bacterial coinfection exist. 3, 4, 5
- Specific indications only: Acute otitis media or documented bacterial pneumonia 3, 4
- Critical point: Fever alone does NOT justify antibiotics—risk of serious bacterial infection is <1% 3, 4
4. Antiviral Agents (Ribavirin)
Do NOT use ribavirin routinely. 4
- Rare exception: May consider in highly selected situations (documented RSV with severe disease in immunocompromised patients) 4
Diagnostic Testing to AVOID
Do NOT routinely order: 3, 4, 5
- Chest radiographs (unless considering alternative diagnosis)
- Viral testing (RSV or other viral panels)
- Complete blood counts
- Blood cultures
- C-reactive protein or procalcitonin
Rationale: Bronchiolitis is a clinical diagnosis, and these tests do not change management in typical cases. 3, 5
Monitoring Pitfalls to AVOID
- Do NOT use continuous pulse oximetry in stable infants: Leads to less careful clinical monitoring and unnecessary interventions for transient desaturations 3, 4
- Do NOT overlook feeding difficulties: Aspiration risk increases significantly when respiratory rate exceeds 60-70 breaths/minute 3, 4
Prevention Strategies
Primary Prevention
1. Infection Control
- Avoid tobacco smoke exposure: Significantly increases severity and hospitalization risk 3, 5
- Limit visitor exposure during respiratory virus season: Helps prevent RSV transmission 3
- Hand hygiene: RSV transmitted through contact with respiratory droplets 2
2. Breastfeeding
Promote exclusive breastfeeding—reduces hospitalization risk by 72%. 3, 5
- Non-exclusive breastfeeding and early bottle feeding are significant risk factors for bronchiolitis severity 6
Secondary Prevention (Immunoprophylaxis)
Palivizumab (RSV prophylaxis) for high-risk infants: 5, 2
Indications:
- Infants born before 29 weeks gestation 5, 2
- Infants with chronic lung disease of prematurity 5, 2
- Infants and children with hemodynamically significant congenital heart disease 5, 2
Dosing:
- 15 mg/kg IM monthly 5
- 5 monthly doses starting November/December 5
- Goal: Reduce risk of hospitalization due to RSV infection 5
Special Considerations
High-Risk Populations
Infants <12 weeks require particularly close monitoring: 3, 4
- May have abnormal baseline oxygenation 3
- Higher risk of apnea 1
- More likely to develop severe disease 3, 7
Discharge Readiness
Criteria for safe discharge: 3
- SpO2 ≥90% on room air
- Feeding well without respiratory compromise
- Minimal respiratory distress
- Reliable follow-up arranged
- Parents educated on warning signs
Post-Bronchiolitis Management
For children with chronic cough post-bronchiolitis: 4
- Manage according to pediatric chronic cough guidelines
- Consider 2 weeks of antibiotics targeted to common respiratory bacteria for wet/productive cough without specific cough pointers 4
Long-term sequelae: 1
- Infants hospitalized with bronchiolitis are more likely to have recurrent wheezing as older children 1
- This guideline does not address long-term management of recurrent wheezing 1
Key Takeaways for Clinical Practice
The evidence overwhelmingly supports a "less is more" approach to bronchiolitis management. 3, 4, 5 The most common errors in practice involve:
- Over-testing: Ordering unnecessary chest radiographs, viral panels, and laboratory studies 3, 5
- Over-treating: Using bronchodilators, corticosteroids, and antibiotics without evidence of benefit 3, 4, 5
- Over-monitoring: Continuous pulse oximetry in stable infants leading to unnecessary interventions 3, 4
- Under-recognizing feeding difficulties: Missing the critical threshold of respiratory rate >60-70 breaths/minute 3
Focus clinical efforts on: 3, 4
- Accurate clinical diagnosis without routine testing
- Appropriate oxygen supplementation (only if SpO2 <90%)
- Adequate hydration support
- Serial clinical assessments rather than continuous monitoring
- Parent education on expected disease course and warning signs