Bronchiolitis: Clinical Features and Management
Bronchiolitis is a clinical diagnosis based on history and physical examination alone, requiring only supportive care with oxygen for persistent SpO2 <90% and hydration assessment—bronchodilators, corticosteroids, chest physiotherapy, and routine antibiotics should NOT be used. 1
Clinical Features
Bronchiolitis presents as a viral lower respiratory tract infection characterized by:
Pathophysiology: Acute inflammation, edema, and necrosis of small airway epithelial cells, with increased mucus production and bronchospasm 1
Typical presentation:
- Viral upper respiratory prodrome (rhinorrhea) followed by lower respiratory symptoms
- Cough, tachypnea, wheezing, and diffuse crackles
- Increased respiratory effort: grunting, nasal flaring, intercostal/subcostal retractions 2
- Variable course from transient apnea to progressive respiratory distress
Age group: Primarily affects infants 1 month to 2 years old, with peak incidence 1-6 months 3
Causative agent: Respiratory syncytial virus (RSV) accounts for 60-80% of cases 4
Risk Factors for Severe Disease
Clinicians must identify high-risk infants who require closer monitoring 1, 2:
- Age <12 weeks
- Prematurity (<35 weeks gestation)
- Hemodynamically significant congenital heart disease
- Chronic lung disease (bronchopulmonary dysplasia)
- Immunodeficiency
- Neuromuscular diseases
- In utero smoke exposure
Diagnosis
Diagnosis is purely clinical—do NOT routinely order laboratory tests, viral testing, or chest radiographs 1. These investigations do not change management and should be reserved only when alternative diagnoses are being considered.
Key Assessment Points
- Respiratory rate: Count over full 60 seconds (normal decreases from 41 at 0-3 months to 31 at 12-18 months) 2
- Hydration status: Assess feeding ability and fluid intake 1
- Mental status: Evaluate alertness and responsiveness
- Work of breathing: Observe for retractions, nasal flaring, grunting
- Oxygen saturation: Measure SpO2 to guide oxygen therapy
Important caveat: Upper airway obstruction contributes to work of breathing—suctioning and positioning may improve examination quality and reduce respiratory effort 2.
Management: The "Minimal Handling" Approach
What TO DO
1. Oxygen Therapy 1
- Indication: SpO2 persistently <90% in previously healthy infants
- Target: Maintain SpO2 ≥90%
- Discontinuation criteria: SpO2 ≥90% AND infant feeding well AND minimal respiratory distress
- Special populations: Infants with hemodynamically significant heart/lung disease and premature infants require close monitoring during oxygen weaning 1
- Monitoring: Continuous SpO2 monitoring is NOT routinely needed as clinical course improves 1
2. Hydration Assessment 1
- Strong recommendation: Assess hydration status and oral fluid intake
- Provide appropriate fluid support based on clinical assessment
3. Infection Control 1
- Hand decontamination: Most important preventive measure for nosocomial spread
- Use alcohol-based rubs before/after patient contact and after removing gloves
- Educate personnel and family members on hand hygiene
What NOT TO DO
1. Bronchodilators (Albuterol, Salbutamol) 1
- Do NOT use routinely
- Optional: A carefully monitored trial may be attempted, but continue ONLY if documented objective clinical improvement occurs
- Evidence note: Despite some meta-analyses suggesting potential outpatient benefits 5, the AAP guideline firmly recommends against routine use based on lack of clinically meaningful outcomes
2. Corticosteroids 1
- Do NOT use routinely
- No evidence of benefit in improving clinical course
3. Ribavirin 1
- Do NOT use routinely
4. Antibiotics 1
- Use ONLY when specific bacterial coinfection is documented
- Critical pitfall: Unnecessary antibiotic use significantly prolongs hospital stay without improving outcomes 3
5. Chest Physiotherapy 1
- Do NOT use routinely
- No evidence of benefit
Emerging Therapies (Insufficient Evidence)
Hypertonic saline: While some recent studies suggest potential benefit 6, 5, current high-quality evidence remains insufficient to recommend routine use 4. The 2014 AAP guideline deimplemented this therapy for outpatient settings.
Epinephrine: Commonly used in some countries 6, but evidence is sparse and not recommended routinely by AAP guidelines 5.
Prevention
1. Palivizumab Prophylaxis 1
- Consider for high-risk infants: prematurity <35 weeks or congenital heart disease
- Dosing: 15 mg/kg IM monthly for 5 doses, typically starting November/December
2. Environmental Measures 1
- Strong recommendation: Avoid passive smoke exposure
- Encourage breastfeeding to decrease lower respiratory tract disease risk
Common Pitfalls to Avoid
- Over-testing: Ordering chest X-rays, viral panels, or blood work in straightforward cases wastes resources and doesn't change management
- Antibiotic overuse: Using antibiotics without documented bacterial infection prolongs hospitalization 3
- Continuing ineffective bronchodilators: If a trial is attempted, discontinue immediately if no objective improvement
- Premature oxygen discontinuation: Ensure infant is feeding well with minimal distress, not just achieving SpO2 target
- Inadequate risk stratification: Failing to identify high-risk infants who need closer monitoring
The evidence strongly supports a less-is-more approach—supportive care with oxygen and hydration assessment remains the cornerstone of management, with active de-implementation of non-evidence-based interventions being a major quality improvement goal 7, 4.