Overview
Bronchiolitis
Quick Reference
Critical Alerts
- Supportive care is the mainstay: No evidence for routine bronchodilators, steroids, or antibiotics
- Apnea risk in young infants: <6 weeks, premature, or history of apnea
- Nasal suctioning before feeds: Infants are obligate nasal breathers
- Hydration is critical: Oral or IV as needed
- Avoid unnecessary interventions: Guidelines now advise against many treatments
- High-flow nasal cannula can help: For moderate-severe respiratory distress
Key Diagnostics
| Test | Finding | Significance |
|---|---|---|
| Pulse oximetry | SpO2 <90-92% | Indication for O2 supplementation |
| Clinical assessment | RR, WOB, feeding ability | Drives management |
| Respiratory viral panel | RSV, other viruses | Cohorting, prognosis (not required for diagnosis) |
| CXR | Not routinely recommended | Only if diagnostic uncertainty |
Emergency Treatments
| Intervention | Details | Notes |
|---|---|---|
| Nasal suctioning | Gentle bulb suction or mechanical | Before feeds, when congested |
| Supplemental O2 | Low-flow NC; HFNC for moderate-severe | Goal SpO2 ≥90% |
| IV or NG fluids | If unable to maintain hydration orally | Usually 2/3 maintenance |
| High-flow nasal cannula | For increased WOB | May reduce need for ICU |
| Bronchodilators | NOT routinely recommended | Trial ONLY if significant wheezing |
| Corticosteroids | NOT recommended | No benefit in bronchiolitis |
Definition
Overview
Bronchiolitis is an acute viral lower respiratory tract infection primarily affecting infants and children under 2 years of age, most commonly caused by respiratory syncytial virus (RSV). It is characterized by inflammation and obstruction of small airways (bronchioles), leading to cough, wheeze, and respiratory distress. Management is predominantly supportive.
Classification by Severity
| Severity | Features |
|---|---|
| Mild | Normal RR, minimal or no retractions, feeding well, SpO2 ≥95% |
| Moderate | Elevated RR, mild-moderate retractions, some feeding difficulty, SpO2 90-94% |
| Severe | Marked tachypnea, significant retractions, poor feeding/dehydration, SpO2 <90%, apnea |
Epidemiology
- Peak age: 2-6 months
- Seasonality: November to March (Northern Hemisphere)
- Hospitalization rate: 2-3% of all infants <1 year
- ED visits: ~1.5 million/year in US
- Mortality: Rare in developed countries (<0.5%); higher in developing countries and high-risk infants
Etiology
Causative Viruses:
| Virus | Percentage |
|---|---|
| RSV | 50-80% |
| Rhinovirus | 10-30% |
| Parainfluenza | 5-10% |
| Human metapneumovirus | 5-10% |
| Influenza | 5% |
| Adenovirus | 5% |
| Coronavirus | 2-5% |
Risk Factors for Severe Disease:
| Risk Factor | Comment |
|---|---|
| Age <6 weeks | Higher apnea risk |
| Prematurity (<37 weeks) | Less developed airways |
| Congenital heart disease | Especially cyanotic or with pulmonary HTN |
| Chronic lung disease (BPD) | Baseline respiratory compromise |
| Immunodeficiency | T-cell defects, chemotherapy |
| Neuromuscular disease | Impaired respiratory effort |
| Down syndrome | Multiple risk factors |
| Trisomy 21, other syndromes | Airway abnormalities |
Pathophysiology
Mechanism of Disease
- Viral inoculation: Contact or droplet transmission
- Epithelial infection: Ciliated epithelial cells of bronchioles
- Inflammation: Edema, peribronchiolar inflammation
- Mucus hypersecretion: Airway plugging
- Cell necrosis and sloughing: Debris obstructs airway
- Airflow obstruction: Wheeze, hyperinflation, atelectasis
- V/Q mismatch: Hypoxemia
Why Infants Are More Affected
- Smaller airway diameter → greater resistance with any narrowing
- Less developed collateral ventilation
- Compliant chest wall → retractions
- Obligate nasal breathers
Disease Course
- Incubation: 2-8 days
- Prodrome: 1-3 days of URI symptoms
- Peak illness: Days 3-5 (respiratory symptoms)
- Resolution: 1-2 weeks (cough may persist longer)
Clinical Presentation
Symptoms
Prodrome (1-3 days):
Progressive Illness:
History
Key Questions:
Physical Examination
Vital Signs:
| Finding | Interpretation |
|---|---|
| Tachypnea | Common; RR >0 in infants is concerning |
| SpO2 <92% | Moderate-severe; needs O2 |
| Tachycardia | Fever, increased WOB |
| Fever | Usually low-grade; high fever consider bacterial superinfection |
Respiratory Examination:
| Finding | Significance |
|---|---|
| Nasal flaring | Increased WOB |
| Retractions (subcostal, intercostal) | Moderate-severe airway obstruction |
| Grunting | Severe; attempting to maintain PEEP |
| Wheezing (expiratory) | Bronchiolar obstruction |
| Crackles/rales | Common in bronchiolitis |
| Prolonged expiratory phase | Air trapping |
| Hypoxia | Concerning sign |
General:
Rhinorrhea
Common presentation.
Congestion
Common presentation.
Low-grade fever
Common presentation.
Decreased appetite
Common presentation.
Red Flags
Signs of Severe Disease
| Finding | Concern | Action |
|---|---|---|
| Apnea | Life-threatening | Admit, continuous monitoring |
| SpO2 <90% despite O2 | Severe hypoxemia | HFNC or escalate |
| Marked retractions, grunting | Respiratory distress | Consider HFNC, PICU |
| Lethargy, poor responsiveness | Impending failure | Urgent reassessment |
| Inability to feed | Dehydration, fatigue | IV fluids, admit |
| Cyanosis | Severe hypoxemia | O2, escalate care |
| RR >0 in infant | Significant distress | Admit, close monitoring |
High-Risk Infants
- Age <6 weeks
- Prematurity <32 weeks
- Hemodynamically significant congenital heart disease
- Chronic lung disease/BPD
- Immunodeficiency
- Neuromuscular disease
Differential Diagnosis
Other Causes of Infant Respiratory Distress
| Diagnosis | Features |
|---|---|
| Viral-induced wheeze / early asthma | Recurrent episodes, older infant |
| Pertussis | Paroxysmal cough, post-tussive emesis, apnea |
| Pneumonia (bacterial) | Focal findings, higher fever |
| Foreign body aspiration | Sudden onset, older infant/toddler |
| Congestive heart failure | Murmur, hepatomegaly, edema |
| Congenital airway anomaly | Tracheomalacia, vascular ring |
| Sepsis | Ill-appearing, variable respiratory findings |
| Croup | Barky cough, stridor, older infant |
| Gastroesophageal reflux | Feeding-related symptoms |
Diagnostic Approach
Clinical Diagnosis
- Bronchiolitis is a clinical diagnosis
- History + physical exam sufficient in typical presentation
- Routine testing is not recommended (AAP Guidelines 2014)
Testing (If Indicated)
| Test | Indication |
|---|---|
| Pulse oximetry | All patients; essential for severity |
| Viral testing (RSV, panel) | Cohorting, prognostication; not required for diagnosis |
| CXR | Atypical presentation, suspected pneumonia, ICU admission |
| Blood cultures, CBC | Fever in young infant, concern for bacterial infection |
| Electrolytes | If IV fluids needed, signs of dehydration |
| Blood gas | Severe distress, impending failure |
CXR Findings (When done):
- Hyperinflation
- Peribronchial thickening
- Atelectasis
- Patchy infiltrates
Treatment
Principles of Management
- Supportive care: The cornerstone
- Ensure oxygenation: SpO2 goal ≥90%
- Maintain hydration: Oral, NG, or IV
- Nasal suctioning: Before feeds
- Avoid unnecessary interventions: No antibiotics, steroids, or routine bronchodilators
Nasal Suctioning
Technique:
- Gentle bulb suction or mechanical suction
- Before feeds and when visibly congested
- Avoid deep or excessive suctioning (edema, vagal response)
Saline drops: May loosen secretions, but no proven benefit beyond comfort
Oxygen Therapy
Indications: SpO2 <90% (some guidelines say <92%)
| Method | Details |
|---|---|
| Low-flow nasal cannula | 0.5-2 L/min; for mild hypoxia |
| High-flow nasal cannula (HFNC) | 1-2 L/kg/min (max 8-10 L/min for infants); for moderate-severe distress |
HFNC Benefits:
- Provides PEEP-like effect
- Reduces work of breathing
- Reduces need for intubation/ICU in some settings
Weaning O2: When sustained SpO2 ≥90-94% on room air
Hydration
| Status | Intervention |
|---|---|
| Feeding well | Continue oral feeds; smaller, more frequent |
| Mild difficulty | Offer oral; consider NG if not taking adequate volumes |
| Moderate-severe | IV fluids (D5 1/2NS or isotonic at 2/3 maintenance) |
Bronchodilators (NOT Routinely Recommended)
AAP 2014 Guidelines: Should NOT administer albuterol or salbutamol routinely
When to Consider:
- Strong family history of asthma
- Older infant with recurrent wheezing
- Significant wheezing on exam (trial, assess response)
If Trial:
- Give one dose of albuterol (2.5 mg nebulized)
- Assess clinical response
- Continue ONLY if clear improvement
Corticosteroids (NOT Recommended)
- No proven benefit in bronchiolitis
- Do not reduce hospital LOS, need for O2, or admission
- Avoid routine use
Hypertonic Saline (Limited Role)
- 3% saline nebulized
- May reduce LOS in inpatients (modest effect)
- Not recommended for ED use or outpatients
Antibiotics (NOT Indicated Unless Bacterial Infection)
Bronchiolitis is viral:
- Antibiotics provide no benefit
- Use only if documented concurrent bacterial infection (UTI, AOM, pneumonia)
Chest Physiotherapy
- NOT recommended: No benefit, may increase distress
Palivizumab (Synagis)
Prevention, Not Treatment:
- RSV immunoprophylaxis for high-risk infants
- Given monthly during RSV season
- Does not treat active infection
Disposition
Discharge Criteria
- SpO2 ≥90-94% on room air for sustained period
- Adequate oral intake (>50% usual)
- No significant respiratory distress (breathing comfortably)
- Caregivers educated and confident
- Follow-up arranged
- Access to care if worsening
Admission Criteria
- SpO2 <90% on room air (or <92% in high-risk)
- Significant respiratory distress (moderate-severe retractions)
- Apnea
- Dehydration or inability to feed orally
- High-risk infant
- Concern for social situation or ability to return
ICU Admission Criteria
- Apnea requiring intervention
- Severe respiratory distress despite HFNC
- Impending respiratory failure
- Need for non-invasive or invasive ventilation
Follow-Up
| Situation | Follow-Up |
|---|---|
| Discharged mild bronchiolitis | PCP in 24-48 hours |
| High-risk infant | Within 24 hours |
| Hospitalized | PCP within 1 week |
Patient Education
Condition Explanation (For Parents)
- "Bronchiolitis is a common viral lung infection in young children that causes the small airways to become inflamed and filled with mucus."
- "It usually gets worse for the first few days before it gets better."
- "There is no medicine that cures it—we support your baby while the infection runs its course."
- "Suctioning the nose and keeping your baby hydrated are the most important things you can do at home."
Home Care Instructions
- Gentle nasal suctioning before feeds
- Smaller, more frequent feeds
- Keep baby's head slightly elevated
- Use saline drops before suctioning
- Avoid smoke and irritants
Warning Signs (Return Immediately)
- Breathing very fast or struggling to breathe
- Pauses in breathing (apnea)
- Lips or tongue turning blue
- Unable to feed or no wet diapers
- Very sleepy, difficult to rouse
- Worsening symptoms despite supportive care
Expected Course
- Peak of illness: Days 3-5
- Improvement: Days 5-7
- Cough may persist 2-4 weeks
- Future wheezing episodes may occur
Special Populations
Preterm Infants
- Higher risk of severe disease
- Lower threshold for admission
- May be eligible for palivizumab prophylaxis
- Apnea risk increased
Infants with CHD or BPD
- Higher risk of respiratory decompensation
- Lower oxygen reserve
- Early escalation of care
- Often require admission
Age <6 Weeks
- Highest risk for apnea
- Requires close monitoring
- Consider admission for most cases
Immunocompromised
- Prolonged viral shedding
- Higher risk of severe/prolonged illness
- May need antiviral therapy (ribavirin—rarely used)
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| Pulse oximetry documented | 100% | Severity assessment |
| Avoidance of routine bronchodilators | >0% | Guideline adherence |
| Avoidance of routine steroids | >5% | Guideline adherence |
| Avoidance of routine antibiotics | >5% | Appropriate use |
| Avoidance of routine CXR | >0% | Reduce unnecessary testing |
| Caregiver education | 100% | Proper home care |
Documentation Requirements
- Vital signs including SpO2
- Work of breathing assessment
- Hydration status and feeding ability
- Risk factors identified
- Interventions and response
- Discharge instructions
Key Clinical Pearls
Diagnostic Pearls
- Bronchiolitis is clinical: No routine testing needed
- Peak illness at days 3-5: May worsen before better
- Wheezing ≠ asthma in infants: Especially first episode
- Apnea may be presenting sign: In young infants, especially preterm
- CXR often misleading: Atelectasis vs PNA difficult to distinguish
- Viral testing for cohorting: Not necessary for treatment decisions
Treatment Pearls
- Supportive care is evidence-based: The rest is not
- Bronchodilators don't work: No routine use
- Steroids don't help: Save them for asthma
- Antibiotics don't help: It's viral
- Nasal suctioning is key: Infants are obligate nasal breathers
- HFNC can prevent intubation: Evidence is growing
Disposition Pearls
- Admit if unsure: Bronchiolitis can worsen
- High-risk infants have low threshold: Better safe
- Educate, educate, educate: Parents need to know what to watch for
- Follow-up within 24-48h: Critical for early disease
References
- Ralston SL, et al. Clinical Practice Guideline: The Diagnosis, Management, and Prevention of Bronchiolitis. Pediatrics. 2014;134(5):e1474-e1502. (AAP Guideline)
- Florin TA, et al. Viral Bronchiolitis. Lancet. 2017;389(10065):211-224.
- Schuh S, et al. Effect of High-Flow Nasal Cannula in Bronchiolitis: A Randomized Clinical Trial. JAMA Pediatr. 2019;173(11):1021-1027.
- Franklin D, et al. A Randomized Trial of High-Flow Oxygen Therapy in Infants with Bronchiolitis. N Engl J Med. 2018;378(12):1121-1131.
- Hartling L, et al. Epinephrine for bronchiolitis. Cochrane Database Syst Rev. 2011;(6):CD003123.
- Fernandes RM, et al. Glucocorticoids for acute viral bronchiolitis in infants and young children. Cochrane Database Syst Rev. 2013;(6):CD004878.
- NICE Guideline NG9. Bronchiolitis in children: diagnosis and management. 2015 (updated 2021).
- UpToDate. Bronchiolitis in infants and children: Treatment, outcome, and prevention. 2024.