Overview/Definition
Definition:
• Bronchiolitis is an acute viral lower respiratory tract infection affecting small airways (bronchioles) in children <24 months, characterized by inflammation, edema, mucus production, and bronchiolar obstruction
Most common cause of hospitalization in infants requiring evidence-based respiratory support strategies including HFNC and CPAP.
Epidemiology:
• Affects 10-12% of infants during first year of life with hospitalization rate of 2-3% in infants <12 months
RSV accounts for 50-80% of cases globally
Peak incidence occurs in winter months with biennial outbreaks
Accounts for 16% of pediatric hospitalizations and significant healthcare burden worldwide.
Age Distribution:
• Peak incidence at 2-6 months of age with 90% of cases occurring in children <24 months
Premature infants and those with chronic lung disease at higher risk for severe disease requiring respiratory support
Adults and older children may develop similar illness but termed viral pneumonia rather than bronchiolitis.
Clinical Significance:
• High-yield topic for DNB Pediatrics and NEET SS examinations focusing on evidence-based respiratory support modalities, HFNC vs CPAP indications, and escalation protocols
Essential for understanding respiratory failure management, non-invasive ventilation principles, and resource allocation in pediatric intensive care.
Age-Specific Considerations
Newborn:
• Neonates <1 month with bronchiolitis have highest risk of apnea, respiratory failure, and need for intensive care
Lower threshold for respiratory support given immature respiratory mechanics and higher risk of fatigue
CPAP may be preferred over HFNC in neonates due to better evidence for preventing intubation.
Infant:
• Peak age group for bronchiolitis with majority of respiratory support requirements
Age 3-6 months represents highest risk period for severe disease and need for escalated care
HFNC vs CPAP decision depends on severity, institutional protocols, and clinical response
Risk factors include prematurity, chronic lung disease, congenital heart disease.
Child:
• Toddlers 12-24 months may still develop bronchiolitis but typically less severe than in younger infants
Diagnostic uncertainty increases with age as other viral pneumonias become more common
Respiratory support needs less common but when required, children may better tolerate interface-based interventions.
Adolescent:
• Bronchiolitis diagnosis inappropriate in adolescents as lower respiratory tract viral infections in this age group represent viral pneumonia or acute bronchitis
Different pathophysiology and treatment approaches required
HFNC or CPAP use in adolescents would be for different indications than bronchiolitis.
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Clinical Presentation
Symptoms:
• Prodromal upper respiratory symptoms (rhinorrhea, low-grade fever, cough) for 1-3 days followed by lower respiratory tract involvement
Progressive respiratory distress with tachypnea, increased work of breathing, feeding difficulties, irritability
Apnea episodes particularly in young infants <3 months or premature infants.
Physical Signs:
• Tachypnea, nasal flaring, intercostal and subcostal retractions, accessory muscle use
Auscultation reveals widespread fine crackles and/or wheeze, prolonged expiratory phase
Hypoxemia with oxygen saturations <90-92%
Signs of dehydration from poor feeding
Altered mental status in severe cases.
Severity Assessment:
• Mild: feeding normally, minimal respiratory distress, oxygen saturation >92% in air
Moderate: some feeding difficulties, moderate respiratory distress, oxygen requirement to maintain saturation >90%
Severe: poor feeding or unable to feed, significant respiratory distress, high oxygen requirements, signs of respiratory failure or apnea.
Differential Diagnosis:
• Viral pneumonia, bacterial pneumonia, asthma (first wheeze episode), pertussis, foreign body aspiration, congenital heart disease with pulmonary edema, gastroesophageal reflux with aspiration
In neonates, consider sepsis, metabolic disorders, or congenital anomalies
Clinical context and age crucial for differentiation.
Diagnostic Approach
History Taking:
• Detailed illness timeline with progression from upper to lower respiratory symptoms
Birth history including gestational age, chronic medical conditions, previous hospitalizations
Family history of asthma, allergies
Sick contacts and daycare attendance
Feeding pattern changes and urine output assessment for hydration status.
Investigations:
• Clinical diagnosis typically sufficient without routine testing
Chest X-ray if concern for pneumonia or complications (shows hyperinflation, peribronchial thickening, atelectasis)
Viral PCR testing if results would influence management or cohorting
Arterial blood gas if respiratory failure suspected
Basic metabolic panel if dehydrated.
Normal Values:
• Normal respiratory rate: <2 months <60/min, 2-12 months <50/min, 1-5 years <40/min
Normal oxygen saturation ≥92% in room air at sea level
Normal pH 7.35-7.45, pCOâ‚‚ 35-45 mmHg in blood gas
Normal chest X-ray in bronchiolitis shows hyperinflation without focal consolidation.
Interpretation:
• Respiratory distress assessment: tachypnea, retractions, nasal flaring, accessory muscle use, altered mental status
Hypoxemia defined as oxygen saturation <90-92%
Respiratory failure indicated by rising pCOâ‚‚ >50 mmHg, acidosis pH <7.25, or clinical exhaustion
These findings guide need for respiratory support escalation.
Management/Treatment
Acute Management:
• Supportive care cornerstone: oxygen therapy to maintain saturation >90-92%, adequate hydration (IV if unable to feed), nasal suctioning PRN
HFNC initiation: flow rates 1-8 L/min depending on weight, FiOâ‚‚ titrated to target saturation
CPAP initiation: pressures 5-8 cmHâ‚‚O with FiOâ‚‚ adjustment
Escalate if no improvement in 2-4 hours.
Chronic Management:
• No role for bronchodilators, corticosteroids, or antibiotics in typical bronchiolitis
Focus on supportive care and prevention of complications
Gradual weaning of respiratory support as clinical improvement occurs
Address feeding difficulties and ensure adequate nutrition during recovery
Monitor for post-viral wheeze or reactive airway disease.
Lifestyle Modifications:
• Hand hygiene and isolation precautions to prevent transmission
Avoid exposure to tobacco smoke which worsens respiratory symptoms
Maintain adequate hydration and nutrition during illness
Gradual return to normal activities as respiratory symptoms resolve
Environmental trigger avoidance during recovery period.
Follow Up:
• Hospitalized patients: daily assessment of respiratory status and support needs
Step-down criteria: stable on room air or minimal oxygen, adequate oral intake, stable vital signs
Outpatient follow-up: 24-48 hours after discharge to assess recovery
Long-term follow-up for high-risk patients or those with complications.
Age-Specific Dosing
Medications:
• HFNC flow rates: Weight-based dosing 1-2 L/kg/min (max 8-12 L/min in infants, higher in older children)
CPAP pressures: Start 5-6 cmHâ‚‚O, titrate to 6-8 cmHâ‚‚O based on response
FiOâ‚‚: Start 0.4-0.6, titrate to maintain SpOâ‚‚ >90-92%
No routine medications recommended (avoid bronchodilators, steroids, antibiotics).
Formulations:
• HFNC requires heated humidified high-flow system with appropriate nasal cannula sizing
CPAP requires appropriate interface selection (nasal mask, nasal pillows) and proper fitting to minimize leaks
Oxygen delivery systems must be calibrated and monitored continuously
No specific medications routinely indicated.
Safety Considerations:
• HFNC monitoring for nasal trauma, gastric distension, air leaks
CPAP monitoring for skin breakdown from interface pressure, gastric distension, pneumothorax risk
Both require continuous pulse oximetry and frequent clinical assessment
Avoid over-distension or excessive pressures that may impede venous return.
Monitoring:
• Continuous pulse oximetry with appropriate alarm limits
Vital signs every 2-4 hours including respiratory rate, heart rate, blood pressure
Work of breathing assessment using standardized scales
Feeding tolerance and hydration status monitoring
Blood gas analysis if clinical deterioration or failure to improve.
Prevention & Follow-up
Prevention Strategies:
• Hand hygiene most effective prevention strategy
RSV prophylaxis (palivizumab) for high-risk infants <24 months with chronic lung disease, congenital heart disease, or extreme prematurity
Avoid crowded places during RSV season
Breastfeeding protective against severe bronchiolitis
Tobacco smoke avoidance essential.
Vaccination Considerations:
• No specific vaccine available for RSV (leading cause of bronchiolitis) though vaccines in development
Standard childhood immunizations should continue as scheduled
Influenza vaccination for household contacts and caregivers recommended
COVID-19 vaccination for eligible household members to reduce overall viral transmission.
Follow Up Schedule:
• Post-hospitalization follow-up within 24-48 hours to assess recovery and identify complications
High-risk patients (premature, chronic conditions) may need more frequent monitoring
Routine pediatric care should resume after acute illness resolves
Pulmonology referral for recurrent wheeze or chronic respiratory symptoms.
Monitoring Parameters:
• Recovery indicators: normalization of respiratory rate and effort, improved feeding tolerance, stable oxygen saturations in room air
Growth monitoring important as bronchiolitis can impact nutrition
Development assessment in high-risk infants
Long-term respiratory health monitoring for post-viral complications.
Complications
Acute Complications:
• Respiratory failure requiring mechanical ventilation in 1-3% of hospitalized patients
Apnea episodes particularly in young infants (<6 months) or those born prematurely
Secondary bacterial infections (pneumonia, otitis media) in 10-15% of cases
Dehydration from poor feeding requiring IV fluid support.
Chronic Complications:
• Post-infectious wheeze in 30-40% of children following bronchiolitis, may persist for months
Increased risk of asthma development in later childhood
Prolonged respiratory symptoms in some children
Growth delays if severe or prolonged illness
Rare complications include bronchiolitis obliterans or chronic lung disease.
Warning Signs:
• Clinical deterioration: worsening respiratory distress despite support, rising oxygen requirements, altered mental status, poor feeding or decreased urine output
HFNC failure: no improvement after 2-4 hours, increasing work of breathing, rising COâ‚‚ levels
Signs requiring escalation to CPAP or intubation.
Emergency Referral:
• Immediate PICU referral for respiratory failure requiring mechanical ventilation, hemodynamic instability, altered mental status, or failure of non-invasive respiratory support
Any infant with apnea episodes requires inpatient monitoring
Escalation protocols should be clearly defined and followed consistently.
Parent Education Points
Counseling Points:
• Explain bronchiolitis as common viral infection of small airways that typically resolves with supportive care over 7-10 days
Discuss that antibiotics are not helpful as this is viral illness
Address expectations about respiratory support: HFNC and CPAP help breathing work while child recovers but do not shorten illness duration.
Home Care:
• Nasal suctioning with saline drops before feeds and sleep
Maintain adequate hydration with frequent small feeds
Elevate head of bed slightly for comfort
Monitor for signs of worsening: increased breathing difficulty, poor feeding, lethargy
Avoid smoke exposure and crowded places during recovery.
Medication Administration:
• No specific medications typically needed for bronchiolitis
Avoid over-the-counter cough and cold medications which can be harmful in young children
Acetaminophen may be used for fever if needed
Ensure any prescribed medications (rare) are given exactly as directed with proper measuring devices.
When To Seek Help:
• Seek immediate medical attention for: difficulty breathing or rapid breathing, blue lips or face, lethargy or decreased responsiveness, refusal to feed or signs of dehydration, fever in infants <3 months
Contact healthcare provider for: worsening symptoms after initial improvement, concerns about feeding or hydration.