Overview/Definition
Definition:
Respiratory Syncytial Virus (RSV) bronchiolitis is acute inflammatory injury of bronchioles caused by RSV, leading to airway obstruction and respiratory distress
Palivizumab is monoclonal antibody for RSV prophylaxis in high-risk infants.
Epidemiology:
RSV infects nearly all children by age 2 years in India
Hospitalization rate 1-3% in healthy infants, up to 10% in high-risk groups
Peak season October-February in North India, year-round in tropical regions.
Age Distribution:
Most severe disease in infants <6 months
Peak hospitalization age 2-6 months
Premature infants and those with chronic conditions at highest risk for severe disease requiring intensive care.
Clinical Significance:
Leading cause of hospitalization in infants worldwide
Mortality rate 1-3% in hospitalized cases, higher in high-risk groups
Long-term sequelae include recurrent wheezing and asthma development.
Age-Specific Considerations
Newborn:
Highest risk for severe RSV disease due to immature immune system and small airways
Maternal antibodies provide some protection but wane by 2-3 months
Palivizumab indicated for qualifying high-risk newborns.
Infant:
Peak severity 2-6 months when maternal antibodies decline
Clinical presentation ranges from mild URTI to severe bronchiolitis requiring mechanical ventilation
Feeding difficulties and apnea episodes common.
Child:
Generally milder disease after age 2 years due to larger airways and developed immunity
May present as cold symptoms or mild bronchitis
Previous RSV infection provides partial protection against severe reinfection.
Adolescent:
RSV infection uncommon and usually mild, resembling common cold
Severe disease rare except in immunocompromised patients
May serve as reservoir for transmission to high-risk infants in household.
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Clinical Presentation
Symptoms:
Gradual onset over 2-5 days: rhinorrhea, low-grade fever, decreased feeding, irritability
Progressive respiratory distress: cough, tachypnea, increased work of breathing, apnea (especially in young infants).
Physical Signs:
Tachypnea, subcostal/intercostal retractions, nasal flaring, grunting, wheeze, fine crackles on auscultation
Prolonged expiratory phase, hyperinflation of chest
Hypoxemia in severe cases.
Severity Assessment:
Mild: Minimal respiratory distress, feeding >50% normal, oxygen saturation >95%
Moderate: Moderate distress, feeding 50-75% normal, oxygen requirement
Severe: Significant distress, poor feeding, high oxygen requirement.
Differential Diagnosis:
Bacterial pneumonia, asthma exacerbation, viral pneumonia (other causes), pertussis, foreign body aspiration, congenital heart disease with heart failure, gastroesophageal reflux with aspiration.
Diagnostic Approach
History Taking:
Age, prematurity, underlying conditions (heart disease, lung disease, immunodeficiency), household contacts with respiratory illness, daycare attendance, RSV season, feeding patterns, urine output.
Investigations:
RSV rapid antigen test or PCR from nasopharyngeal specimen
Chest X-ray shows hyperinflation, bilateral infiltrates
Blood gas analysis if severe
Complete blood count usually shows lymphocytosis.
Normal Values:
Oxygen saturation >95% in room air, respiratory rate <60/min in infants, <40/min in children >1 year
Normal feeding pattern, adequate urine output indicating good hydration.
Interpretation:
Positive RSV test confirms diagnosis but not required for clinical management
Chest X-ray helps rule out complications (pneumothorax, bacterial superinfection)
Blood gas shows hypoxemia and possibly hypercarbia in severe cases.
Management/Treatment
Acute Management:
Supportive care: Oxygen therapy to maintain saturation >90%, nasal suctioning, adequate hydration (IV if poor oral intake)
High-flow nasal cannula or CPAP for moderate-severe cases
Avoid bronchodilators, corticosteroids.
Chronic Management:
Most children recover completely within 7-10 days
Monitor for post-infectious wheezing episodes
Some children develop recurrent wheezing requiring inhaled bronchodilators
Long-term pulmonary function monitoring in severe cases.
Lifestyle Modifications:
Strict hand hygiene, avoid exposure to tobacco smoke, limit exposure to crowded places during RSV season
Breastfeeding provides protective antibodies
Proper nutrition to support immune function.
Follow Up:
Daily assessment during hospitalization
Outpatient follow-up within 24-48 hours post-discharge
Monitor for feeding recovery, respiratory symptoms resolution, development of post-infectious complications.
Age-Specific Dosing
Medications:
Palivizumab: 15 mg/kg IM monthly during RSV season (typically 5 doses)
No specific antiviral therapy recommended for RSV bronchiolitis
Oxygen therapy as needed to maintain saturation >90%.
Formulations:
Palivizumab: 50 mg and 100 mg vials for intramuscular injection
Reconstitute with sterile water, use within 6 hours
Give in anterolateral thigh muscle
Supportive medications as needed for symptoms.
Safety Considerations:
Palivizumab contraindicated in known hypersensitivity
Monitor injection site reactions
Avoid ribavirin except in severe immunocompromised cases
No role for antibiotics unless bacterial superinfection confirmed.
Monitoring:
Continuous pulse oximetry for hospitalized patients
Monitor respiratory rate, work of breathing, feeding tolerance
Daily weights to assess hydration status
Watch for apnea episodes in young infants.
Prevention & Follow-up
Prevention Strategies:
Hand hygiene most important prevention measure
Avoid exposure to ill contacts during RSV season
Palivizumab prophylaxis for qualified high-risk infants
Promote breastfeeding and avoid tobacco smoke exposure.
Vaccination Considerations:
No RSV vaccine currently available
Routine immunizations should be maintained
RSV prophylaxis with palivizumab does not interfere with response to other vaccines
Maternal immunization under research.
Follow Up Schedule:
High-risk infants: Monthly during RSV season for palivizumab administration
Post-infection: Weekly during acute phase, then monthly for 3 months to monitor for complications
Annual pulmonary function if severe disease.
Monitoring Parameters:
Growth and development, feeding patterns, respiratory symptoms, frequency of wheezing episodes
For palivizumab recipients: Monitor for breakthrough RSV infection, injection site reactions, continued eligibility.
Complications
Acute Complications:
Respiratory failure requiring mechanical ventilation, apnea episodes, secondary bacterial pneumonia, pneumothorax from positive pressure ventilation, dehydration from poor feeding, electrolyte imbalances.
Chronic Complications:
Post-infectious wheezing (30-40% of patients), increased risk of asthma development, reduced lung function in long term, increased susceptibility to subsequent respiratory infections.
Warning Signs:
Worsening respiratory distress, apnea episodes, poor feeding with dehydration, lethargy, high fever suggesting bacterial superinfection, cyanosis, altered mental status.
Emergency Referral:
Respiratory distress requiring oxygen, apnea episodes, poor feeding with signs of dehydration, age <3 months with any respiratory symptoms, high-risk infant with RSV infection.
Parent Education Points
Counseling Points:
RSV bronchiolitis is common and usually mild but can be serious in young infants
No specific treatment available - supportive care is mainstay
Most children recover completely
Prevention through hygiene most important.
Home Care:
Maintain adequate hydration, use saline nasal drops and gentle suctioning, elevate head of bed slightly
Monitor breathing pattern, feeding, urine output
Avoid smoke exposure
Continue breastfeeding.
Medication Administration:
Palivizumab given monthly by healthcare provider - maintain appointment schedule
No home medications typically needed for bronchiolitis
Avoid over-the-counter cold medications in infants.
When To Seek Help:
Immediate medical attention for difficulty breathing, poor feeding, decreased wet diapers, lethargy, fever in infant <3 months
Any concerns about breathing pattern or feeding in high-risk infant.