Overview/Definition
Definition:
• Respiratory Distress Syndrome (RDS) is caused by surfactant deficiency in preterm infants leading to alveolar collapse and impaired gas exchange
- INSURE (Intubate-Surfactant-Extubate) involves brief intubation for surfactant delivery followed by immediate extubation to CPAP
- LISA (Less Invasive Surfactant Administration) delivers surfactant via thin catheter while infant breathes spontaneously on CPAP
- Both techniques aim to minimize ventilator-induced lung injury while ensuring effective surfactant delivery.
Epidemiology:
• RDS affects 60-80% of infants born at <28 weeks gestation, 15-30% at 32-36 weeks
- Incidence inversely related to gestational age and birth weight
- Male infants have 1.7x higher risk than females at same gestational age
- In India, RDS accounts for 24% of neonatal deaths, with regional variations in management approaches.
Age Distribution:
• Most common in preterm infants <34 weeks gestation due to immature lung development
- Peak incidence at 28-32 weeks when surfactant production is insufficient
- Late preterm infants (34-36 weeks) may develop RDS, especially with maternal diabetes or elective cesarean
- Term infants rarely affected unless maternal diabetes, asphyxia, or genetic surfactant disorders present.
Clinical Significance:
• Critical topic for DNB Pediatrics and NEET SS, frequently tested in clinical scenarios
- INSURE and LISA techniques represent paradigm shift toward less invasive respiratory support
- Early recognition and appropriate management significantly reduce mortality and long-term complications
- Understanding of these techniques essential for modern neonatal intensive care practice.
Age-Specific Considerations
Newborn:
• Extremely preterm (<28 weeks): High surfactant requirement, often need multiple doses and prolonged respiratory support
- Very preterm (28-31 weeks): Good candidates for INSURE/LISA, may avoid mechanical ventilation
- Moderate preterm (32-36 weeks): Lower surfactant needs, often respond well to single dose with CPAP
- Term infants: RDS rare, consider other causes like transient tachypnea, pneumonia, congenital anomalies.
Infant:
• First hours of life: RDS typically apparent within 4-6 hours of birth with progressive worsening
- 24-48 hours: Peak severity usually occurs, improvement expected with adequate treatment
- Recovery phase: Gradual improvement in oxygen requirements and compliance over 3-7 days
- Long-term effects: Risk of bronchopulmonary dysplasia if prolonged ventilation required.
Child:
• Most infants with RDS recover completely without long-term respiratory consequences
- Some may have subtle differences in lung function tests but usually asymptomatic
- Higher risk of respiratory infections in first 2 years of life
- School-age children generally have normal respiratory function if no chronic lung disease developed.
Adolescent:
• Long-term outcomes: Most have normal respiratory function by adolescence
- Exercise tolerance: Usually normal unless significant bronchopulmonary dysplasia occurred
- Pulmonary function: May show mild airway obstruction on detailed testing
- Sports participation: Generally unrestricted unless significant residual lung disease present.
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Clinical Presentation
Symptoms:
• Early signs: Tachypnea (>60 breaths/min), grunting, nasal flaring within first hours of life
- Progressive worsening: Increasing oxygen requirements, work of breathing over first 24-48 hours
- Severe cases: Central cyanosis, poor air entry, decreased activity, poor feeding
- Associated features: Hypothermia, hypotension, metabolic acidosis in severe cases.
Physical Signs:
• Inspection: Intercostal and subcostal retractions, use of accessory muscles, nasal flaring
- Auscultation: Diminished breath sounds, fine crepitations, asymmetric air entry if pneumothorax
- Chest wall: Compliant chest wall with prominent retractions, bell-shaped chest configuration
- General appearance: Pale, dusky, lethargic with poor perfusion in severe cases.
Severity Assessment:
• Mild RDS: FiO2 requirement <0.4, minimal retractions, stable vital signs
- Moderate RDS: FiO2 0.4-0.6, significant work of breathing, may need CPAP support
- Severe RDS: FiO2 >0.6, severe retractions, poor air entry, requires intubation and mechanical ventilation
- Silverman-Andersen score: Objective assessment tool using chest wall movement, retractions, nasal flaring.
Differential Diagnosis:
• Transient tachypnea of newborn: Usually resolves within 24-72 hours, less severe respiratory distress
- Pneumonia: May have maternal risk factors, elevated white count, positive blood culture
- Meconium aspiration: History of meconium-stained fluid, asymmetric findings, pneumothorax risk
- Congenital diaphragmatic hernia: Scaphoid abdomen, heart displacement, bowel sounds in chest.
Diagnostic Approach
History Taking:
• Gestational age assessment: Last menstrual period, ultrasound dating, physical examination findings
- Maternal factors: Diabetes, hypertension, medications, antenatal steroids received
- Delivery factors: Mode of delivery, fetal distress, resuscitation needed
- Risk factors: Male gender, multiple pregnancy, precipitous delivery, maternal illness.
Investigations:
• Chest X-ray: Ground-glass appearance, air bronchograms, low lung volumes characteristic of RDS
- Arterial blood gas: Hypoxemia, hypercarbia, metabolic acidosis indicate severity
- Lung ultrasound: Bilateral consolidated pattern with absent pleural sliding
- Blood tests: Complete blood count, blood glucose, electrolytes to rule out other causes.
Normal Values:
• Respiratory rate: Normal 30-60/min in term newborns, tachypnea >60/min abnormal
- Oxygen saturation: Target 88-94% for preterm infants to avoid hyperoxia complications
- Blood gas values: pH 7.25-7.45, PaCO2 35-45 mmHg, PaO2 50-70 mmHg on room air
- Chest X-ray: Normal lung volumes, clear lung fields, no air bronchograms.
Interpretation:
• Clinical scoring systems: Silverman-Andersen score >4 indicates moderate-severe RDS
- X-ray grading: Grade I (air bronchograms), II (reticulogranular pattern), III (whiteout)
- Lung ultrasound: More sensitive than X-ray for detecting RDS changes
- Response to treatment: Improvement in FiO2 requirements and work of breathing expected.
Management/Treatment
Acute Management:
• Immediate stabilization: Continuous positive airway pressure (CPAP) 5-6 cmH2O to prevent alveolar collapse
- INSURE technique: Intubate, deliver surfactant 100-200 mg/kg, extubate immediately to CPAP
- LISA technique: Insert thin catheter during spontaneous breathing, deliver surfactant, remove catheter
- Respiratory support: Avoid mechanical ventilation if possible, use CPAP or high-flow nasal cannula.
Chronic Management:
• Surfactant therapy: Poractant alfa (Curosurf) 100-200 mg/kg or beractant (Survanta) 100 mg/kg
- Ventilator settings: If intubation required, use gentle ventilation with low tidal volumes (4-6 mL/kg)
- Nutritional support: Early enteral feeding when stable, adequate protein and calories for growth
- Fluid management: Restrict fluids initially, monitor for patent ductus arteriosus.
Lifestyle Modifications:
• Prenatal interventions: Antenatal corticosteroids (betamethasone 12 mg x2 doses) reduce RDS severity
- Delivery timing: Avoid elective delivery before 39 weeks to reduce RDS risk
- Mode of delivery: Vaginal delivery preferred when possible, cesarean increases RDS risk
- Temperature management: Maintain normothermia to reduce oxygen consumption and metabolic demands.
Follow Up:
• NICU monitoring: Continuous pulse oximetry, frequent blood gases, chest X-rays as needed
- Weaning strategy: Gradual reduction in CPAP pressure and FiO2 as infant improves
- Complications monitoring: Watch for pneumothorax, patent ductus arteriosus, necrotizing enterocolitis
- Long-term follow-up: Pulmonary function, growth, neurodevelopment in high-risk infants.
Age-Specific Dosing
Medications:
• Surfactant dosing: Poractant alfa 100-200 mg/kg (1.25-2.5 mL/kg), may repeat if needed
- Beractant (Survanta): 100 mg/kg (4 mL/kg) intratracheally, up to 4 doses in 48 hours
- Calfactant (Infasurf): 105 mg/kg (3 mL/kg) intratracheally every 12 hours if needed
- Sedation for INSURE: Morphine 0.05-0.1 mg/kg IV or fentanyl 1-2 mcg/kg IV.
Formulations:
• Poractant alfa: Intratracheal suspension 80 mg/mL in single-use vials
- Beractant: Intratracheal suspension 25 mg/mL, warm to room temperature before use
- Administration: Divide dose into 2-4 aliquots, instill in different positions
- Storage: Refrigerate unopened vials, warm to room temperature before use.
Safety Considerations:
• Surfactant administration: Monitor for acute changes in oxygenation, blood pressure during instillation
- INSURE procedure: Have resuscitation equipment ready, experienced personnel present
- LISA technique: Requires specific training, may cause bradycardia or desaturation
- Repeat dosing: Generally not needed with LISA, may repeat INSURE if significant deterioration.
Monitoring:
• Immediate post-surfactant: Continuous monitoring of heart rate, oxygen saturation, blood pressure
- FiO2 requirements: Should decrease within 30-60 minutes of effective surfactant administration
- Chest X-ray: Improvement in lung expansion and aeration within 6-12 hours
- Complications: Watch for pneumothorax, surfactant reflux, hemodynamic instability.
Prevention & Follow-up
Prevention Strategies:
• Antenatal steroids: Betamethasone 12 mg IM x2 doses 24 hours apart for mothers 24-34 weeks
- Optimal timing: Maximum benefit 24 hours to 7 days after completion of steroid course
- Delivery planning: Transfer to tertiary care center with NICU facilities for high-risk pregnancies
- Avoid elective deliveries: Before 39 weeks gestation to reduce RDS risk.
Vaccination Considerations:
• Standard immunizations: Follow routine schedule based on chronological age, not corrected age
- RSV prophylaxis: Palivizumab monthly during RSV season for high-risk preterm infants
- Influenza vaccine: Annual vaccination for household contacts of high-risk infants
- Pneumococcal vaccine: Especially important for infants with chronic lung disease.
Follow Up Schedule:
• NICU follow-up: Weekly visits first month, then monthly until 6 months corrected age
- Pulmonary assessment: Chest X-ray, oxygen requirement monitoring during hospitalization
- Growth monitoring: Weight, length, head circumference plotted on appropriate growth charts
- Developmental follow-up: Formal assessment at 6, 12, 18, 24 months corrected age.
Monitoring Parameters:
• Respiratory status: Oxygen requirement, work of breathing, chest X-ray findings
- Growth parameters: Plot on preterm growth charts, watch for failure to thrive
- Feeding tolerance: Volume advancement, gastric residuals, necrotizing enterocolitis signs
- Neurological assessment: Tone, reflexes, social interaction appropriate for gestational age.
Complications
Acute Complications:
• Pneumothorax: Sudden deterioration, asymmetric breath sounds, requires immediate decompression
- Air leak syndromes: Pneumomediastinum, pneumopericardium, pulmonary interstitial emphysema
- Patent ductus arteriosus: Left-to-right shunt worsening respiratory status, may need closure
- Pulmonary hemorrhage: Bleeding into lungs, often associated with surfactant therapy.
Chronic Complications:
• Bronchopulmonary dysplasia: Chronic lung disease requiring oxygen at 36 weeks corrected age
- Retinopathy of prematurity: Abnormal retinal vascular development from oxygen exposure
- Neurodevelopmental delays: Higher risk in infants requiring prolonged ventilation
- Growth restriction: Poor weight gain, failure to thrive in severely affected infants.
Warning Signs:
• Sudden deterioration: Rapid increase in oxygen requirements, decreased air entry, bradycardia
- Pneumothorax signs: Asymmetric chest movement, shift in cardiac impulse, decreased saturation
- Infection: Temperature instability, increased apnea, feeding intolerance, lethargy
- Equipment malfunction: Check ventilator settings, endotracheal tube position, circuit integrity.
Emergency Referral:
• Transport indications: FiO2 >0.6, need for mechanical ventilation, cardiovascular instability
- Specialist consultation: Pediatric pulmonologist for chronic lung disease, cardiac surgery for PDA
- Emergency procedures: Chest tube insertion for tension pneumothorax, ECMO for refractory hypoxemia
- Ethical consultation: For extremely preterm infants with poor prognosis.
Parent Education Points
Counseling Points:
• RDS explanation: Immature lungs lacking surfactant, common in preterm babies, usually improves
- INSURE/LISA benefits: Less invasive techniques reduce need for long-term ventilation
- Expected course: Initial worsening first 1-2 days, then gradual improvement over week
- Long-term outlook: Most infants recover completely without long-term respiratory problems.
Home Care:
• Positioning: Semi-upright position may ease breathing, avoid prone position until stable
- Environmental factors: Minimize exposure to smoke, strong odors, respiratory irritants
- Feeding support: May need frequent small feeds, monitor for signs of respiratory distress during feeding
- Signs of improvement: Decreased work of breathing, better color, more active and alert.
Medication Administration:
• Bronchodilators: If prescribed for chronic lung disease, use spacer device properly
- Diuretics: Give as prescribed, monitor for electrolyte imbalances, dehydration
- Caffeine: May be prescribed for apnea of prematurity, give at same time daily
- Oxygen therapy: If going home on oxygen, ensure proper equipment maintenance and safety.
When To Seek Help:
• Breathing difficulties: Increased work of breathing, retractions, grunting, color changes
- Feeding problems: Poor feeding, vomiting, excessive sleepiness during feeds
- Temperature changes: Fever, hypothermia, lethargy, irritability
- Equipment issues: Oxygen equipment malfunction, CPAP problems, unusual alarms.