FCPS Paediatrics TOACS · Interactive Station

✅ Candidate's answer:
• Primary defect: Deficiency of pulmonary surfactant (produced by type II alveolar cells). Surfactant production begins at ~24-28 weeks, matures by 35-36 weeks.
• Pathophysiology:
- Surfactant deficiency → increased alveolar surface tension → alveolar collapse at end-expiration (atelectasis).
- Atelectasis → decreased lung compliance → increased work of breathing (tachypnea, grunting, retractions).
- V/Q mismatch → hypoxemia and hypercapnia.
- Hypoxia and acidosis → pulmonary vasoconstriction → persistent pulmonary hypertension (PPHN).
- Capillary leakage → proteinaceous exudate forms hyaline membranes (eosinophilic membranes lining alveoli).
- A vicious cycle of atelectasis, injury, and inflammation.
• Risk factors for RDS: Prematurity, maternal diabetes, C-section without labor, male sex, second twin, asphyxia, cold stress, maternal hypertension (protective? – reduced risk).

✅ Candidate's answer:
• Indication: Pregnant women at risk of preterm delivery between 24-34 weeks (up to 36 weeks in some guidelines).
• Agents: Betamethasone (12 mg IM x2 doses, 24 hours apart) or Dexamethasone (6 mg IM x4 doses, 12 hours apart). Betamethasone is more commonly used.
• Mechanism: Accelerates fetal lung maturation → increases surfactant production and release, improves lung compliance, reduces RDS severity and mortality.
• Optimal timing: Maximal benefit if the first dose is given >24 hours to ≤7 days before delivery. Partial course (one dose) still provides some benefit.
• Effectiveness: Reduces RDS (by ~30-40%), IVH, NEC, and neonatal mortality. Does NOT prevent TTN.
• This infant received only one dose – partial benefit.
• Rescue course: A single repeat course may be given if >14 days have elapsed and delivery is still imminent (not more than 2 courses total).

✅ Candidate's answer:
• Indications for surfactant:
- Preterm infant with RDS requiring intubation and mechanical ventilation (or CPAP with FiO2 >0.4).
- Prophylactic surfactant (no longer routine) – selective/early rescue is preferred.
- Early rescue surfactant (within 2-6 hours of life if FiO2 >0.3-0.4) is associated with reduced BPD and mortality.
• INSURE technique (INtubate – SURfactant – Extubate):
- Intubate, give surfactant, then extubate to CPAP (within minutes).
- Avoids prolonged intubation, reduces BPD.
• MIST / LISA (Minimally Invasive Surfactant Therapy / Less Invasive Surfactant Administration):
- Administer surfactant via a thin catheter (5F feeding tube) passed into the trachea during spontaneous breathing on CPAP.
- No intubation, no positive pressure ventilation before surfactant.
- Associated with lower rates of BPD, death, and need for mechanical ventilation compared to INSURE.
• Surfactant preparations: Natural (beractant, calfactant, poractant alfa) vs synthetic (less effective). Natural is preferred.
• Dose: Beractant (Survanta) 100-200 mg/kg (4-5 mL/kg); repeat doses (up to 3-4) may be given if RDS persists.

✅ Candidate's answer:
• Pressure-limited ventilation (PLV): Delivers a set inspiratory pressure; tidal volume varies with changes in lung compliance. High risk of volutrauma (overdistension) when compliance improves, and atelectrauma (low tidal volumes) when compliance worsens.
• Volume-targeted ventilation (VTV) / Volume-guaranteed (VG): Delivers a set tidal volume (usually 4-6 mL/kg). The ventilator automatically adjusts inspiratory pressure to achieve the target volume. Reduces variability in tidal volume.
• Evidence (multiple randomized controlled trials and meta-analyses):
- VTV (compared to PLV) significantly reduces:
  • Bronchopulmonary dysplasia (BPD) (relative risk ~0.7-0.8).
  • Pneumothorax (reduced incidence).
  • Duration of mechanical ventilation.
  • Mortality (trend towards reduction).
- VTV also reduces severe IVH and periventricular leukomalacia (PVL) in some studies.
• Preferred strategy: Volume-targeted ventilation is the recommended mode for preterm infants with RDS requiring intubation.
• This infant should be managed on VTV (e.g., SIMV + VG, PC-VG, PRVC).

✅ Candidate's answer:
• Current recommendation (SUPPORT, COIN, VON trials): For infants ≥25-28 weeks with RDS, early CPAP with selective surfactant (intubate only if CPAP fails) is preferred over routine intubation.
• Benefits of early CPAP:
- Reduces need for intubation and mechanical ventilation.
- Reduces BPD (chronic lung disease).
- No increase in mortality or air leak.
- Preserves spontaneous breathing.
• CPAP settings: Start at 6-8 cm H2O, FiO2 titrated to SpO2 90-95%.
• Indications for intubation and surfactant after CPAP trial:
- FiO2 >0.3-0.4 to maintain SpO2 >90%.
- Severe retractions, grunting, or apnea.
- Respiratory acidosis (pH <7.2, PaCO2 >60-65).
- This infant was already intubated at delivery due to severe RDS (placental abruption, partial steroids). So CPAP alone was not an option.
• After surfactant, attempt extubation to CPAP (INSURE) as soon as possible.

✅ Candidate's answer:
• Indications for HFOV/HFJV:
1️⃣ Severe RDS refractory to conventional ventilation (OI >25-30).
2️⃣ Air leak syndromes (pneumothorax, pulmonary interstitial emphysema – PIE).
3️⃣ To avoid high tidal volumes in extreme prematurity (<25 weeks).
• Mechanism: Delivers very small tidal volumes (1-2 mL/kg) at high rates (300-900/min). Maintains lung volume (distending pressure) to prevent atelectasis and reduce volutrauma.
• Evidence on BPD:
- Meta-analyses show that HFOV does not significantly reduce BPD when used as primary mode compared to conventional ventilation.
- However, HFOV may reduce pneumothorax and severe IVH.
- HFOV is a rescue therapy, not first-line.
- Current practice: Use HFOV when conventional ventilation fails (high FiO2, high MAP, persistent acidosis).
• Monitoring: Lung volume (chest X-ray) to avoid overdistension.

✅ Candidate's answer:
• Permissive hypercapnia (PHC): Accepting higher PaCO2 levels (e.g., 55-65 mmHg or even higher) to reduce ventilator pressures and tidal volumes, thereby minimizing volutrauma and lung injury.
• Rationale: Avoiding hypocarbia (PaCO2 <35 mmHg) is critical because hypocarbia causes cerebral vasoconstriction and is associated with periventricular leukomalacia (PVL) and cerebral palsy.
• Current recommendations:
- Avoid hypocarbia (PaCO2 <35 mmHg).
- Moderate permissive hypercapnia (PaCO2 45-55 mmHg) is safe and likely reduces BPD and PVL.
- Extreme hypercapnia (PaCO2 >65-70 mmHg with pH <7.2) is not safe (risk of IVH, pulmonary hypertension).
- Maintain pH >7.25 (if pH is low despite PaCO2, consider bicarbonate or adjusting ventilation).
• Practice: Target PaCO2 45-55 mmHg for preterm infants on mechanical ventilation.

✅ Candidate's answer:
• Classic RDS findings (before surfactant):
- Low lung volumes (atelectasis).
- Diffuse reticulogranular (“ground-glass”) pattern – due to collapsed alveoli alternating with dilated terminal bronchioles.
- Air bronchograms (air-filled bronchi standing out against opaque lung parenchyma).
- Symmetrical bilateral involvement.
• After surfactant administration:
- Rapid improvement within hours: lung volumes increase, reticulogranular pattern clears, air bronchograms resolve.
- Asymmetric expansion may occur (usually right lung expands more quickly).
- May see asymmetric aeration (left lung slower to clear).
- If no improvement, consider second dose of surfactant.
• Differential diagnosis (similar X-ray): Group B streptococcal pneumonia (indistinguishable clinically and radiologically – treat both with antibiotics until cultures negative).

✅ Candidate's answer:
• Complications of RDS itself:
- Hypoxemia, acidosis, PPHN.
- Intraventricular hemorrhage (IVH) – due to fluctuating cerebral blood flow.
- Pulmonary hemorrhage.
- Multi-organ dysfunction.
• Complications of mechanical ventilation (ventilator-induced lung injury – VILI):
- Air leak syndromes: Pneumothorax (most common), pneumomediastinum, pulmonary interstitial emphysema (PIE), pneumopericardium, subcutaneous emphysema.
- Bronchopulmonary dysplasia (BPD) – chronic lung disease.
- Subglottic stenosis (from prolonged intubation).
- Ventilator-associated pneumonia.
• Complications of surfactant therapy:
- Transient desaturation, bradycardia, hypotension during administration.
- Pulmonary hemorrhage (rare, but increased risk with natural surfactants).
- Airway obstruction (if dose is too large or given too fast).
• Prevention of air leaks: Use volume-targeted ventilation, avoid high PIP/PEEP, avoid high tidal volumes, early extubation to CPAP.

✅ Candidate's structured answer:
• “Your baby was born early, at 30 weeks. His lungs are not fully developed because they haven't had time to produce enough surfactant – a natural soap-like substance that keeps the air sacs open.”
• “Without surfactant, his lungs collapse after each breath, making it very hard to breathe. So we gave him surfactant medicine through the breathing tube, and we are using a ventilator to do the work of breathing for him.”
• “The breathing machine will support him until his own lungs mature enough. Most babies with RDS need the ventilator for a few days to a week. As he improves, we will gradually reduce the support and let him breathe more on his own.”
• “We are using a safe mode of ventilation called volume-targeted ventilation, which gives him exactly the right amount of air with each breath and reduces the risk of lung injury.”
• “We will also try to take the breathing tube out as soon as possible and put him on CPAP (gentle pressure through small prongs in the nose) – this is better for his lungs.”
• “We will keep you updated daily. You can visit, touch, and talk to him – this helps him heal. You are a very important part of his care team.”

✅ Candidate's answer:
• RDS (preterm or term diabetic mother): Onset at birth or within hours, grunting, retractions, cyanosis, ground-glass CXR, low lung volumes, air bronchograms. Surfactant deficiency.
• TTN (term, C-section, no labor): Onset within 2-6 hours, mild tachypnea, pink, CXR shows fluid in fissure, perihilar streaking, normal/high lung volumes, resolves in 24-72 hours.
• MAS (post-term, meconium-stained fluid): Onset at birth, severe respiratory distress, CXR shows coarse infiltrates, hyperinflation, pneumothorax, patchy atelectasis. May have PPHN.
• Key distinguishing feature: Chest X-ray (ground-glass = RDS; fluid in fissure = TTN; coarse patchy infiltrates = MAS). Clinical history also crucial.

✅ Candidate's answer:
• Caffeine citrate (methylxanthine): Standard of care for apnea of prematurity, but also benefits infants with RDS.
• Benefits of early caffeine (within first 3 days of life):
- Reduces the risk of BPD (by ~30-40%).
- Facilitates extubation (reduces need for mechanical ventilation).
- Reduces the need for postnatal corticosteroids.
- Improves neurodevelopmental outcomes (CP, cognitive delay) at 18-21 months.
• Dose: Loading 20 mg/kg IV/PO (caffeine citrate), maintenance 5-10 mg/kg/day once daily.
• Mechanism: Respiratory stimulant (increases central respiratory drive), improves diaphragmatic contractility, anti-inflammatory effects in the lung.
• Recommendation: Start caffeine as early as possible (within 24-48 hours) in infants with RDS who are at risk of apnea or require mechanical ventilation.

✅ Candidate's answer:
• Short-term prognosis: With modern treatment (antenatal steroids, surfactant, volume-targeted ventilation, caffeine), survival is >95% for a 30-week infant.
• Long-term pulmonary outcomes:
- Mild to moderate BPD occurs in ~20-40% of 30-week infants (less than in more premature infants).
- Most infants wean off oxygen by 36 weeks PMA or within a few months after discharge.
- Increased risk of reactive airways disease (wheezing) and respiratory infections (RSV) in the first 2 years.
• Neurodevelopmental outcomes:
- 30-week infants generally have good outcomes, but the risk of mild cognitive delay, ADHD, learning disabilities is slightly higher than term infants.
- Severe IVH or PVL (which can occur with severe RDS) is a major risk factor for cerebral palsy.
• This infant has no documented IVH yet – surveillance cranial ultrasound is needed.
• Follow-up: Neonatal follow-up program for growth, development, and hearing/vision screening.

✅ Candidate's answer:
• Proven preventive strategies:
1️⃣ Antenatal corticosteroids (betamethasone 12 mg IM x2, 24h apart) – most effective.
2️⃣ Delayed cord clamping (≥60 seconds) – improves circulatory stability, reduces need for transfusions, and may modestly reduce RDS/BPD.
3️⃣ Elective C-section avoidance before 39 weeks (without medical indication).
4️⃣ Prevention of preterm birth (progesterone, cervical cerclage, tocolytics).
5️⃣ Antenatal magnesium sulfate – given for neuroprotection (reduces CP), not for RDS prevention.
• Experimental/preclinical: Maternal vitamin D, myoinositol, but not established.
• Postnatal prevention of BPD (after RDS): Volume-targeted ventilation, early caffeine, early CPAP, vitamin A (modest effect), surfactant, nutrition.