Chapter 20 · Chronic Lung Disease of Prematurity (BPD)

Incidence · Pathophysiology · Clinical features · Extrapulmonary complications · Management · Prognosis · The future
📌 Core principles: BPD is the most common chronic lung disease of infancy, defined by oxygen requirement at 36 weeks PMA. Pathophysiology: arrested alveolarization (simplified alveoli), dysmorphic capillaries, inflammation, oxidative stress. Clinical: tachypnoea, retractions, wheeze, hypoxaemia, hypercapnia, pulmonary hypertension. Extrapulmonary: growth failure, neurodevelopmental delay, gastroesophageal reflux, anaemia of prematurity, osteopenia. Management: respiratory support (CPAP, HFNC, low-flow O2), diuretics, bronchodilators, inhaled steroids (controversial), nutrition (high-calorie, vitamin supplements), RSV prophylaxis (palivizumab). Prognosis: many improve by 2-3 years, but risk of asthma, exercise intolerance, pulmonary hypertension. Future: stem cells, anti-inflammatory strategies (azithromycin, vitamin A), less invasive ventilation, postnatal steroids targeted.

📖 Chronic Lung Disease of Prematurity (BPD) – Key Concepts

📊 Incidence & Definitions
Increases with decreasing gestational age: 10-15% at 28 weeks, >50% at <26 weeks. NIH definition: oxygen requirement at 36 weeks PMA; severity graded mild, moderate, severe.
🧬 Pathophysiology
Arrested alveolar development (simplified alveoli), dysmorphic capillaries, inflammation (cytokines, neutrophils), oxidative stress, mechanical ventilation injury (volutrauma, oxygen toxicity). Chorioamnionitis and genetic susceptibility.
🩺 Clinical features (respiratory)
Tachypnoea, subcostal/intercostal retractions, wheeze, crackles, hypoxaemia (oxygen dependency), hypercapnia, pulmonary hypertension (PHT). Exacerbations triggered by viral infections (RSV).
❤️ Extrapulmonary complications
Growth failure (poor weight gain), neurodevelopmental delay (higher risk cerebral palsy, cognitive deficits), GERD (gastroesophageal reflux), anaemia of prematurity, osteopenia/metabolic bone disease, systemic hypertension.
💊 Management (multidisciplinary)
Respiratory: CPAP, nasal high-flow, low-flow oxygen (target SpO2 90-95%), diuretics (spironolactone, thiazides, furosemide), bronchodilators (salbutamol), inhaled corticosteroids (budesonide – limited evidence). Nutrition: high-calorie formula/ breastmilk fortifier, vitamin D, iron, calcium. RSV prophylaxis (palivizumab monthly during season). Treat pulmonary hypertension (sildenafil, bosentan). Avoid routine systemic steroids.
📈 Prognosis & Future
Mortality has decreased (improved perinatal care). Long-term: asthma-like symptoms, reduced exercise capacity, recurrent wheeze, increased risk of COPD in adulthood. Pulmonary hypertension may persist. Future strategies: stem cell therapy (mesenchymal stromal cells), antioxidants (vitamin A, N-acetylcysteine), cytokine modulation (azithromycin), less invasive ventilation (HFOV, volume-targeted), targeted postnatal steroids.

🔎 Symptom-based approach: Tachypnoea, oxygen dependency, wheeze in preterm infant

1️⃣
Preterm infant (26 weeks) at 36 weeks PMA still requires 0.3 L/min oxygen to maintain SpO2 >90%. Diagnosis?
Bronchopulmonary dysplasia (BPD), moderate. Manage with low-flow oxygen, diuretics if fluid overload, treat GERD.
2️⃣
Infant with BPD and recurrent wheeze, oxygen desaturation during feeds, poor weight gain.
Likely reactive airway disease and GERD. Trial of bronchodilators, thickened feeds, prokinetics, consider inhaled steroids.
3️⃣
Ex-premature infant with chronic respiratory symptoms, echocardiogram shows suprasystemic pulmonary artery pressure, right ventricular hypertrophy.
Pulmonary hypertension (PHT) secondary to BPD. Start sildenafil, bosentan, optimise oxygen, consider prostacyclin.
4️⃣
Infant with BPD and progressive hypoxaemia, not responding to high-flow nasal cannula. Next respiratory support?
NIPPV/BiPAP or intubation. Evaluate for airway malacia, pulmonary hypertension, infection.
📊 BPD severity (NIH criteria at 36 weeks PMA or discharge): Mild: room air; Moderate: need <30% oxygen; Severe: need ≥30% oxygen or positive pressure/ventilation.

📋 BPD management (respiratory, nutrition, complications)

🫁
Respiratory support in established BPD
▪️ Low-flow oxygen via nasal cannula (target SpO2 90-95%). Wean as tolerated.
▪️ CPAP or NIPPV for moderate-severe BPD with hypercapnia.
▪️ Inhaled bronchodilator (salbutamol) for reactive airway symptoms.
▪️ Diuretics (spironolactone ± furosemide) for fluid overload, but long-term use controversial.
▪️ Inhaled corticosteroids (budesonide) – not routinely, may reduce exacerbations in some.
▪️ Pulmonary hypertension: sildenafil, bosentan, refer to specialist.
🍼
Nutrition and growth
▪️ High-calorie formula/breastmilk fortifier (target 150-160 kcal/kg/day).
▪️ Monitor FTT; consider nasogastric tube or gastrostomy if poor oral intake.
▪️ Supplement vitamins A, D, E, K, iron, calcium, phosphate.
▪️ Treat GERD (positioning, thickened feeds, PPI – omeprazole).
🦠
Infection prevention & complications
▪️ RSV prophylaxis: palivizumab monthly during RSV season (eligible infants).
▪️ Annual influenza vaccine for caregivers and eligible infants.
▪️ Treat intercurrent LRTI promptly (viral PCR, antibiotics if bacterial).
▪️ Monitor for pulmonary hypertension with serial echocardiograms.
📈
Long-term follow-up
▪️ Neurodevelopmental surveillance (cerebral palsy, hearing, vision).
▪️ Pulmonary follow-up: monitor for asthma, exercise intolerance, school performance.
▪️ Avoid tobacco smoke exposure, ensure vaccinations up to date.

💡 Reflex prompts – Chronic Lung Disease of Prematurity

📊 A 28-week preterm infant at 36 weeks PMA requires 25% oxygen. BPD severity?
Moderate BPD (oxygen <30% at 36 weeks).
🧬 Most common pathological finding in new BPD.
Arrested alveolar development (simplified alveoli, dysmorphic capillaries).
🩺 First-line diuretic for chronic lung disease in BPD (avoid potassium loss).
Spironolactone (potassium-sparing). Furosemide may be added for acute fluid overload.
🦠 A premature infant with BPD during RSV season. Prophylaxis?
Palivizumab (monoclonal antibody) monthly intramuscular.
💊 An infant with BPD and documented pulmonary hypertension (PHT). Oral therapy?
Sildenafil (PDE5 inhibitor) or bosentan (endothelin receptor antagonist).
❤️ Most common extrapulmonary complication in BPD (beyond respiratory).
Growth failure and neurodevelopmental delay.
🔬 A 32-week preterm infant with oxygen dependency, hypercapnia, and right ventricular hypertrophy on echo. Next step?
Echocardiogram to assess pulmonary pressure; treat PH with sildenafil, optimise oxygenation.
📉 Inhaled corticosteroid (budesonide) in BPD – role?
May reduce exacerbations in some patients, but not routine. Systemic steroids avoided due to neurodevelopmental harm.
🧪 Most effective preventive measure for BPD (antenatal).
Antenatal corticosteroids (betamethasone) reduces incidence and severity.
📊 A 24-week infant with severe BPD, chronic hypoxaemia, feeding difficulties. Important long-term prognosis?
High risk of pulmonary hypertension, recurrent respiratory infections, and neurodevelopmental impairment. Multidisciplinary follow-up essential.