What is the prognosis for premature infants born at 24-27 weeks of gestation with chronic lung disease (CLD) but without pulmonary hypertension (PH)?

Prognosis for Premature Infants (24-27 Weeks) with CLD but WITHOUT Pulmonary Hypertension

Premature infants born at 24-27 weeks with chronic lung disease but without pulmonary hypertension have substantially better outcomes than those with pulmonary hypertension, with the majority demonstrating normal neurodevelopment (69%) by ages 2-5 years and gradual improvement in respiratory function over time. 1

Survival and Immediate Outcomes

Without pulmonary hypertension, survival rates are significantly higher than the 47% two-year mortality seen when PH is present. 1 For infants at 24-27 weeks gestation:

• Survival to discharge ranges from 41% at 24 weeks to 67-76% at 25-27 weeks gestation 1
• The absence of pulmonary hypertension removes the single most important predictor of poor cardiovascular outcomes and sudden death 1
• Gestational age remains the strongest predictor of survival, independent of CLD severity 1

Respiratory Trajectory

Respiratory function gradually improves over childhood, though persistent abnormalities remain:

• Bronchopulmonary dysplasia affects up to 50% of survivors, but without PH, the risk of cor pulmonale and right ventricular dysfunction is eliminated 1
• 50-57% require ongoing respiratory medications at ages 2-5 years 1
• By ages 6-15 years, FEV1 averages approximately 80% of control subjects, with obstructive patterns (low FEV1/VC ratio) and elevated RV/TLC ratios averaging 130% of controls 2
• 40-50% demonstrate airway hyperreactivity to histamine, methacholine, or exercise in childhood 2
• Gradual improvement occurs over time, though airway obstruction and hyperreactivity can persist into early adult life 2, 3

Neurodevelopmental Outcomes

The prognosis for neurodevelopment is considerably better without pulmonary hypertension:

• 69% of survivors demonstrate normal neurodevelopment on standardized testing at ages 2-5 years 1
• At 24 months, neurodevelopmental deficits range from 14-80%, but motor and cognitive function scores are consistently higher than in infants with both CLD and PH 2, 1
• Central nervous system injury—not duration of mechanical ventilation or oxygen therapy—is the primary predictor of long-term developmental outcomes 4
• Most children without major CNS complications catch up to term peers in gross motor milestones by 24-36 months corrected age 4
• Subtle deficits in fine motor skills, visual-motor integration, and cognitive function may persist into school age, with full-scale IQ scores approximately 10 points lower than term controls at 8 years 4

Cardiovascular Considerations

Without pulmonary hypertension, cardiovascular complications are reduced but not eliminated:

• Systemic hypertension still occurs in 43% of infants with CLD, typically diagnosed at mean age 4.8 months (range 2 weeks to 1 year) 2, 1
• Blood pressure monitoring is essential during inpatient and outpatient follow-up, with upper limits of normal (95th percentile) being 113 mmHg awake and 106 mmHg during sleep between 6 weeks and 1 year of age 2
• The absence of PH eliminates the risk of cor pulmonale, right ventricular dysfunction, and impaired cardiac output that dramatically worsen prognosis 1

Critical Prognostic Factors

Disease severity correlates with specific measurable parameters:

• Duration of mechanical ventilation and time without supplemental oxygen predict long-term outcomes 1
• Peripheral chemoreceptor function recovery occurs in most infants by 13 weeks postnatal age (range 9-16 weeks), except in the most severely affected who may take 6-8 months 2
• Infants who lack peripheral chemoreceptor responses at the age of peak SIDS occurrence are at higher risk for ALTE and SIDS 2

Long-Term Pulmonary Function

Exercise capacity and gas exchange show specific patterns:

• Maximal workloads and VO2max are normal or slightly reduced 2
• Limited ventilatory reserve is suggested by low VEmax and high ratio of VEmax to maximal voluntary ventilation 2
• Oxyhemoglobin desaturation during exercise may occur, related to reduced gas transfer secondary to reduced alveolar surface area 2

Clinical Monitoring Recommendations

Structured follow-up is essential:

• Pulmonary function testing during infancy aids in assessing severity, response to bronchodilators and diuretics, and longitudinal improvement 2
• Screening echocardiography should occur routinely to detect late-developing PH, as clinical signs are subtle and overlap with respiratory symptoms 1, 5
• Blood pressure monitoring should continue through the first year of life 2
• Extended developmental surveillance is required for infants with CNS injury (IVH, PVL), genetic syndromes, or significant neonatal complications 4