What are the clinical signs of pulmonary hypertension in an infant?

Clinical Signs of Pulmonary Hypertension in Infants

Clinical signs of pulmonary hypertension in infants are often subtle and overlap with respiratory symptoms, requiring high clinical suspicion, but key manifestations include labile or profound hypoxemia despite oxygen therapy, differential oxygen saturation between upper and lower extremities, cyanosis, tachypnea, recurrent cyanotic episodes, feeding dysfunction with poor growth, and signs of right heart failure. 1, 2

Respiratory and Oxygenation Signs

• Profound hypoxemia that persists despite supplemental oxygen and mechanical ventilation is a hallmark presentation 1
• Labile oxygenation with unpredictable fluctuations in oxygen saturation, particularly triggered by handling or agitation 1
• Differential saturation (higher SpO2 in the right upper extremity compared to lower extremities) indicates right-to-left shunting through the patent ductus arteriosus 1
• Cyanosis that may be persistent or intermittent, often disproportionate to the degree of underlying lung disease 1
• Tachypnea as a compensatory mechanism for impaired gas exchange 1, 3
• Recurrent cyanotic episodes or desaturations, especially during feeding or sleep 1

Cardiovascular Signs

• Cardiomegaly on chest radiograph, reflecting right ventricular enlargement from chronic pressure overload 2
• Systolic murmurs associated with atrioventricular valve insufficiency (tricuspid regurgitation) 3
• Signs of right heart failure including hepatomegaly from venous congestion 4
• Poor cardiac output manifesting as decreased perfusion, cool extremities, or systemic hypotension 1

Growth and Feeding Difficulties

• Feeding dysfunction with poor oral intake, often requiring prolonged feeding times or gavage supplementation 1
• Poor growth and failure to thrive despite adequate caloric intake 1
• These signs reflect the increased metabolic demands and decreased oxygen delivery associated with elevated pulmonary vascular resistance 1

Respiratory Support Requirements

• Persistent or progressively increased need for high levels of respiratory support beyond what would be expected for the degree of lung disease 1
• Inability to wean consistently from supplemental oxygen at corrected age 36 weeks in premature infants with bronchopulmonary dysplasia 1
• Oxygen requirements disproportionate to radiographic lung disease severity 1
• Recurrent hospitalizations for respiratory decompensation 1

Subtle or Overlapping Signs

The American Heart Association and American Thoracic Society emphasize that clinical signs and symptoms of pulmonary hypertension can be subtle or overlap with respiratory signs, making diagnosis challenging 1, 2. This is particularly problematic in:

• Premature infants with bronchopulmonary dysplasia where respiratory and cardiac symptoms intertwine 1
• Infants with underlying lung disease where hypoxemia may be attributed solely to parenchymal disease 1

Additional Clinical Markers

• Elevated PaCO2 (hypercapnia) reflects disease severity and indicates significant airway obstruction, abnormal lung compliance, or reduced vascular surface area 1
• Apnea episodes, particularly in neonates with persistent pulmonary hypertension of the newborn 3
• Acidemia (metabolic or respiratory) from poor tissue perfusion and ventilation-perfusion mismatch 1, 3

Critical Diagnostic Caveat

Echocardiography is required to confirm the diagnosis and exclude congenital heart disease, as clinical signs alone cannot distinguish pulmonary hypertension from structural cardiac lesions 1, 2. The diagnosis should not rely solely on physical examination findings, as they lack sufficient sensitivity and specificity 1.

High-Risk Populations Requiring Screening

Even in the absence of overt clinical signs, certain populations warrant proactive screening for pulmonary hypertension:

• Preterm infants <26 weeks gestation with severe respiratory distress syndrome requiring high ventilator support 1
• Infants with oligohydramnios and intrauterine growth restriction 1
• Infants at 36 weeks corrected age with moderate-to-severe bronchopulmonary dysplasia still requiring positive-pressure ventilation 1
• Infants with congenital diaphragmatic hernia 1