Pulmonary Hypoplasia

Key Features

• Defined as incomplete development of one or both lungs

• Characterized by a reduction in alveolar number and a reduction in airway branches

• Present in up to 10–15% of perinatal autopsies

• Congenital diaphragmatic hernia is the most common cause, with an incidence of 1:2200 births

• Can be a result of

  • An intrathoracic mass, resulting in lack of space for the lungs to grow

  • Decreased size of the thorax

  • Decreased fetal breathing movements

  • Decreased blood flow to the lungs

  • Primary mesodermal defect affecting multiple organ systems

• Other causes include

  • Extralobar sequestration

  • Diaphragmatic eventration or hypoplasia

  • Thoracic neuroblastoma

  • Fetal hydrops

  • Fetal hydrochylothorax

• Chest cage abnormalities, diaphragmatic elevation, oligohydramnios, chromosomal abnormalities, severe musculoskeletal disorders, and cardiac lesions may also result in hypoplastic lungs

Clinical Findings

• Clinical presentation is highly variable and related to the severity of hypoplasia as well as associated abnormalities

• Often associated with pneumothorax in newborns

• Presenting symptoms in some newborns with primary hypoplasia (without associated anomalies)

  • Perinatal stress

  • Severe acute respiratory distress

  • Persistent pulmonary hypertension

• In lesser degrees of hypoplasia, presenting symptoms may be

  • Chronic cough

  • Tachypnea

  • Wheezing

  • Recurrent pneumonia

Diagnosis

• Chest radiography

  • Findings include variable degrees of volume loss in a small hemithorax with mediastinal shift

  • Pulmonary agenesis should be suspected if tracheal deviation is evident

• Chest CT scan is the optimal diagnostic method if the chest radiograph is not definitive

• Ventilation-perfusion scans, angiography, and bronchoscopy may demonstrate decreased pulmonary vascularity or premature blunting of airways associated with the maldeveloped lung tissue

• Arterial blood gas analysis determines degree of respiratory impairment

Treatment

• Supportive