Hyaline Membrane Disease

Key Features

• Most common cause of respiratory distress in the preterm infant

• Caused by a deficiency of surfactant production as well as surfactant inactivation by protein leak into airspaces

• Incidence increases from 5% of infants born at 35–36 weeks' gestation to more than 50% of infants born at 26–28 weeks' gestation

Clinical Findings

• Infants show all the clinical signs of respiratory distress

• On auscultation, air movement is diminished despite vigorous respiratory effort

• Tachypnea, cyanosis, and expiratory grunting are seen

Diagnosis

• Chest radiograph demonstrates diffuse bilateral atelectasis, causing a ground-glass appearance

• Major airways are highlighted by the atelectatic air sacs, creating air bronchograms

• In the unintubated child, doming of the diaphragm and hypoinflation occur

Treatment

• Supplemental oxygen, nasal CPAP, early intubation for surfactant administration and ventilation, and placement of umbilical artery and vein lines are initial required interventions

• In stable infants, a trial of nasal CPAP at 5–6 cm H₂O pressure can be attempted prior to intubation and surfactant administration

• Nasal intermittent positive-pressure ventilation (NIPPV) is another modality that may be attempted for ventilatory support

• Ventilators

  • Can deliver breaths synchronized with the infant's respiratory efforts (synchronized intermittent mandatory ventilation) and accurately deliver a preset tidal volume (5–6 mL/kg) should be used

  • Alternatively, pressure limited ventilation with measurement of exhaled tidal volumes can be used

  • High-frequency ventilators are available for rescue of infants doing poorly on conventional ventilation

• Surfactant replacement

  • Dosages

    • Bovine-derived beractant (Survanta) is 4 mL/kg

    • Calf lung surfactant extract (Infasurf) is 3 mL/kg

    • Porcine-derived poractant (Curosurf) is 1.25–2.5 mL/kg, given intratracheally

    • Repeat dosing is indicated in infants who remain on the ventilator receiving more than 30–40% oxygen

    • A total of two to three doses given 8–12 hours apart may be administered

  • As the disease evolves, proteins that inhibit surfactant function leak into the air spaces, making surfactant replacement less effective.