A rising-FiO2 preterm on CPAP — OSCE

Candidate brief

You are the neonatal registrar called to review a 27-week gestation infant two hours after birth. The infant was born to a mother who received a full course of antenatal corticosteroids. The birth weight is 920 grams, the temperature is 36.8 degrees, and the infant is on nasal CPAP at 6 cm of water. The inspired oxygen has risen over the last hour from 0.25 to 0.38, with grunting, marked subcostal retractions and nasal flaring. The pre-ductal saturation is 92 percent at the current FiO2. A chest radiograph shows low lung volumes with fine granular opacities and air bronchograms. [1]

Task

1. State the diagnosis and the pathophysiological mechanism. [1]
2. Give the indication for surfactant, the preparation and dose, and the preferred technique. [1] [2]
3. State the oxygen saturation target and the evidence base, and the caffeine dose and its rationale. [5] [8]
4. Outline the prevention of bronchopulmonary dysplasia and the planned follow-up. [1]

Examiner discussion points

• Why does the FiO2 climbing past 0.30 on CPAP trigger surfactant rather than continued observation? The trend signals the surfactant reserve is exhausted and the disease is worsening. [1]
• How does the LISA technique differ from intubation with surfactant, and what is its advantage? It delivers surfactant via a thin catheter while the infant stays on CPAP, reducing mechanical ventilation and bronchopulmonary dysplasia. [1] [2]
• Why target 91 to 95 percent rather than lower or higher? NeOProM showed the higher target reduced mortality, while the lower target reduced retinopathy but increased death. [5]
• What must you do to the ventilator within minutes of giving surfactant? Wean it — compliance improves rapidly and over-distension risks volutrauma and air leak. [1]

Key teaching points

The case turns the surfactant-deficiency mechanism into a sequence of decisions: recognise the rising FiO2 as the surfactant reserve failing, meet the FiO2-over-0.30 threshold with surfactant by the least invasive route, set the oxygen target by the NeOProM evidence, add caffeine to protect the drive and aid extubation, and build the prevention of bronchopulmonary dysplasia into every step. [1] [5]