Neonatal Respiratory Distress Syndrome Surfactant

A 28-week preterm male infant born to a mother with gestational diabetes presents with tachypnea (>60/min), nasal flaring, expiratory grunting, and intercostal retractions within 2 hours of birth. Chest X-ray shows diffuse reticulogranular opacities with air bronchograms. The infant is intubated and mechanically ventilated. The pressure-volume loop marked **B** in the diagram represents the pulmonary mechanics recorded 30 minutes after exogenous surfactant replacement via endotracheal instillation. Which of the following best explains the dramatic improvement in compliance and increased tidal volume seen in loop **B** compared to the pre-surfactant loop **A**?