Fetal growth restriction is associated with an altered cardiopulmonary and cerebral hemodynamic response to surfactant therapy in preterm lambs

Background: Efficacy of surfactant therapy in fetal growth restricted (FGR) preterm neonates is unknown. Methods: Twin-bearing ewes underwent surgery at 105 days gestation to induce FGR in one twin by single umbilical artery ligation. At 123–127 days, catheters and flow probes were implanted in pulmonary and carotid arteries to measure flow and pressure. Lambs were delivered, intubated and mechanically ventilated. At 10 min, surfactant (100 mg kg ⁻¹ ) was administered. Ventilation, oxygenation, and hemodynamic responses were recorded for 1 h before euthanasia at 120 min. Lung tissue and bronchoalveolar lavage fluid was collected for analysis of surfactant protein mRNA and phosphatidylcholines (PCs). Results: FGR preterm lambs were 26% lighter than appropriate for gestational age (AGA) lambs and had baseline differences in lung mechanics and pulmonary blood flows. Surfactant therapy reduced ventilator and oxygen requirements and improved lung mechanics in both groups, although a more rapid improvement in compliance and tidal volume was observed in AGA lambs. Surfactant administration was associated with decreased mean pulmonary and carotid blood flow in FGR but not AGA lambs. No major differences in surfactant protein mRNA or PC levels were noted. Conclusions: Surfactant therapy was associated with an altered pulmonary and cerebral hemodynamic response in preterm FGR lambs.