Surfactant Delivery Is Crucial for Enhancing Function of Ex-Vivo Premature Sheep Lungs: A Feasibility Study.

Aim: To compare effects of bolus and aerosolization surfactant delivery methods and ventilatory support on improving ex-vivo premature sheep lung function.

Methods: The xPULM lung simulator was used with 16 ex-vivo preterm sheep lungs, of which 6 were analyzed in the bolus group and 3 in the aerosol group after excluding 7 lungs that ruptured during the trial. Surfactant (0.5 mL poractant alfa) was administered via bolus injection or aerosolization. Tidal volume (VT) was measured before and after administration at positive end-expiratory pressure (PEEP) levels of 0, 5, 10, and 15 cmH₂O.

Results: Surfactant administration significantly increased VT (presurfactant median VT = 0.21 mL; post-surfactant median VT = 1.03 mL, p < 0.001). There was a trend toward higher median VT with bolus delivery (1.48 mL) compared to aerosolized delivery (0.43 mL) with borderline significance (p = 0.047) between the two delivery methods. High PEEP levels before surfactant delivery caused lung overdistention. Histological analysis revealed minimal lung tissue injury across samples, despite experimental challenges.

Conclusions: In ex-vivo preterm sheep lungs, surfactant delivery is the primary driver of improved lung function, while PEEP has a smaller impact. The xPULM lung simulator enables research during spontaneous breathing while avoiding ethical issues associated with animal models.