Supraglottic Atomization of Surfactant in Spontaneously Breathing Lambs Receiving Continuous Positive Airway Pressure

Objectives: To determine the short-Term tolerance, efficacy, and lung deposition of supraglottic atomized surfactant in spontaneously breathing lambs receiving continuous positive airway pressure. Design: Prospective, randomized animal study. Setting: Animal research laboratory. Subjects: Twenty-Two preterm lambs on continuous positive airway pressure (132 ± 1 d gestational age). Interventions: Animals receiving continuous positive airway pressure via binasal prongs at 8 cm H₂O were randomized to receive atomized surfactant at approximately 60-minute of life (atom; n = 15) or not (control; n = 7). The atom group received 200 mg/kg of poractant alfa (Curosurf; Chiesi Farmaceutici SpA, Parma, Italy) over 45 minutes via a novel atomizer located in the upper pharynx that synchronized surfactant delivery with the inspiratory phase. Measurements and Main Results: Arterial blood gas, regional distribution of tidal ventilation (electrical impedance tomography), and carotid blood flow were recorded every 15 minutes until 90 minutes after stabilizing on continuous positive airway pressure. Gas exchange, respiratory rate, and hemodynamic variables, including carotid blood flow, remained stable during surfactant treatment. There was a significant improvement in arterial alveolar ratio after surfactant delivery in the atom group (p < 0.05; Sidak posttests), while there was no difference in Paco₂. Electrical impedance tomography data showed a more uniform pattern of ventilation in the atom group. In the atom group, the median (interquartile range) deposition of surfactant in the lung was 32% (22-43%) of the delivered dose, with an even distribution between the right and the left lungs. Conclusions: In our model of spontaneously breathing lambs receiving CPAP, supraglottic atomization of Curosurf via a novel device was safe, improved oxygenation and ventilation homogeneity compared with CPAP only, and provided a relatively large lung deposition suggesting clinical utility.