Objective: To evaluate the applicability and potential effectiveness of a technique of minimally-invasive surfactant therapy (MIST) in preterm infants on continuous positive airway pressure (CPAP).

Methods: An open feasibility study of MIST was conducted at two sites. Infants were eligible for MIST if needing CPAP pressure ≥7 cm H₂O and FiO₂ ≥0.3 (25–28 weeks gestation, n=38) or ≥0.35 (29–32 weeks, n=23). Without premedication, a narrow-bore catheter was inserted through the vocal cords under direct vision. Surfactant (100 or 200 mg/kg Curosurf ) was then instilled, followed by reinstitution of CPAP. Outcomes were compared between surfactant-treated infants and historical controls achieving the same CPAP and FiO₂ thresholds.

Results: Surfactant was successfully administered via MIST in all cases, with a rapid and sustained reduction in FiO2 thereafter. For infants at 25–28 weeks gestation, need for intubation <72 h was diminished after MIST compared with controls (32% vs 68%; OR 0.21, 95% CI 0.083 to 0.55), with a similar trend at 29–32 weeks (22% vs 45%; OR 0.34, 95% CI 0.11 to 1.1). Duration of ventilation and incidence of bronchopulmonary dysplasia were similar, but infants receiving MIST had a shorter duration of oxygen therapy.

Conclusion: Surfactant delivery via a narrow-bore tracheal catheter is feasible and potentially effective, and deserves further investigation in clinical trials.