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.