Background Minimally Invasive Surfactant Therapy or Less Invasive Surfactant Administration (LISA) is the preferred way of administration of surfactant in neonates. Surfactant reflux resulting in ineffective surfactant delivery is considered a limiting factor in administering a higher volume surfactant like bovine surfactant by MIST.

Objectives To analyze if syringe air flush technique as incorporated in our MIST procedure protocol eliminates surfactant reflux with higher dose volume bovine surfactant in our cohort of babies that received surfactant by MIST.

Methods Syringe air flush after the surfactant administration is incorporated in our MIST procedure protocol, the default standard of administering surfactant in our neonatal units. Both porcine surfactant (1.5 ml/kg) and bovine surfactant (survanta 4–8 ml/kg) are used in our babies. We performed a subgroup analysis comparing the MIST success rate and the relevant clinical outcomes in our prospective observational cohort of MIST babies (14 times in 13 babies) that received porcine surfactant (n= 9, one time each in nine babies) versus those that received bovine surfactant (n= 5, one time each in three babies and two times in 1 baby).

Results Nine babies (gestation 27 - 36 weeks and birth weight 0.95 kg to 2.4 kg) received Curosurf (1.5 ml/kg, 200 mg/kg) by MIST one time in each baby. The median age of administration of Curosurf was 12.5h. Conduits used for MIST were by infant feeding tube in eight babies and LISA (Less Invasive Surfactant Administration) catheter in one baby. Four babies (gestation 27 – 34 weeks and birth weight 1.04 kg to 2.81 kg) received Survanta ( 4- 8 ml/kg, 100 – 200 mg/kg) five times by MIST one time each in three babies and two times in one baby. The median age of administration of survanta was 13h. The conduits used for the MIST were infant feeding tube s on two occasions, LISA catheter once and 2.0 mm Endotracheal Tube with surfactant filled syringe directly attached to the syringe hub on two occasions in one baby. Syringe air flush and checking for surfactant reflux was done as per MIST procedure protocol on all occasions after the instillation of surfactant. Success rate of MIST procedure was 100% irrespective of surfactant preparation. Equally beneficial clinical outcomes are seen in babies receiving bovine surfactant MIST and porcine surfactant MIST.

Conclusions Surfactant reflux is nullified with the incorporation of syringe air flush technique in MIST thereby ensuring equally better clinical outcomes with higher volume bovine surfactant versus porcine surfactant in this cohort. A higher dose volume surfactant can be effectively delivered by MIST.