Response to Cummings

Abstract

We would like to thank Dr Cummings for giving us the opportunity to explain our study results. Results from nine randomized, controlled, trials (RCTs),1, 2, 3, 4, 5, 6, 7, 8, 9 including the one that has been just published (e-pub ahead of print) by Dizdar et al.9 and meta-analyses10, 11, 12 comparing animal-derived surfactants, namely, poractant alfa (PA), beractant (BE), bovactant (BO) and/or calfactant (CA), have consistently shown faster weaning of oxygen and mean airway pressure, less need for redosing, fewer days on oxygen and mechanical ventilation, shorter length of stay (LOS) as well as survival advantage in babies treated with PA. These advantages with PA over BE, CA or BO are likely related to major biological and/or biochemical differences between these animal-derived surfactant preparations. PA contains the highest amount of phospholipids when compared with BE or CA. Higher amount of phospholipids has been shown to downregulate oxidative functions in monocytes and confer better anti-inflammatory properties.13 In addition, bacterial growth in different surfactant preparations is influenced by microbial species and the composition and dose of the surfactant. PA was bactericidal in a dose-dependent fashion and differed from BE and BO, a surfactant preparation similar to CA.14 PA contains the highest amount of plasmalogens (PL) when compared with BE.15 BO contains the lowest amount of PL.15 PL are anti-oxidant phospholipids and presence of higher amounts of PL in the tracheal aspirates from pre-term infants has been shown to be associated with a lower risk for bronchopulmonary dysplasia (BPD).16 Also, the amount of surfactant-associated protein B (SP-B) is highest in PA when compared with BE or CA. SP-B is the most important SP in helping the phospholipids to rapidly adsorb at the air–liquid interphase and in decreasing surface tension. Furthermore, the phospholipid molecular species of PA is much closer to that of human surfactant.17, 18