Resistance of different surfactant preparations to inactivation by meconium

A disease similar to acute respiratory distress syndrome may occur in neona tes after aspiration of meconium. The aim of the study was to compare the i nhibitory effects of human meconium on the following surfactant preparation s suspended at a concentration of 2.5 mg/mL: Curosurf, Alveofact, Survanta, Exosurf, Pumactant, rabbit natural surfactant from bronchoalveolar lavage, and two synthetic surfactants based on recombinant surfactant protein-C (V enticute) or a leucine/lysine polypeptide. Minimum surface tension, determi ned with a pulsating bubble surfactometer, was increased >10 mN/m at meconi um concentrations greater than or equal to0.04 mg/mL for Curosurf, Alveofac t, or Survanta, greater than or equal to0.32 mg/mL for recombinant surfacta nt protein-C, greater than or equal to1.25 mg/mL for leucine/lysine polypep tide, and greater than or equal to 20 mg/mL for rabbit natural surfactant. The protein-free synthetic surfactants Exosurf and Pumactant did not reach minimum surface tension <10 mN/m even in the absence of meconium. We conclu de that surfactant activity is inhibited by meconium in a dose-dependent ma nner. Recombinant surfactant protein-C and leucine/lysine polypeptide surfa ctant were more resistant to inhibition than the modified natural surfactan ts Curosurf, Alveofact, or Survanta but less resistant than natural lavage surfactant containing surfactant protein-A. We speculate that recombinant h ydrophobic surfactant proteins or synthetic analogs of these proteins can b e used for the design of new surfactant preparations that are relatively re sistant to inactivation and therefore suitable for treatment of acute respi ratory distress syndrome.