Dextran reduces surfactant inhibition by meconium

We have previously shown that an addition of dextran to surfactant increases resistance to inactivation by albumin. The present study was designed to investigate whether dextran has a protective effect against inactivation of surfactant by meconium. The dynamic surface properties of various mixtures of modified natural surfactant (Curosurf(R)), meconium and dextran were evaluated with the pulsating bubble technique. In the absence of meconium, an addition of dextran at 10 mg ml(-1) significantly shortened the surface adsorption time of Curosurf suspended in normal saline at a concentration of 5 mg ml(-1) from 1.6 +/- 1.3 (mean +/- SD) sec to 0.4 +/- 0.4 sec (p < 0.05). Meconium at 5 mg ml(-1) increased the mean minimum surface tension (<gamma>(min)) after 3 min of pulsation from 2.1 mN m(-1) to 24 mN m(-1) (p < 0.05). An addition of dextran at 5 and 10 mg ml(-1) to the meconium-surfactant mixture significantly reduced the <gamma>(min) to 6.4 +/- 4.5 mN m(-1) and 2.6 +/- 5.6 mN m(-1), respectively (p < 0.05 vs dextran 0 mg ml(-1)). Meconium also increased the maximum surface tension (<gamma>(max)) of Curosurf from about 33 mN m(-1) to 53 mN m(-1). An addition of dextran at 5 and 10 mg ml(-1) to the meconium-surfactant mixture reduced the gamma (max) to 41 and 39 mN m(-1), respectively (p < 0.05 vs dextran 0 mg ml(-1)). There were significant negative correlations between dextran concentration and both <gamma>(min) and gamma (max). We conclude that dextran reduces surfactant inhibition by meconium in a dose-dependent manner.