ALTERATION OF PHYSICAL, AND TRANSPORT PROPERTIES OF MECONIUM BY EXOSURF®† 1364

Meconium Aspiration Syndrome (MAS) is a serious disorder in the newborn which results from both alveolar and terminal airway disease. One of the reasons for symptoms in MAS could be related to poor clearance of the meconium(MEC) from the airway. We recently demonstrated that MEC has high surface tension, poor mucociliary transportability, and high tenacity. These properties are preserved even when MEC is diluted and/or reconstituted (Peds Res, in press). The objective of this study was to measure the physical and transport properties of MEC after the addition of the artificial surfactant Exosurf®. We hypothesized that surfactant would alter the physical properties of MEC and thus allow it to be more easily mobilized. Exosurf was added to a 44 gm% MEC mixture in concentrations of 1:3, 1:1, and 3:1 (v/v), and compared to the undiluted 44 gm% MEC. Linear displacement was measured using an artificial airway model and the SensorMedics oscillator (3100) at different amplitudes (range 10-60) and inspiratory times (30% and 70%). Linear displacement of the various surfactant-MEC mixtures all increased with amplitude (p<0.0001). Importantly, linear displacement was found to directly correlate as a function of surfactant content (p<0.0001). Moreover, surfactant decreased the wettability (contact angle θ) of the surfactant-MEC preparations in a dose dependent fashion, consistent with a decrease in surface tension and improvement in transport properties. We conclude that Exosurf alters the physical properties of MEC as demonstrated by improved linear displacement and decreased wettability. These properties may be desirable when designing treatment strategies to promote the clearance of MEC from the airway.