COMPARISON OF 8 DIFFERENT SURFACTANT PREPARATIONS ON IMPROVEMENT OF BLOOD-GASES IN LUNG-LAVAGED RATS

A variety of surfactant preparations has been evaluated in different c linical studies but these differ too widely in their study design to a llow conclusions about differences of efficacy. Therefore, we compared six natural (Alveofact(R), BLES, Curosurf(R), Infasurf(R), Surfacten( R), and Survanta(TM)) and two synthetic (Alec(TM) and Exosurf(R)) surf actant preparations in vivo under standardized conditions. Adult rats were anaesthetized, tracheotomized, paralysed and mechanically ventila ted. Surfactant deficiency was induced by repeated whole-lung lavage. Ten min later, the animals were randomly divided and received one mi o f a surfactant suspension or served as controls. For each surfactant p reparation, three different surfactant doses (25, 50 and 100 mg/kg) we re tested. After surfactant administration, ventilator settings were n ot changed for 2 h and blood gases were measured. After 2 h, positive end-expiratory pressure (PEEP) and in parallel peak inspiratory pressu re (PIP) were twice reduced by steps of 2 cm H2O (to PIP/PEEP: 24/4 an d 22/2 cm H2O, respectively) and the effect on blood gases was studied . In the control group, arterial oxygenation did not improve and all a nimals died within the observation period due to hypoxemia, whereas th e induced acute respiratory failure reversed rapidly after all exogeno us surfactants. The effect of exogenous surfactant on arterial oxygena tion was, in general, dose-dependent. The natural surfactants were mor e effective in increasing arterial oxygenation to prelavage values tha n the synthetic surfactants. However, the natural surfactants differed in efficacy to maintain arterial oxygenation at prelavage values, esp ecially when PEEP was reduced.