EFFECTS OF SURFACTANT DISTRIBUTION AND VENTILATION STRATEGIES ON EFFICACY OF EXOGENOUS SURFACTANT

The effects of both surfactant distribution patterns and ventilation s trategies utilized after surfactant administration were assessed in lu ng-injured adult rabbits. Animals received 50 mg/kg surfactant via int ratracheal instillation in volumes of either 4 or 2 ml/kg. A subset of animals from each treatment group was euthanized for evaluation of th e exogenous surfactant distribution. The remaining animals were random ized into one of three ventilatory groups: group 1 [tidal volume (VT) of 10 ml/kg with 5 cmH(2)O positive end-expiratory pressure (PEEP)]; g roup 2 (VT of 5 ml/kg with 5 cmH(2)O PEEP); or group 3 (VT of 5 ml/kg with 9 cmH(2)O PEEP). Animals were ventilated and monitored for 3 h. D istribution of the surfactant was more uniform when it was delivered i n the 4 ml/kg volume, When the distribution of surfactant was less uni form, arterial Po-2 values were greater in groups 2 and 3 compared wit h group 1. Oxygenation differences among the different ventilation str ategies were less marked in animals with the more uniform distribution pattern of surfactant (4 ml/kg). In both surfactant treatment groups, a high mortality was observed with the ventilation strategy used for group 3. We conclude that the distribution of exogenous surfactant aff ects the response to different ventilatory strategies in this model of acute lung injury.