Effects of surfactant supplement and end-expiratory pressure in lung-lavaged rabbits

By using adult rabbits in which the lung surfactant had been reduced by repeated whole-lung lavage, we examined the effects of surfactant supplement and positive end-expiratory pressure (PEEP). The rabbits were anesthetized with pentobarbital sodium and mechanically ventilated with pure O2. Surfactant that was extracted from pigs' lungs was supplemented to the rabbits through the trachea. The PEEP was set at 4 cmH2O. The seven rabbits that were ventilated without the supplement and without the PEEP all died of hypoxia, hypercapnia, and reduction of lung compliance within 2 h. The 18 rabbits that were ventilated with either the supplement or the PEEP showed some elevations of arterial O2 tension, but 9 of them died within 4 h. After application of both the surfactant supplement and the PEEP, six out of the eight rabbits survived for more than 11 h with nearly normal values of blood gases and compliance. We concluded that the combination of the transtracheal surfactant supplement and ventilation with PEEP has favorable therapeutic effects on surfactant deficiency.