ObjectiveTo compare the efficacy of single, multiple, and continuous application of perfluorocarbon (PFC) FC-77 on gas exchange and lung pathology in a prolonged 24-hr study.DesignControlled animal trial.SettingResearch laboratory in a university setting.SubjectsTwenty-one newborn piglets (mean weight 1.94 kg).InterventionsAfter intubation and instrumentation, the anesthetized animals were randomized in three groups: a) animals receiving one 1-hr session of partial liquid ventilation (PLV) followed by 23 hrs of conventional ventilation (CV), designated as the single PLV (S-PLV) group; b) animals receiving multiple 1-hr sessions of PLV with intermittent CV, designated as the multiple PLV (M-PLV) group; and c) animals receiving continuous PLV over 24 hrs, designated as the continuous PLV (C-PLV) group. After lung injury was induced with repeated saline lavage, specific ventilatory treatment was initiated. The oxygenation index, Pao2/Fio2ratio, and ventilatory efficacy index were determined before and after lung injury and during the 24-hr course. After 24 hrs, the lungs were removed for histopathologic examination.Measurements and Main ResultsGas exchange variables improved within 60 mins in all groups after the initiation of the specific ventilatory treatment (p< .01). The best outcome was observed in the C-PLV group, which provided a continuously stable gas exchange over the 24-hr period. S-PLV initially improved gas exchange, but after 6 hrs all variables were impaired when compared with C-PLV (p< .01). M-PLV transiently improved gas exchange variables after each PFC application; however, M-PLV was associated with a significant deterioration of all pulmonary variables during the 24-hr course. The lungs of the animals in the M-PLV group demonstrated an increased lung injury score (p< .01) and increased morphometric values (p< .05) when compared with C-PLV.ConclusionsIn surfactant deficient lungs, single and multiple applications of PFC only transiently improved oxygenation. Multiple PFC fillings with intermittent gas ventilation led to a deterioration of gas exchange during the 24-hr study and severe lung damage. Continuous PLV provides the best gas exchange and the most favorable histopathologic outcome.