Time-dependency of improvements in arterial oxygenation during partial liquid ventilation in experimental acute respiratory distress syndrome

BACKGROUND: The mechanisms by which partial liquid ventilation (PLV) can improve gas exchange in acute lung injury are still unclear. Therefore, we examined the time- and dose-dependency of the improvements in arterial oxygen tension (PaO(2)) due to PLV in eight pigs with experimental lung injury, in order to discriminate increases due to oxygen dissolved in perfluorocarbon before its intrapulmonary instillation from a persistent diffusion of the respiratory gas through the liquid column. RESULTS: Application of four sequential doses of perfluorocarbon resulted in a dose-dependent increase in PaO(2). Comparison of measurements 5 and 30 min after instillation of each dose revealed a time-dependent decrease in PaO(2) for doses that approximated the functional residual capacity of the animals. CONCLUSION: Although oxygen dissolved in perfluorocarbon at the onset of PLV can cause a short-term improvement in arterial oxygenation, diffusion of oxygen through the liquid may not be sufficient to maintain the initially observed increase in PaO(2).