For decades, the fluid-filled lung has been a valuable research model for understanding normal and abnormal pulmonary physiology. It has lagged behind, however, as a useful therapeutic tool. Recently, the potential applications of perflubron's physicochemical and biologic properties have been realized. In animal models of several types of hypoxic respiratory failure, perflubron's efficacy in improving gas exchange and compliance has been demonstrated. Preliminary clinical studies of PLV in neonates who have RDS and CDH, and in children and adults who have ARDS have shown promise. Pivotal prospective, controlled studies have yet to be completed.